Re: [RE-wrenches] Conductor Sizing for Supply Side Connection
HI Chris; Just to be clear, the cables are not going to fail just because they aren't code compliant; unless you meant they would fail an inspection. I've included a picture of my own service rated at 150 amps. Using table 310.15(B)7 (which I believe is the correct table for sizing the service conductors, not 310.B16 or 17), My side is 2/0 aluminum, but the utility side is #4 aluminum. The utility is not held to NEC requirements, but a fire isn't starting just because they're grossly undersized by NEC standards. NEC has huge safety factors, which are appropriate for wires hidden in walls that are expected to last the life of the house. Finally, to be code compliant with a supply side 60 A connection, I believe the service conductors would need to be 3/0 Cu or 250 MCM Aluminum. That would correspond to a 225 A service (x 120%) or 270 amps, leaving 5 amps to spare. As Dave mentioned, replacing the service conductors would probably not be a reasonable option. Downsizing the main breaker to 175 A, would also work (175 + 60 < 200 x 120%) and since some of the loads are being transferred to the 60A breaker, downsizing the main should be compliant. R.Ray Walters CTO, Solarray, Inc Nabcep Certified, Licensed Contractor 808 269-7491 On 3/9/2013 8:17 AM, Christopher Warfel wrote: Had a couple of minutes here, so with the load side connection, the 200 amp breaker would operate to protect all conductors. With a supply side connection, the battery charger could be pulling 60 amps, the main panel 200, and the service conductors sized for 240 amps would fail. 2/0 in free air is rated for 265A T310.15(B)(17), but would you say that T310.(B)(16) applies for service conductors and then 2/0 is 175? I am really starting to hate solar. On 2/28/2013 10:21 AM, Dave Click wrote: As a note, supply side connections have an extra complication with battery backup systems. With a regular GT inverter you're just pushing current into that interconnection point and you can work out easily that you won't have any overcurrent issues unless you made a big mistake and your inverter output exceeds the rating of your service conductors. However, with a battery system you're also potentially pulling current from that point. Before the battery inverter is installed your main breaker protects your service conductors, but if the inverter is pulling in 60A and the main breaker is also operating near its capacity, you could have >240A running over 200A service conductors with no breakers tripping. You would overwhelm the capacity of the service [230.23(A)] and no breakers would trip. You could fix this by replacing your service conductors back to the transformer (I'm just saying that it's an option) or downsizing the main breaker, and at that point you're probably better off just making it a load side connection. I'd go load side and argue with the AHJ to use the 2011 update mentioned earlier. Dave On 2013/2/28 9:55, Garrison Riegel wrote: Allen, The benefit I see would be to allow for a code compliant load side connection on a 200A panel with a 200A MB, where the AHJ is on the 2008 NEC or older and will not listen to your good logic. I don't think this would always be the best option, but if backup loads and inverter output were less than 32A then a 40A OCPD in the main panel should be fine? Since it sounds like the 60A breaker in the main panel is not a safety issue, but a design consideration, I suppose I would just prefer flexibility when possible. That said, this AHJ is on the 2008, and the loads will be less than 30A, but based on this conversation I plan to go with a 60A and try to convince the AHJ that it will be code compliant in their future! Thanks, Garrison *From:*re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *Allan Sindelar *Sent:* Thursday, February 28, 2013 8:14 AM *To:* RE-wrenches *Subject:* Re: [RE-wrenches] Conductor Sizing for Supply Side Connection Garrison, I don't know why it's not listed as 60A max, but my own internal logic would ask why it should be. The only benefit I could see for using smaller than a 60A breaker would be to allow use of #8 conductors (allowed with a 40A or 50A breaker) instead of the #6 necessary with a 60A breaker. And of course, you could use a 40A breaker with #6 conductors, so theoretically it would be fine. I just fail to see any benefit to doing so. Allan *Allan Sindelar* al...@positiveenergysolar.com <mailto:al...@positiveenergysolar.com> NABCEP Certified Photovoltaic Installer NABCEP Certified Technical Sales Professional New Mexico EE98J Journeyman Electrician Founder and Chief Technology Officer *Positive Energy, Inc.* 3209 Richards Lane (note new address) Santa Fe, New Mexico 87507 *505 424-1112* www.positiveenergysolar.com <http://www.positiveenergysolar.com/&
Re: [RE-wrenches] Conductor Sizing for Supply Side Connection
Had a couple of minutes here, so with the load side connection, the 200
amp breaker would operate to protect all conductors. With a supply side
connection, the battery charger could be pulling 60 amps, the main panel
200, and the service conductors sized for 240 amps would fail. 2/0 in
free air is rated for 265A T310.15(B)(17), but would you say that
T310.(B)(16) applies for service conductors and then 2/0 is 175?
I am really starting to hate solar.
On 2/28/2013 10:21 AM, Dave Click wrote:
As a note, supply side connections have an extra complication with
battery backup systems. With a regular GT inverter you're just pushing
current into that interconnection point and you can work out easily
that you won't have any overcurrent issues unless you made a big
mistake and your inverter output exceeds the rating of your service
conductors. However, with a battery system you're also potentially
pulling current from that point. Before the battery inverter is
installed your main breaker protects your service conductors, but if
the inverter is pulling in 60A and the main breaker is also operating
near its capacity, you could have >240A running over 200A service
conductors with no breakers tripping. You would overwhelm the capacity
of the service [230.23(A)] and no breakers would trip. You could fix
this by replacing your service conductors back to the transformer (I'm
just saying that it's an option) or downsizing the main breaker, and
at that point you're probably better off just making it a load side
connection. I'd go load side and argue with the AHJ to use the 2011
update mentioned earlier.
Dave
On 2013/2/28 9:55, Garrison Riegel wrote:
Allen,
The benefit I see would be to allow for a code compliant load side
connection on a 200A panel with a 200A MB, where the AHJ is on the
2008 NEC or older and will not listen to your good logic. I don't
think this would always be the best option, but if backup loads and
inverter output were less than 32A then a 40A OCPD in the main panel
should be fine? Since it sounds like the 60A breaker in the main
panel is not a safety issue, but a design consideration, I suppose I
would just prefer flexibility when possible.
That said, this AHJ is on the 2008, and the loads will be less than
30A, but based on this conversation I plan to go with a 60A and try
to convince the AHJ that it will be code compliant in their future!
Thanks,
Garrison
*From:*re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of
*Allan Sindelar
*Sent:* Thursday, February 28, 2013 8:14 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Conductor Sizing for Supply Side Connection
Garrison,
I don't know why it's not listed as 60A max, but my own internal
logic would ask why it should be. The only benefit I could see for
using smaller than a 60A breaker would be to allow use of #8
conductors (allowed with a 40A or 50A breaker) instead of the #6
necessary with a 60A breaker. And of course, you could use a 40A
breaker with #6 conductors, so theoretically it would be fine. I just
fail to see any benefit to doing so.
Allan
*Allan Sindelar*
al...@positiveenergysolar.com <mailto:al...@positiveenergysolar.com>
NABCEP Certified Photovoltaic Installer
NABCEP Certified Technical Sales Professional
New Mexico EE98J Journeyman Electrician
Founder and Chief Technology Officer
*Positive Energy, Inc.*
3209 Richards Lane (note new address)
Santa Fe, New Mexico 87507
*505 424-1112*
www.positiveenergysolar.com <http://www.positiveenergysolar.com/>
On 2/28/2013 6:27 AM, Garrison Riegel wrote:
Thanks Allen for clarifying why a 60A is required. I was
wondering. The spec does list a surge current of 9000W so I
thought that may be the rationale, but even that would only
require a 50A, and since this surge occurs during 'stand-alone
mode' it didn't seem to apply to the OCPD at the main panel.
Your explanation makes more sense, but I wonder why then they
don't list the AC input breaker size as 60A /max/. If you have
few backup loads, and are not on the 2011 NEC, a 40A could
theoretically be fine?
