Re: [RE-wrenches] cable spacing in trenches

2011-11-06 Thread Ray Walters 

Drake;

I had trouble finding that reference, then I found it in the back in 
Annex B. I think that would apply to the ampacity of the DC line, but 
then for the 12.47 Kv line, I believe you would need Figure 310.60 which 
then references Tables 310.60 C (77) thru Table 310.60 c (86)
Without knowing more details, it looks like Jerry would need 24" spacing 
(see details 6,8, or 10).
This seems like an issue that you'd want a PE to double check and sign 
off on, as that is a fairly high AC voltage, and there could possibly be 
a significant induced AC voltage on the DC line (especially if its a 
long shared ditch).


Ray Walters

On 11/6/2011 8:36 AM, Drake wrote:

Check out Figure Figure B.310.15(B)(2)(1)



At 07:43 AM 11/4/2011, you wrote:
Separation is an issue the NEC does not address clearly .However, 
please make sure you allow adequate room to repair the conduit if 
damaged, and 12' seems to be the magic number. I lso had no luck 
looking in 490.


NEC 300.4(C)(2)(e) also seems a bit relevant where it allows for 
conductors of different voltage ratings in manholes "if the 
conductors of each system are permanently and effectively separated 
from the conductors of the other systems...", but again this may be 
referring to separate trenches with different system voltage ratings 
entering the same manhole for tapping, allowing access for 
maintenance or other uses.




On Thu, Nov 3, 2011 at 5:42 PM, Jerry Caldwell > wrote:


Can anyone direct me to the NEC article that stipulates how many
inches of separation must be between cables operating at
different voltages?

I have a project with PV combiner box home runs at 1,000 volts DC
in the same trench with 12.47 kV cables.  Table 300.5 shows
minimum cover requirements for direct burial cables, but this is
the distance beneath grade the cables must be.  Is there anywhere
in the code that calls for a minimum separation distance between
cables at different voltages?

Thanks,
Jerry Caldwell




From: Marco Mangelsdorf mailto:ma...@pvthawaii.com>>
To: 'RE-wrenches' mailto:re-wrenches@lists.re-wrenches.org>>
Sent: Thursday, November 3, 2011 2:27 PM
Subject: [RE-wrenches] under performing Enphase inverters

For the first time, several weeks ago, after 40-50 Enphase
installs, we've come across at least two M210s that we putting
out consistently lower outputs than their immediate neighbors.

We replaced the two mods first, which made no difference.  Then,
in consultation with Enphase, replaced the M210s.  After
replacing them, the power output was as it should be.

Now I've got another suspect system with several underperforming
mods out of (36).

Has anyone else had this experience?

Thanks,
marco


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Drake Chamberlin
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CO license 3773
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Re: [RE-wrenches] cable spacing in trenches

2011-11-06 Thread Drake 

Check out Figure Figure B.310.15(B)(2)(1)



At 07:43 AM 11/4/2011, you wrote:
Separation is an issue the NEC does not address clearly .However, 
please make sure you allow adequate room to repair the conduit if 
damaged, and 12' seems to be the magic number. I lso had no luck 
looking in 490.


NEC 300.4(C)(2)(e) also seems a bit relevant where it allows for 
conductors of different voltage ratings in manholes "if the 
conductors of each system are permanently and effectively separated 
from the conductors of the other systems...", but again this may be 
referring to separate trenches with different system voltage ratings 
entering the same manhole for tapping, allowing access for 
maintenance or other uses.




On Thu, Nov 3, 2011 at 5:42 PM, Jerry Caldwell 
<solarcow...@yahoo.com> wrote:
Can anyone direct me to the NEC article that stipulates how many 
inches of separation must be between cables operating at different voltages?


I have a project with PV combiner box home runs at 1,000 volts DC in 
the same trench with 12.47 kV cables.  Table 300.5 shows minimum 
cover requirements for direct burial cables, but this is the 
distance beneath grade the cables must be.  Is there anywhere in the 
code that calls for a minimum separation distance between cables at 
different voltages?