Thanks all for your thoughts, much appreciated.
Garrison
*From:*re-wrenches-boun...@lists.re-wrenches.org
<mailto:re-wrenches-boun...@lists.re-wrenches.org>
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of
*Allan Sindelar
*Sent:* Wednesday, February 27, 2013 6:08 PM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Conductor Sizing for Supply Side
Connection
August,
The 60A breaker is intended to allow grid power to pass through
to the loads in excess of the inverter's stand-alone output. The
point of 705.12 (moved in the 2011 NEC from 690.64 (B)(2)) is to
differentiate between load pass-through current and sell current.
Re: [RE-wrenches] Conductor Sizing for Supply Side Connection
William - You're correct, I was confused - thanks for setting me straight! Regards, Gary On 3/1/13 1:05 PM, William Miller wrote: Gary: I think you are a little confused about the operating modes of the XW inverter: In the AC Passthru mode, no battery charging occurs. Below is the passage from the manual that describes this: /The AC connected to the AC1 or AC2 input is passing directly through the Xantrex XW Series Inverter/Charger to the loads. The batteries are not being charged in this state. /In the normal transfer mode, battery charging does occur. It is my clear understanding that the Xantrex SW and XW inverters and the Outback FX and Radian inverters will regulate battery charging so that the charger circuit uses only excess amperage available. For example: If the input breaker size is programmed for 60 amps and there is 60 amps of load, 0 amps of AC will be used for battery charging. If the load decreases to 50 amps, 10 amps of AC will be used for battery charging, etc.. Therefore, the OCPD does _not_ need to be sized to accommodate both uses of input AC. Below is a passage from the XW Operating Manual that describes this: /In addition, the battery charger can reduce its charging current to the batteries so the combined charge AC current and total load current does not exceed the capacity of the generator or trip its output breakers or fuses. /Extending this discussion beyond the current topic (pun intended), we need to understand what happens if the connected loads exceed the input breaker rating. Here the game changes. The FX inverter can not prevent the overload from passing to the input breaker, possibly tripping it. The SW, XW and Radian inverters can provide "Generator Support." Do not confuse Generator Support with Generator Remote start functions. Generator Support allows the inverter to sync to, and assist the AC input source in powering loads. To use the example above: If the load rises to 70 amps, the inverter draws energy from the batteries to provide the last 10 amps. Below is the passage from the XW manual that describes this: /AC2 Breaker: Sets the AC2 (Gen) breaker size, based on the size of the installed AC breaker. The breaker size must not exceed the capacity of the generator. The Xantrex XW Series Inverter/Charger limits the maximum input current to this setting by derating its charging current to an equivalent of 80% of the AC breaker size. If the connected loads exceed the AC2 breaker setting, the AC breaker trips. The breaker may not trip if Gen Support is enabled and Gen Amps is configured not to exceed the generator's rated output current. /I hope this information is relevant, correct and helpful. Sincerely, William Miller At 08:24 AM 3/1/2013, you wrote: Larry: In the case of the Xantrex XW Series, while in the "AC Pass-Thru" Mode, the internal transfer switch relay connects the protected loads directly to the AC1 grid input. The XW internal battery charger is then activated to recharge the battery bank. The OCPD(s) through which the protected load amps and charging amps are passing must be sized to accommodate both at the same time. Regards, Gary Willett Icarus Solar ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Change email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Change email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
Re: [RE-wrenches] Conductor Sizing for Supply Side Connection
Gary: I think you are a little confused about the operating modes of the XW inverter: In the AC Passthru mode, no battery charging occurs. Below is the passage from the manual that describes this: The AC connected to the AC1 or AC2 input is passing directly through the Xantrex XW Series Inverter/Charger to the loads. The batteries are not being charged in this state. In the normal transfer mode, battery charging does occur. It is my clear understanding that the Xantrex SW and XW inverters and the Outback FX and Radian inverters will regulate battery charging so that the charger circuit uses only excess amperage available. For example: If the input breaker size is programmed for 60 amps and there is 60 amps of load, 0 amps of AC will be used for battery charging. If the load decreases to 50 amps, 10 amps of AC will be used for battery charging, etc.. Therefore, the OCPD does not need to be sized to accommodate both uses of input AC. Below is a passage from the XW Operating Manual that describes this: In addition, the battery charger can reduce its charging current to the batteries so the combined charge AC current and total load current does not exceed the capacity of the generator or trip its output breakers or fuses. Extending this discussion beyond the current topic (pun intended), we need to understand what happens if the connected loads exceed the input breaker rating. Here the game changes. The FX inverter can not prevent the overload from passing to the input breaker, possibly tripping it. The SW, XW and Radian inverters can provide "Generator Support." Do not confuse Generator Support with Generator Remote start functions. Generator Support allows the inverter to sync to, and assist the AC input source in powering loads. To use the example above: If the load rises to 70 amps, the inverter draws energy from the batteries to provide the last 10 amps. Below is the passage from the XW manual that describes this: AC2 Breaker: Sets the AC2 (Gen) breaker size, based on the size of the installed AC breaker. The breaker size must not exceed the capacity of the generator. The Xantrex XW Series Inverter/Charger limits the maximum input current to this setting by derating its charging current to an equivalent of 80% of the AC breaker size. If the connected loads exceed the AC2 breaker setting, the AC breaker trips. The breaker may not trip if Gen Support is enabled and Gen Amps is configured not to exceed the generator's rated output current. I hope this information is relevant, correct and helpful. Sincerely, William Miller At 08:24 AM 3/1/2013, you wrote: Larry: In the case of the Xantrex XW Series, while in the "AC Pass-Thru" Mode, the internal transfer switch relay connects the protected loads directly to the AC1 grid input. The XW internal battery charger is then activated to recharge the battery bank. The OCPD(s) through which the protected load amps and charging amps are passing must be sized to accommodate both at the same time. Regards, Gary Willett Icarus Solar ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Change email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
Re: [RE-wrenches] Conductor Sizing for Supply Side Connection
Garrison and Ross,
Although there are times that the buss bar
rating may be higher than the main breaker
rating, the difficulty is in
obtaining documentation to verify that.
Sometimes it states the rating clearly on the panel label but that seems to be
the exception, not the rule.
Roy Butler
NABCEP Certified Small Wind Installer®
NABCEP Certified Solar PV Installer®
NYSERDA eligible PV & wind installer
Four Winds Renewable Energy, LLC
8902 Route 46, Arkport, NY 14807
607-324-9747 www.four-winds-energy.com
Join us at the 9th Annual Small Wind Conference
A Gathering of Installers, Manufacturers, Dealers, & Distributors
June 18 and 19, 2013 in Stevens Point, Wisconsin
www.smallwindconference.com
Although no trees were killed in the sending of this message,
a large number of electrons were terribly inconvenienced.
On 3/1/2013 11:54 AM, Garrison Reigel wrote:
Good point Ross. The panel is marked
as a 200A with no indication that the bus has a higher rating,
so I've assumed 200A. I considered downsizing the MB, but it's
an discontinued panel, and filled to capacity so not exactly
ideal.
Thanks,
Garrison
From:
re-wrenches-boun...@lists.re-wrenches.org
[re-wrenches-boun...@lists.re-wrenches.org] on behalf of
Ross Taylor [wind.trai...@gmail.com]
Sent: Thursday, February 28, 2013 9:24 PM
To: re-wrenches@lists.re-wrenches.org
Subject: Re: [RE-wrenches] Conductor Sizing for
Supply Side Connection
Hi Garrison,
This is a great discussion and I think I've read all
the responses. If I missed this question, please forgive
me. But, in your original post you refer to a 200 amp
service. I don't, though, see mention of the rating of
the bus bars. The bus bars may be rated for something
more than 200 amps, depending upon the panel, even if
they're protected by a 200 amp main disconnect. If so,
that would increase your backfeed breaker sizing options.
Best wishes,
Ross Taylor
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Re: [RE-wrenches] Conductor Sizing for Supply Side Connection
Good point Ross. The panel is marked as a 200A with no indication that the bus has a higher rating, so I've assumed 200A. I considered downsizing the MB, but it's an discontinued panel, and filled to capacity so not exactly ideal. Thanks, Garrison From: re-wrenches-boun...@lists.re-wrenches.org [re-wrenches-boun...@lists.re-wrenches.org] on behalf of Ross Taylor [wind.trai...@gmail.com] Sent: Thursday, February 28, 2013 9:24 PM To: re-wrenches@lists.re-wrenches.org Subject: Re: [RE-wrenches] Conductor Sizing for Supply Side Connection Hi Garrison, This is a great discussion and I think I've read all the responses. If I missed this question, please forgive me. But, in your original post you refer to a 200 amp service. I don't, though, see mention of the rating of the bus bars. The bus bars may be rated for something more than 200 amps, depending upon the panel, even if they're protected by a 200 amp main disconnect. If so, that would increase your backfeed breaker sizing options. Best wishes, Ross Taylor ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Change email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
Re: [RE-wrenches] Conductor Sizing for Supply Side Connection
Larry:
In the case of the Xantrex XW Series, while in the "AC Pass-Thru" Mode,
the internal transfer switch relay connects the protected loads directly
to the AC1 grid input. The XW internal battery charger is then activated
to recharge the battery bank.
The OCPD(s) through which the protected load amps and charging amps are
passing must be sized to accommodate both at the same time.
Regards,
Gary Willett
Icarus Solar
On 3/1/13 8:40 AM, wire...@gmail.com wrote:
Gary,
I thought most inverters share power. So if the inverter has a 60A
transfer switch and all of that is needed for loads then none for
charging and as load demand decreases, charging increases.
Larry Liesner
Elektron Solar
On Feb 28, 2013 11:33 AM, <mailto:g...@icarussolarservices.com>> wrote:
Garrison, et al:
Another consideration when sizing the POCC OCPD (either load side
or supply side) is charging current when the grid power returns
and the battery bank is near the LBCO voltage.
Bulk charging current and AC pass-through current both must be
considered when sizing the POCC OCPD.
Regards,
Gary Willett
Icarus Solar
On Thu, 28 Feb 2013 10:04:51 -0600, Garrison Riegel
mailto:garri...@solarserviceinc.com>> wrote:
Great point Dave. It crossed my mind that it was technically
possible, but figured since I would be removing loads off the
main panel it was highly unlikely. Thanks for the code
reference. I'll go load side, and be prepared for some
discussion.
Thanks,
Garrison
*From:*re-wrenches-boun...@lists.re-wrenches.org
<mailto:re-wrenches-boun...@lists.re-wrenches.org>
[mailto:re-wrenches-boun...@lists.re-wrenches.org
<mailto:re-wrenches-boun...@lists.re-wrenches.org>] *On Behalf
Of *Dave Click
*Sent:* Thursday, February 28, 2013 9:21 AM
*To:* re-wrenches@lists.re-wrenches.org
<mailto:re-wrenches@lists.re-wrenches.org>
*Subject:* Re: [RE-wrenches] Conductor Sizing for Supply Side
Connection
As a note, supply side connections have an extra complication
with battery backup systems. With a regular GT inverter you're
just pushing current into that interconnection point and you
can work out easily that you won't have any overcurrent issues
unless you made a big mistake and your inverter output exceeds
the rating of your service conductors. However, with a battery
system you're also potentially pulling current from that
point. Before the battery inverter is installed your main
breaker protects your service conductors, but if the inverter
is pulling in 60A and the main breaker is also operating near
its capacity, you could have >240A running over 200A service
conductors with no breakers tripping. You would overwhelm the
capacity of the service [230.23(A)] and no breakers would
trip. You could fix this by replacing your service conductors
back to the transformer (I'm just saying that it's an option)
or downsizing the main breaker, and at that point you're
probably better off just making it a load side connection. I'd
go load side and argue with the AHJ to use the 2011 update
mentioned earlier.
Dave
On 2013/2/28 9:55, Garrison Riegel wrote:
Allen,
The benefit I see would be to allow for a code compliant
load side connection on a 200A panel with a 200A MB, where
the AHJ is on the 2008 NEC or older and will not listen to
your good logic. I don't think this would always be the
best option, but if backup loads and inverter output were
less than 32A then a 40A OCPD in the main panel should be
fine? Since it sounds like the 60A breaker in the main
panel is not a safety issue, but a design consideration, I
suppose I would just prefer flexibility when possible.
That said, this AHJ is on the 2008, and the loads will be
less than 30A, but based on this conversation I plan to go
with a 60A and try to convince the AHJ that it will be
code compliant in their future!
Thanks,
Garrison
*From:*re-wrenches-boun...@lists.re-wrenches.org
<mailto:re-wrenches-boun...@lists.re-wrenches.org>
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On
Behalf Of *Allan Sindelar
*Sent:* Thursday, February 28, 2013 8:14 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Conductor Sizing for Supply
Side Connection
Garrison,
I don't know why it's not listed as 60A max, but my own
Re: [RE-wrenches] Conductor Sizing for Supply Side Connection
Gary, I thought most inverters share power. So if the inverter has a 60A transfer switch and all of that is needed for loads then none for charging and as load demand decreases, charging increases. Larry Liesner Elektron Solar On Feb 28, 2013 11:33 AM, wrote: > Garrison, et al: > > > > Another consideration when sizing the POCC OCPD (either load side or > supply side) is charging current when the grid power returns and the > battery bank is near the LBCO voltage. > > > > Bulk charging current and AC pass-through current both must be considered > when sizing the POCC OCPD. > > > > Regards, > > > > Gary Willett > > Icarus Solar > > On Thu, 28 Feb 2013 10:04:51 -0600, Garrison Riegel < > garri...@solarserviceinc.com> wrote: > > Great point Dave. It crossed my mind that it was technically possible, > but figured since I would be removing loads off the main panel it was > highly unlikely. Thanks for the code reference. I’ll go load side, and be > prepared for some discussion. > > > > > > Thanks, > > > > > > Garrison > > > > > > > > *From:* re-wrenches-boun...@lists.re-wrenches.org [mailto: > re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *Dave Click > *Sent:* Thursday, February 28, 2013 9:21 AM > *To:* re-wrenches@lists.re-wrenches.org > *Subject:* Re: [RE-wrenches] Conductor Sizing for Supply Side Connection > > > > > > As a note, supply side connections have an extra complication with battery > backup systems. With a regular GT inverter you're just pushing current into > that interconnection point and you can work out easily that you won't have > any overcurrent issues unless you made a big mistake and your inverter > output exceeds the rating of your service conductors. However, with a > battery system you're also potentially pulling current from that point. > Before the battery inverter is installed your main breaker protects your > service conductors, but if the inverter is pulling in 60A and the main > breaker is also operating near its capacity, you could have >240A running > over 200A service conductors with no breakers tripping. You would overwhelm > the capacity of the service [230.23(A)] and no breakers would trip. You > could fix this by replacing your service conductors back to the transformer > (I'm just saying that it's an option) or downsizing the main breaker, and > at that point you're probably better off just making it a load side > connection. I'd go load side and argue with the AHJ to use the 2011 update > mentioned earlier. > > Dave > > > > On 2013/2/28 9:55, Garrison Riegel wrote: > > > > Allen, > > > > > > > > The benefit I see would be to allow for a code compliant load side > connection on a 200A panel with a 200A MB, where the AHJ is on the 2008 NEC > or older and will not listen to your good logic. I don’t think this would > always be the best option, but if backup loads and inverter output were > less than 32A then a 40A OCPD in the main panel should be fine? Since it > sounds like the 60A breaker in the main panel is not a safety issue, but a > design consideration, I suppose I would just prefer flexibility when > possible. > > > > > > > > That said, this AHJ is on the 2008, and the loads will be less than 30A, > but based on this conversation I plan to go with a 60A and try to convince > the AHJ that it will be code compliant in their future! > > > > > > > > Thanks, > > > > > > > > Garrison > > > > > > > > > > > > *From:* re-wrenches-boun...@lists.re-wrenches.org [ > mailto:re-wrenches-boun...@lists.re-wrenches.org] > *On Behalf Of *Allan Sindelar > *Sent:* Thursday, February 28, 2013 8:14 AM > *To:* RE-wrenches > *Subject:* Re: [RE-wrenches] Conductor Sizing for Supply Side Connection > > > > > > > > Garrison, > I don't know why it's not listed as 60A max, but my own internal logic > would ask why it should be. The only benefit I could see for using smaller > than a 60A breaker would be to allow use of #8 conductors (allowed with a > 40A or 50A breaker) instead of the #6 necessary with a 60A breaker. And of > course, you could use a 40A breaker with #6 conductors, so theoretically it > would be fine. I just fail to see any benefit to doing so. > Allan > > > > *Allan Sindelar* > al...@positiveenergysolar.com > NABCEP Certified Photovoltaic Installer > NABCEP Certified Technical Sales Professional > New Mexico EE98J Journeyman Electrician > Founder and Chief Technology Officer > *Positive Energy, Inc.* > 320