Thanks,
Jerry Caldwell




From: Marco Mangelsdorf <ma...@pvthawaii.com>
To: 'RE-wrenches' 
<re-wrenches@lists.re-wrenches.org>

Sent: Thursday, November 3, 2011 2:27 PM
Subject: [RE-wrenches] under performing Enphase inverters

For the first time, several weeks ago, after 40-50 Enphase installs, 
we've come across at least two M210s that we putting out 
consistently lower outputs than their immediate neighbors.


We replaced the two mods first, which made no difference.  Then, in 
consultation with Enphase, replaced the M210s.  After replacing 
them, the power output was as it should be.


Now I've got another suspect system with several underperforming 
mods out of (36).


Has anyone else had this experience?

Thanks,
marco


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CO license 3773
NABCEP Certified PV
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Re: [RE-wrenches] cable spacing in trenches

2011-11-04 Thread James Rudolph 
Separation is an issue the NEC does not address clearly .However, please
make sure you allow adequate room to repair the conduit if damaged, and 12'
seems to be the magic number. I lso had no luck looking in 490.

NEC 300.4(C)(2)(e) also seems a bit relevant where it allows for conductors
of different voltage ratings in manholes "if the conductors of each system
are permanently and effectively separated from the conductors of the other
systems...", but again this may be referring to separate trenches with
different system voltage ratings entering the same manhole for tapping,
allowing access for maintenance or other uses.



On Thu, Nov 3, 2011 at 5:42 PM, Jerry Caldwell wrote:

> Can anyone direct me to the NEC article that stipulates how many inches of
> separation must be between cables operating at different voltages?
>
> I have a project with PV combiner box home runs at 1,000 volts DC in the
> same trench with 12.47 kV cables.  Table 300.5 shows minimum cover
> requirements for direct burial cables, but this is the distance beneath
> grade the cables must be.  Is there anywhere in the code that calls for a
> minimum separation distance between cables at different voltages?
>
> Thanks,
> Jerry Caldwell
>
>
>
> --
> *From:* Marco Mangelsdorf 
> *To:* 'RE-wrenches' 
> *Sent:* Thursday, November 3, 2011 2:27 PM
> *Subject:* [RE-wrenches] under performing Enphase inverters
>
>   For the first time, several weeks ago, after 40-50 Enphase installs,
> we’ve come across at least two M210s that we putting out consistently lower
> outputs than their immediate neighbors.
>
> We replaced the two mods first, which made no difference.  Then, in
> consultation with Enphase, replaced the M210s.  After replacing them, the
> power output was as it should be.
>
> Now I’ve got another suspect system with several underperforming mods out
> of (36).
>
> Has anyone else had this experience?
>
> Thanks,
> marco
>
>
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*
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Re: [RE-wrenches] cable spacing in trenches

2011-11-03 Thread bob ellison 
What are you running for combiner boxes and wire to run at 1000 volts?

Seems that I remember that fuses are only good for 600 volts and most boxes the 
same limit? 

What are you using?

 

Just wondering,

Bob Ellison 

 

From: re-wrenches-boun...@lists.re-wrenches.org 
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Jerry Caldwell
Sent: Thursday, November 03, 2011 5:42 PM
To: RE-wrenches
Subject: [RE-wrenches] cable spacing in trenches

 

Can anyone direct me to the NEC article that stipulates how many inches of 
separation must be between cables operating at different voltages?

 

I have a project with PV combiner box home runs at 1,000 volts DC in the same 
trench with 12.47 kV cables.  Table 300.5 shows minimum cover requirements for 
direct burial cables, but this is the distance beneath grade the cables must 
be.  Is there anywhere in the code that calls for a minimum separation distance 
between cables at different voltages?

 

Thanks,

Jerry Caldwell

 

 

 

  _  

From: Marco Mangelsdorf 
To: 'RE-wrenches' 
Sent: Thursday, November 3, 2011 2:27 PM
Subject: [RE-wrenches] under performing Enphase inverters

For the first time, several weeks ago, after 40-50 Enphase installs, we’ve come 
across at least two M210s that we putting out consistently lower outputs than 
their immediate neighbors.

 

We replaced the two mods first, which made no difference.  Then, in 
consultation with Enphase, replaced the M210s.  After replacing them, the power 
output was as it should be.

 

Now I’ve got another suspect system with several underperforming mods out of 
(36).

 

Has anyone else had this experience?

 

Thanks,

marco

 


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