Re: [RE-wrenches] Conductor Sizing for Supply Side Connection
Garrison, et al: Another consideration when sizing the POCC OCPD (either load side or supply side) is charging current when the grid power returns and the battery bank is near the LBCO voltage. Bulk charging current and AC pass-through current both must be considered when sizing the POCC OCPD. Regards, Gary Willett Icarus SolarOn Thu, 28 Feb 2013 10:04:51 -0600, Garrison Riegel wrote: Great point Dave. It crossed my mind that it was technically possible, but figured since I would be removing loads off the main panel it was highly unlikely. Thanks for the code reference. I’ll go load side, and be prepared for some discussion. Thanks, Garrison From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Dave ClickSent: Thursday, February 28, 2013 9:21 AMTo: re-wrenches@lists.re-wrenches.orgSubject: Re: [RE-wrenches] Conductor Sizing for Supply Side Connection As a note, supply side connections have an extra complication with battery backup systems. With a regular GT inverter you're just pushing current into that interconnection point and you can work out easily that you won't have any overcurrent issues unless you made a big mistake and your inverter output exceeds the rating of your service conductors. However, with a battery system you're also potentially pulling current from that point. Before the battery inverter is installed your main breaker protects your service conductors, but if the inverter is pulling in 60A and the main breaker is also operating near its capacity, you could have >240A running over 200A service conductors with no breakers tripping. You would overwhelm the capacity of the service [230.23(A)] and no breakers would trip. You could fix this by replacing your service conductors back to the transformer (I'm just saying that it's an option) or downsizing the main breaker, and at that point you're probably better off just making it a load side connection. I'd go load side and argue with the AHJ to use the 2011 update mentioned earlier.Dave On 2013/2/28 9:55, Garrison Riegel wrote: Allen, The benefit I see would be to allow for a code compliant load side connection on a 200A panel with a 200A MB, where the AHJ is on the 2008 NEC or older and will not listen to your good logic. I don’t think this would always be the best option, but if backup loads and inverter output were less than 32A then a 40A OCPD in the main panel should be fine? Since it sounds like the 60A breaker in the main panel is not a safety issue, but a design consideration, I suppose I would just prefer flexibility when possible. That said, this AHJ is on the 2008, and the loads will be less than 30A, but based on this conversation I plan to go with a 60A and try to convince the AHJ that it will be code compliant in their future! Thanks, Garrison From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Allan SindelarSent: Thursday, February 28, 2013 8:14 AMTo: RE-wrenchesSubject: Re: [RE-wrenches] Conductor Sizing for Supply Side Connection Garrison,I don't know why it's not listed as 60A max, but my own internal logic would ask why it should be. The only benefit I could see for using smaller than a 60A breaker would be to allow use of #8 conductors (allowed with a 40A or 50A breaker) instead of the #6 necessary with a 60A breaker. And of course, you could use a 40A breaker with #6 conductors, so theoretically it would be fine. I just fail to see any benefit to doing so.Allan Allan Sindelaral...@positiveenergysolar.comNABCEP Certified Photovoltaic InstallerNABCEP Certified Technical Sales ProfessionalNew Mexico EE98J Journeyman ElectricianFounder and Chief Technology OfficerPositive Energy, Inc.3209 Richards Lane (note new address)Santa Fe, New Mexico 87507505 424-1112www.positiveenergysolar.com On 2/28/2013 6:27 AM, Garrison Riegel wrote: Thanks Allen for clarifying why a 60A is required. I was wondering. The spec does list a surge current of 9000W so I thought that may be the rationale, but even that would only require a 50A, and since this surge occurs during ‘stand-alone mode’ it didn’t seem to apply to the OCPD at the main panel. Your explanation makes more sense, but I wonder why then they don’t list the AC input breaker size as 60A max. If you have few backup loads, and are not on the 2011 NEC, a 40A could theoretically be fine? Thanks all for your thoughts, much appreciated. Garrison From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Allan SindelarSent: Wednesday, February 27, 2013 6:08 PMTo: RE-wrenchesSubject: Re: [RE-wrenches] Conductor Sizing for Supply Side Connection August,The 60A breaker is intended to allow grid power to pass through to the loads in excess
Re: [RE-wrenches] Conductor Sizing for Supply Side Connection
Great point Dave. It crossed my mind that it was technically possible, but figured since I would be removing loads off the main panel it was highly unlikely. Thanks for the code reference. I'll go load side, and be prepared for some discussion. Thanks, Garrison From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Dave Click Sent: Thursday, February 28, 2013 9:21 AM To: re-wrenches@lists.re-wrenches.org Subject: Re: [RE-wrenches] Conductor Sizing for Supply Side Connection As a note, supply side connections have an extra complication with battery backup systems. With a regular GT inverter you're just pushing current into that interconnection point and you can work out easily that you won't have any overcurrent issues unless you made a big mistake and your inverter output exceeds the rating of your service conductors. However, with a battery system you're also potentially pulling current from that point. Before the battery inverter is installed your main breaker protects your service conductors, but if the inverter is pulling in 60A and the main breaker is also operating near its capacity, you could have >240A running over 200A service conductors with no breakers tripping. You would overwhelm the capacity of the service [230.23(A)] and no breakers would trip. You could fix this by replacing your service conductors back to the transformer (I'm just saying that it's an option) or downsizing the main breaker, and at that point you're probably better off just making it a load side connection. I'd go load side and argue with the AHJ to use the 2011 update mentioned earlier. Dave On 2013/2/28 9:55, Garrison Riegel wrote: Allen, The benefit I see would be to allow for a code compliant load side connection on a 200A panel with a 200A MB, where the AHJ is on the 2008 NEC or older and will not listen to your good logic. I don't think this would always be the best option, but if backup loads and inverter output were less than 32A then a 40A OCPD in the main panel should be fine? Since it sounds like the 60A breaker in the main panel is not a safety issue, but a design consideration, I suppose I would just prefer flexibility when possible. That said, this AHJ is on the 2008, and the loads will be less than 30A, but based on this conversation I plan to go with a 60A and try to convince the AHJ that it will be code compliant in their future! Thanks, Garrison From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Allan Sindelar Sent: Thursday, February 28, 2013 8:14 AM To: RE-wrenches Subject: Re: [RE-wrenches] Conductor Sizing for Supply Side Connection Garrison, I don't know why it's not listed as 60A max, but my own internal logic would ask why it should be. The only benefit I could see for using smaller than a 60A breaker would be to allow use of #8 conductors (allowed with a 40A or 50A breaker) instead of the #6 necessary with a 60A breaker. And of course, you could use a 40A breaker with #6 conductors, so theoretically it would be fine. I just fail to see any benefit to doing so. Allan Allan Sindelar <mailto:al...@positiveenergysolar.com> al...@positiveenergysolar.com NABCEP Certified Photovoltaic Installer NABCEP Certified Technical Sales Professional New Mexico EE98J Journeyman Electrician Founder and Chief Technology Officer Positive Energy, Inc. 3209 Richards Lane (note new address) Santa Fe, New Mexico 87507 505 424-1112 www.positiveenergysolar.com <http://www.positiveenergysolar.com/> On 2/28/2013 6:27 AM, Garrison Riegel wrote: Thanks Allen for clarifying why a 60A is required. I was wondering. The spec does list a surge current of 9000W so I thought that may be the rationale, but even that would only require a 50A, and since this surge occurs during 'stand-alone mode' it didn't seem to apply to the OCPD at the main panel. Your explanation makes more sense, but I wonder why then they don't list the AC input breaker size as 60A max. If you have few backup loads, and are not on the 2011 NEC, a 40A could theoretically be fine? Thanks all for your thoughts, much appreciated. Garrison From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Allan Sindelar Sent: Wednesday, February 27, 2013 6:08 PM To: RE-wrenches Subject: Re: [RE-wrenches] Conductor Sizing for Supply Side Connection August, The 60A breaker is intended to allow grid power to pass through to the loads in excess of the inverter's stand-alone output. The point of 705.12 (moved in the 2011 NEC from 690.64 (B)(2)) is to differentiate between load pass-through current and sell current. The amount of current fed into the grid is (4500/230 =) 19.56A, while the amount that can be taken from the grid a
Re: [RE-wrenches] Conductor Sizing for Supply Side Connection
As a note, supply side connections have an extra complication with
battery backup systems. With a regular GT inverter you're just pushing
current into that interconnection point and you can work out easily that
you won't have any overcurrent issues unless you made a big mistake and
your inverter output exceeds the rating of your service conductors.
However, with a battery system you're also potentially pulling current
from that point. Before the battery inverter is installed your main
breaker protects your service conductors, but if the inverter is pulling
in 60A and the main breaker is also operating near its capacity, you
could have >240A running over 200A service conductors with no breakers
tripping. You would overwhelm the capacity of the service [230.23(A)]
and no breakers would trip. You could fix this by replacing your service
conductors back to the transformer (I'm just saying that it's an option)
or downsizing the main breaker, and at that point you're probably better
off just making it a load side connection. I'd go load side and argue
with the AHJ to use the 2011 update mentioned earlier.
Dave
On 2013/2/28 9:55, Garrison Riegel wrote:
Allen,
The benefit I see would be to allow for a code compliant load side
connection on a 200A panel with a 200A MB, where the AHJ is on the
2008 NEC or older and will not listen to your good logic. I don't
think this would always be the best option, but if backup loads and
inverter output were less than 32A then a 40A OCPD in the main panel
should be fine? Since it sounds like the 60A breaker in the main
panel is not a safety issue, but a design consideration, I suppose I
would just prefer flexibility when possible.
That said, this AHJ is on the 2008, and the loads will be less than
30A, but based on this conversation I plan to go with a 60A and try to
convince the AHJ that it will be code compliant in their future!
Thanks,
Garrison
*From:*re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of
*Allan Sindelar
*Sent:* Thursday, February 28, 2013 8:14 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Conductor Sizing for Supply Side Connection
Garrison,
I don't know why it's not listed as 60A max, but my own internal logic
would ask why it should be. The only benefit I could see for using
smaller than a 60A breaker would be to allow use of #8 conductors
(allowed with a 40A or 50A breaker) instead of the #6 necessary with a
60A breaker. And of course, you could use a 40A breaker with #6
conductors, so theoretically it would be fine. I just fail to see any
benefit to doing so.
Allan
*Allan Sindelar*
al...@positiveenergysolar.com <mailto:al...@positiveenergysolar.com>
NABCEP Certified Photovoltaic Installer
NABCEP Certified Technical Sales Professional
New Mexico EE98J Journeyman Electrician
Founder and Chief Technology Officer
*Positive Energy, Inc.*
3209 Richards Lane (note new address)
Santa Fe, New Mexico 87507
*505 424-1112*
www.positiveenergysolar.com <http://www.positiveenergysolar.com/>
On 2/28/2013 6:27 AM, Garrison Riegel wrote:
Thanks Allen for clarifying why a 60A is required. I was
wondering. The spec does list a surge current of 9000W so I
thought that may be the rationale, but even that would only
require a 50A, and since this surge occurs during 'stand-alone
mode' it didn't seem to apply to the OCPD at the main panel. Your
explanation makes more sense, but I wonder why then they don't
list the AC input breaker size as 60A /max/. If you have few
backup loads, and are not on the 2011 NEC, a 40A could
theoretically be fine?
Thanks all for your thoughts, much appreciated.
Garrison
*From:*re-wrenches-boun...@lists.re-wrenches.org
<mailto:re-wrenches-boun...@lists.re-wrenches.org>
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of
*Allan Sindelar
*Sent:* Wednesday, February 27, 2013 6:08 PM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Conductor Sizing for Supply Side
Connection
August,
The 60A breaker is intended to allow grid power to pass through to
the loads in excess of the inverter's stand-alone output. The
point of 705.12 (moved in the 2011 NEC from 690.64 (B)(2)) is to
differentiate between load pass-through current and sell current.
The amount of current fed into the grid is (4500/230 =) 19.56A,
while the amount that can be taken from the grid and passed
through to the load is much greater. If you were limited to a 40A
breaker in order to maintain 120% of a 200A main bus, you'd be
prone to nuisance trips under large cumulative loads.
Allan
*Allan Sindelar*
al...@positiveenergysolar.com <mailto:al...@positiveenergysolar.com>
NABCEP Certified Photovoltaic Installer
NABCEP Certifie
Re: [RE-wrenches] Conductor Sizing for Supply Side Connection
Allen, The benefit I see would be to allow for a code compliant load side connection on a 200A panel with a 200A MB, where the AHJ is on the 2008 NEC or older and will not listen to your good logic. I don't think this would always be the best option, but if backup loads and inverter output were less than 32A then a 40A OCPD in the main panel should be fine? Since it sounds like the 60A breaker in the main panel is not a safety issue, but a design consideration, I suppose I would just prefer flexibility when possible. That said, this AHJ is on the 2008, and the loads will be less than 30A, but based on this conversation I plan to go with a 60A and try to convince the AHJ that it will be code compliant in their future! Thanks, Garrison From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Allan Sindelar Sent: Thursday, February 28, 2013 8:14 AM To: RE-wrenches Subject: Re: [RE-wrenches] Conductor Sizing for Supply Side Connection Garrison, I don't know why it's not listed as 60A max, but my own internal logic would ask why it should be. The only benefit I could see for using smaller than a 60A breaker would be to allow use of #8 conductors (allowed with a 40A or 50A breaker) instead of the #6 necessary with a 60A breaker. And of course, you could use a 40A breaker with #6 conductors, so theoretically it would be fine. I just fail to see any benefit to doing so. Allan Allan Sindelar <mailto:al...@positiveenergysolar.com> al...@positiveenergysolar.com NABCEP Certified Photovoltaic Installer NABCEP Certified Technical Sales Professional New Mexico EE98J Journeyman Electrician Founder and Chief Technology Officer Positive Energy, Inc. 3209 Richards Lane (note new address) Santa Fe, New Mexico 87507 505 424-1112 www.positiveenergysolar.com <http://www.positiveenergysolar.com/> On 2/28/2013 6:27 AM, Garrison Riegel wrote: Thanks Allen for clarifying why a 60A is required. I was wondering. The spec does list a surge current of 9000W so I thought that may be the rationale, but even that would only require a 50A, and since this surge occurs during 'stand-alone mode' it didn't seem to apply to the OCPD at the main panel. Your explanation makes more sense, but I wonder why then they don't list the AC input breaker size as 60A max. If you have few backup loads, and are not on the 2011 NEC, a 40A could theoretically be fine? Thanks all for your thoughts, much appreciated. Garrison From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Allan Sindelar Sent: Wednesday, February 27, 2013 6:08 PM To: RE-wrenches Subject: Re: [RE-wrenches] Conductor Sizing for Supply Side Connection August, The 60A breaker is intended to allow grid power to pass through to the loads in excess of the inverter's stand-alone output. The point of 705.12 (moved in the 2011 NEC from 690.64 (B)(2)) is to differentiate between load pass-through current and sell current. The amount of current fed into the grid is (4500/230 =) 19.56A, while the amount that can be taken from the grid and passed through to the load is much greater. If you were limited to a 40A breaker in order to maintain 120% of a 200A main bus, you'd be prone to nuisance trips under large cumulative loads. Allan Allan Sindelar <mailto:al...@positiveenergysolar.com> al...@positiveenergysolar.com NABCEP Certified Photovoltaic Installer NABCEP Certified Technical Sales Professional New Mexico EE98J Journeyman Electrician Founder and Chief Technology Officer Positive Energy, Inc. 3209 Richards Lane (note new address) Santa Fe, New Mexico 87507 505 424-1112 www.positiveenergysolar.com <http://www.positiveenergysolar.com/> ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Change email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Change email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
Re: [RE-wrenches] Conductor Sizing for Supply Side Connection
Garrison,
I don't know why it's not listed as 60A max, but my own internal
logic would ask why it should be. The only benefit I could see for
using smaller than a 60A breaker would be to allow use of #8
conductors (allowed with a 40A or 50A breaker) instead of the #6
necessary with a 60A breaker. And of course, you could use a 40A
breaker with #6 conductors, so theoretically it would be fine. I
just fail to see any benefit to doing so.
Allan
Allan Sindelar
al...@positiveenergysolar.com
NABCEP Certified Photovoltaic
Installer
NABCEP Certified Technical Sales Professional
New Mexico EE98J Journeyman Electrician
Founder and Chief Technology Officer
Positive Energy, Inc.
3209 Richards Lane (note new address)
Santa Fe, New Mexico 87507
505 424-1112
www.positiveenergysolar.com
On 2/28/2013 6:27 AM, Garrison Riegel wrote:
Thanks Allen
for clarifying why a 60A is required. I was wondering. The
spec does list a surge current of 9000W so I thought that
may be the rationale, but even that would only require a
50A, and since this surge occurs during ‘stand-alone mode’
it didn’t seem to apply to the OCPD at the main panel. Your
explanation makes more sense, but I wonder why then they
don’t list the AC input breaker size as 60A max. If
you have few backup loads, and are not on the 2011 NEC, a
40A could theoretically be fine?
Thanks all for
your thoughts, much appreciated.
Garrison
From:
re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On
Behalf Of Allan Sindelar
Sent: Wednesday, February 27, 2013 6:08 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Conductor Sizing for
Supply Side Connection
August,
The 60A breaker is intended to allow grid power to pass
through to the loads in excess of the inverter's stand-alone
output. The point of 705.12 (moved in the 2011 NEC from
690.64 (B)(2)) is to differentiate between load pass-through
current and sell current. The amount of current fed into the
grid is (4500/230 =) 19.56A, while the amount that can be
taken from the grid and passed through to the load is much
greater. If you were limited to a 40A breaker in order to
maintain 120% of a 200A main bus, you'd be prone to nuisance
trips under large cumulative loads.
Allan
Allan Sindelar
al...@positiveenergysolar.com
NABCEP Certified
Photovoltaic Installer
NABCEP Certified Technical Sales Professional
New Mexico EE98J Journeyman Electrician
Founder and Chief Technology Officer
Positive Energy, Inc.
3209 Richards Lane (note new address)
Santa Fe, New Mexico 87507
505 424-1112
www.positiveenergysolar.com
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Re: [RE-wrenches] Conductor Sizing for Supply Side Connection
Thanks Allen for clarifying why a 60A is required. I was wondering. The spec does list a surge current of 9000W so I thought that may be the rationale, but even that would only require a 50A, and since this surge occurs during 'stand-alone mode' it didn't seem to apply to the OCPD at the main panel. Your explanation makes more sense, but I wonder why then they don't list the AC input breaker size as 60A max. If you have few backup loads, and are not on the 2011 NEC, a 40A could theoretically be fine? Thanks all for your thoughts, much appreciated. Garrison From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Allan Sindelar Sent: Wednesday, February 27, 2013 6:08 PM To: RE-wrenches Subject: Re: [RE-wrenches] Conductor Sizing for Supply Side Connection August, The 60A breaker is intended to allow grid power to pass through to the loads in excess of the inverter's stand-alone output. The point of 705.12 (moved in the 2011 NEC from 690.64 (B)(2)) is to differentiate between load pass-through current and sell current. The amount of current fed into the grid is (4500/230 =) 19.56A, while the amount that can be taken from the grid and passed through to the load is much greater. If you were limited to a 40A breaker in order to maintain 120% of a 200A main bus, you'd be prone to nuisance trips under large cumulative loads. Allan Allan Sindelar <mailto:al...@positiveenergysolar.com> al...@positiveenergysolar.com NABCEP Certified Photovoltaic Installer NABCEP Certified Technical Sales Professional New Mexico EE98J Journeyman Electrician Founder and Chief Technology Officer Positive Energy, Inc. 3209 Richards Lane (note new address) Santa Fe, New Mexico 87507 505 424-1112 www.positiveenergysolar.com <http://www.positiveenergysolar.com/> ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Change email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
Re: [RE-wrenches] Conductor Sizing for Supply Side Connection
Alan, Thanks for the clarification. I believe you and Jeremy are talking about the exception listed on the last paragraph of 705.12(D)(2). I've never used that rule but it is good to know about. When we do battery backup we typically route the critical loads through an external transfer switch rather than through the battery inverter but this definitely has the potential to open up doors and potentially reduce equipment cost. Best, August August Goers Luminalt Energy Corporation 1320 Potrero Avenue San Francisco, CA 94110 m: 415.559.1525 o: 415.641.4000 aug...@luminalt.com *From:* re-wrenches-boun...@lists.re-wrenches.org [mailto: re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *Allan Sindelar *Sent:* Wednesday, February 27, 2013 4:08 PM *To:* RE-wrenches *Subject:* Re: [RE-wrenches] Conductor Sizing for Supply Side Connection August, The 60A breaker is intended to allow grid power to pass through to the loads in excess of the inverter's stand-alone output. The point of 705.12 (moved in the 2011 NEC from 690.64 (B)(2)) is to differentiate between load pass-through current and sell current. The amount of current fed into the grid is (4500/230 =) 19.56A, while the amount that can be taken from the grid and passed through to the load is much greater. If you were limited to a 40A breaker in order to maintain 120% of a 200A main bus, you'd be prone to nuisance trips under large cumulative loads. Allan *Allan Sindelar* al...@positiveenergysolar.com NABCEP Certified Photovoltaic Installer NABCEP Certified Technical Sales Professional New Mexico EE98J Journeyman Electrician Founder and Chief Technology Officer *Positive Energy, Inc.* 3209 Richards Lane (note new address) Santa Fe, New Mexico 87507 *505 424-1112* www.positiveenergysolar.com On 2/27/2013 4:23 PM, August Goers wrote: Jeremy, Good point. Even under the 2008 NEC 690.64(B)(2) you can install up to a 40 Amp breaker on the load side as long as it is on the opposite side of the input feed per 690.64(B)(7). Garrison, do you need a 60 A breaker? I haven't used this product myself, but if the continuous output power is indeed 4500 W then you'd be fine with a 25 or 30 A breaker. Best, August *From:* re-wrenches-boun...@lists.re-wrenches.org [mailto: re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *All Solar, Inc. *Sent:* Wednesday, February 27, 2013 1:50 PM *To:* RE-wrenches *Subject:* Re: [RE-wrenches] Conductor Sizing for Supply Side Connection There is an exception in NEC2011 regarding the point of connection. This may not apply, but you could avoid the supply side. 4500W / 240V = 18.75 x 1.25 = 23.4A, well under the 120% rule. reference 705.12(D)(2) Jeremy All Solar CO,USA - Original Message - *From:* Garrison Riegel *To:* 'RE-wrenches' *Sent:* Wednesday, February 27, 2013 2:15 PM *Subject:* [RE-wrenches] Conductor Sizing for Supply Side Connection Wrenches, On an upcoming job we have a Xantrex XW4548 interconnecting with a 200A service, and I’d very much appreciate some advice if y’all are willing. Since the inverter output OCPD is required to be 60A we are looking at a supply side connection, and I have two questions: 1. Before the point of interconnection the inverter output circuit will first pass through the XW Power Distribution Panel and inverter bypass, which is essentially a 60A breaker. The service disconnect for the supply side connection will also be fused at 60A. Does the 120% rule apply to the conductor between these two OCPDs? Or since this is a supply side connection in accordance with 690.64(A), 690.64(B)(2) will not apply? [this AHJ is on the 2008 NEC] 2. Can anyone recommend a reliable insulation piercing tap connector? Or would you recommend something else entirely for a residential supply side connection? Thanks in advance, Garrison 847-677-0950 Solar Service Inc. -- ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Change email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Change email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org ___ List sponsored by Home Power magazi
Re: [RE-wrenches] Conductor Sizing for Supply Side Connection
August,
The 60A breaker is intended to allow grid power to pass through to
the loads in excess of the inverter's stand-alone output. The
point of 705.12 (moved in the 2011 NEC from 690.64 (B)(2)) is to
differentiate between load pass-through current and sell current.
The amount of current fed into the grid is (4500/230 =) 19.56A,
while the amount that can be taken from the grid and passed
through to the load is much greater. If you were limited to a 40A
breaker in order to maintain 120% of a 200A main bus, you'd be
prone to nuisance trips under large cumulative loads.
Allan
Allan Sindelar
al...@positiveenergysolar.com
NABCEP Certified Photovoltaic
Installer
NABCEP Certified Technical Sales Professional
New Mexico EE98J Journeyman Electrician
Founder and Chief Technology Officer
Positive Energy, Inc.
3209 Richards Lane (note new address)
Santa Fe, New Mexico 87507
505 424-1112
www.positiveenergysolar.com
On 2/27/2013 4:23 PM, August Goers wrote:
Jeremy,
Good point.
Even under the 2008 NEC 690.64(B)(2) you can install up to a
40 Amp breaker on the load side as long as it is on the
opposite side of the input feed per 690.64(B)(7). Garrison,
do you need a 60 A breaker?
I haven't used
this product myself, but if the continuous output power is
indeed 4500 W then you'd be fine with a 25 or 30 A breaker.
Best,
August
From:
re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org]
On Behalf Of All Solar, Inc.
Sent: Wednesday, February 27, 2013 1:50 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Conductor Sizing for
Supply Side Connection
There
is an exception in NEC2011 regarding the point of
connection. This may not apply, but you could avoid the
supply side. 4500W / 240V = 18.75 x 1.25 = 23.4A, well
under the 120% rule. reference 705.12(D)(2)
Jeremy
All
Solar
CO,USA
-
Original Message -
From:
Garrison Riegel
To:
'RE-wrenches'
Sent:
Wednesday, February 27, 2013 2:15 PM
Subject:
[RE-wrenches] Conductor Sizing for Supply Side
Connection
Wrenches,
On an upcoming job we have a Xantrex
XW4548 interconnecting with a 200A service, and I’d very
much appreciate some advice if y’all are willing.
Since the inverter output OCPD is
required to be 60A we are looking at a supply side
connection, and I have two questions:
1. Before the
point of interconnection the inverter output circuit will
first pass through the XW Power Distribution Panel and
inverter bypass, which is essentially a 60A breaker. The
service disconnect for the supply side connection will also
be fused at 60A. Does the 120% rule apply to the conductor
between these two OCPDs? Or since this is a supply side
connection in accordance with 690.64(A), 690.64(B)(2) will
not apply? [this AHJ is on the 2008 NEC]
2. Can anyone
recommend a reliable insulation piercing tap connector? Or
would you recommend something else entirely for a
residential supply side connection?
Thanks in advance,
Garrison
847-677-0950
Solar Service Inc.
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Re: [RE-wrenches] Conductor Sizing for Supply Side Connection
Jeremy, Good point. Even under the 2008 NEC 690.64(B)(2) you can install up to a 40 Amp breaker on the load side as long as it is on the opposite side of the input feed per 690.64(B)(7). Garrison, do you need a 60 A breaker? I haven't used this product myself, but if the continuous output power is indeed 4500 W then you'd be fine with a 25 or 30 A breaker. Best, August *From:* re-wrenches-boun...@lists.re-wrenches.org [mailto: re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *All Solar, Inc. *Sent:* Wednesday, February 27, 2013 1:50 PM *To:* RE-wrenches *Subject:* Re: [RE-wrenches] Conductor Sizing for Supply Side Connection There is an exception in NEC2011 regarding the point of connection. This may not apply, but you could avoid the supply side. 4500W / 240V = 18.75 x 1.25 = 23.4A, well under the 120% rule. reference 705.12(D)(2) Jeremy All Solar CO,USA - Original Message - *From:* Garrison Riegel *To:* 'RE-wrenches' *Sent:* Wednesday, February 27, 2013 2:15 PM *Subject:* [RE-wrenches] Conductor Sizing for Supply Side Connection Wrenches, On an upcoming job we have a Xantrex XW4548 interconnecting with a 200A service, and I’d very much appreciate some advice if y’all are willing. Since the inverter output OCPD is required to be 60A we are looking at a supply side connection, and I have two questions: 1. Before the point of interconnection the inverter output circuit will first pass through the XW Power Distribution Panel and inverter bypass, which is essentially a 60A breaker. The service disconnect for the supply side connection will also be fused at 60A. Does the 120% rule apply to the conductor between these two OCPDs? Or since this is a supply side connection in accordance with 690.64(A), 690.64(B)(2) will not apply? [this AHJ is on the 2008 NEC] 2. Can anyone recommend a reliable insulation piercing tap connector? Or would you recommend something else entirely for a residential supply side connection? Thanks in advance, Garrison 847-677-0950 Solar Service Inc. -- ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Change email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Change email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
Re: [RE-wrenches] Conductor Sizing for Supply Side Connection
Thanks August. I couldn't get the attachment to open, but I see what you're saying. You do bring up a good point about the AHJ as well. Few here have seen solar, and fewer are familiar with 690 so anything out of the ordinary usually gets flagged. As Jeremy points out the 2011 NEC would allow this as a load side connection, so maybe I should spend my energy trying to convince them to let us follow the current Code instead. Thanks much, Garrison From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of August Goers Sent: Wednesday, February 27, 2013 3:43 PM To: RE-wrenches Subject: Re: [RE-wrenches] Conductor Sizing for Supply Side Connection Hi Garrison, In my opinion you only need to size the conductors to the overcurrent protection. Bill Brooks addressed a similar question of mine a few months ago - I've attached the email here. If you do a node analysis (ie see what would happen under both normal operation and fault conditions at any given point) you'll see that the current at any given point along the wire path will never exceed the breaker ratings on either side (or the higher of the two if they're different). It is a different story from what the 120% rule is addressing - in that case the current feeding into a busbar has the potential of being supplied by both the main breaker and the solar breaker thus potentially exceeding the bus capacity. I've used insulation piercing connectors from Burndy and Ilso with good results. Ilsco is called KUP-L-TAP and part number IPC-4/0-2/0 is a common one. You'll need to find the part number that best matches your wire size. It's a bit of a separate issue, but I've found that many jurisdictions are very critical of supply side connections and can start to ask questions about whether the whole setup is listed for the purpose. It is nearly impossible to get the manufacturer to list the entire service and line tap in my experience. You might want to look into that if you think your jurisdiction might have similar concerns. Good luck! Best, August August Goers Luminalt Energy Corporation 1320 Potrero Avenue San Francisco, CA 94110 m: 415.559.1525 o: 415.641.4000 aug...@luminalt.com From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Garrison Riegel Sent: Wednesday, February 27, 2013 1:15 PM To: 'RE-wrenches' Subject: [RE-wrenches] Conductor Sizing for Supply Side Connection Wrenches, On an upcoming job we have a Xantrex XW4548 interconnecting with a 200A service, and I'd very much appreciate some advice if y'all are willing. Since the inverter output OCPD is required to be 60A we are looking at a supply side connection, and I have two questions: 1. Before the point of interconnection the inverter output circuit will first pass through the XW Power Distribution Panel and inverter bypass, which is essentially a 60A breaker. The service disconnect for the supply side connection will also be fused at 60A. Does the 120% rule apply to the conductor between these two OCPDs? Or since this is a supply side connection in accordance with 690.64(A), 690.64(B)(2) will not apply? [this AHJ is on the 2008 NEC] 2. Can anyone recommend a reliable insulation piercing tap connector? Or would you recommend something else entirely for a residential supply side connection? Thanks in advance, Garrison 847-677-0950 Solar Service Inc. ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Change email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
Re: [RE-wrenches] Conductor Sizing for Supply Side Connection
There is an exception in NEC2011 regarding the point of connection. This may not apply, but you could avoid the supply side. 4500W / 240V = 18.75 x 1.25 = 23.4A, well under the 120% rule. reference 705.12(D)(2) Jeremy All Solar CO,USA - Original Message - From: Garrison Riegel To: 'RE-wrenches' Sent: Wednesday, February 27, 2013 2:15 PM Subject: [RE-wrenches] Conductor Sizing for Supply Side Connection Wrenches, On an upcoming job we have a Xantrex XW4548 interconnecting with a 200A service, and I'd very much appreciate some advice if y'all are willing. Since the inverter output OCPD is required to be 60A we are looking at a supply side connection, and I have two questions: 1. Before the point of interconnection the inverter output circuit will first pass through the XW Power Distribution Panel and inverter bypass, which is essentially a 60A breaker. The service disconnect for the supply side connection will also be fused at 60A. Does the 120% rule apply to the conductor between these two OCPDs? Or since this is a supply side connection in accordance with 690.64(A), 690.64(B)(2) will not apply? [this AHJ is on the 2008 NEC] 2. Can anyone recommend a reliable insulation piercing tap connector? Or would you recommend something else entirely for a residential supply side connection? Thanks in advance, Garrison 847-677-0950 Solar Service Inc. -- ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Change email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Change email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
Re: [RE-wrenches] Conductor Sizing for Supply Side Connection
Hi Garrison, In my opinion you only need to size the conductors to the overcurrent protection. Bill Brooks addressed a similar question of mine a few months ago - I've attached the email here. If you do a node analysis (ie see what would happen under both normal operation and fault conditions at any given point) you'll see that the current at any given point along the wire path will never exceed the breaker ratings on either side (or the higher of the two if they're different). It is a different story from what the 120% rule is addressing - in that case the current feeding into a busbar has the potential of being supplied by both the main breaker and the solar breaker thus potentially exceeding the bus capacity. I've used insulation piercing connectors from Burndy and Ilso with good results. Ilsco is called KUP-L-TAP and part number IPC-4/0-2/0 is a common one. You'll need to find the part number that best matches your wire size. It's a bit of a separate issue, but I've found that many jurisdictions are very critical of supply side connections and can start to ask questions about whether the whole setup is listed for the purpose. It is nearly impossible to get the manufacturer to list the entire service and line tap in my experience. You might want to look into that if you think your jurisdiction might have similar concerns. Good luck! Best, August August Goers Luminalt Energy Corporation 1320 Potrero Avenue San Francisco, CA 94110 m: 415.559.1525 o: 415.641.4000 aug...@luminalt.com *From:* re-wrenches-boun...@lists.re-wrenches.org [mailto: re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *Garrison Riegel *Sent:* Wednesday, February 27, 2013 1:15 PM *To:* 'RE-wrenches' *Subject:* [RE-wrenches] Conductor Sizing for Supply Side Connection Wrenches, On an upcoming job we have a Xantrex XW4548 interconnecting with a 200A service, and I’d very much appreciate some advice if y’all are willing. Since the inverter output OCPD is required to be 60A we are looking at a supply side connection, and I have two questions: 1. Before the point of interconnection the inverter output circuit will first pass through the XW Power Distribution Panel and inverter bypass, which is essentially a 60A breaker. The service disconnect for the supply side connection will also be fused at 60A. Does the 120% rule apply to the conductor between these two OCPDs? Or since this is a supply side connection in accordance with 690.64(A), 690.64(B)(2) will not apply? [this AHJ is on the 2008 NEC] 2. Can anyone recommend a reliable insulation piercing tap connector? Or would you recommend something else entirely for a residential supply side connection? Thanks in advance, Garrison 847-677-0950 Solar Service Inc. --- Begin Message --- Andy, August, and Eric, There will likely be significant changes in the 2014 NEC to clarify the situation you are discussing. Fault current has very little to do with this issue. The key distinction was used in my proposal to the 2014 NEC that removed the statement "and conductor" in 705.12(D) since conductors are treated very differently in the NEC. We in 690 are the ones that got this messed up. The issue with conductors are taps. With two sources feeding a tap, the sum of the feeder breakers would have to be taken into account in sizing the tap. This does NOT mean that the tap is a full size conductor. The tap rule determines the size and the new proposal simply requires you to use both the feeder breaker and the PV breaker in sizing the tap. This assumes that both breakers are feeding the tap in the event of fault on the tap and that there would be no problem clearing that fault. If fault current was used as an argument for oversizing (it is wrong), it only has relevance in the tap scenario. A fault in a feeder with no taps does not allow the sum of the currents to flow anywhere but where the fault is-the rest of the conductor is undamaged in a fault. As was pointed out, in a fault, the PV inverter will shut down in a few cycles leaving no contribution from the inverter anyway. Don't even bother thinking about high impedance faults-the NEC does little to deal with these types of faults other than to require ground fault protectors on all services 1000A and up. Sizing a conductor for the sum of two breakers on opposite ends of a feeder seems to be what the code says, but it is totally ABSURD from a technical point of view. John's articles were merely pointing out that the code language seems to be telling us to do this, regardless of whether it makes technical sense. The 2014 NEC will do away with this craziness. Bill. From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Andrew Truitt Sent: Monday, May 07, 2012 11:24 AM To: RE-wrenches Subject: Re: [RE-wrenches] 120% Ru
[RE-wrenches] Conductor Sizing for Supply Side Connection
Wrenches, On an upcoming job we have a Xantrex XW4548 interconnecting with a 200A service, and I'd very much appreciate some advice if y'all are willing. Since the inverter output OCPD is required to be 60A we are looking at a supply side connection, and I have two questions: 1. Before the point of interconnection the inverter output circuit will first pass through the XW Power Distribution Panel and inverter bypass, which is essentially a 60A breaker. The service disconnect for the supply side connection will also be fused at 60A. Does the 120% rule apply to the conductor between these two OCPDs? Or since this is a supply side connection in accordance with 690.64(A), 690.64(B)(2) will not apply? [this AHJ is on the 2008 NEC] 2. Can anyone recommend a reliable insulation piercing tap connector? Or would you recommend something else entirely for a residential supply side connection? Thanks in advance, Garrison 847-677-0950 Solar Service Inc. ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Change email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
