Re: [AFMUG] -48V kicking the dead horse

[Robert]

But what about Low voltage cable...  Is smooth hot or cold or ridged hot 
or cold?  So many choices... LOL..


On 1/8/24 9:39 AM, dmmoff...@gmail.com wrote:

I concur with the wire color problem.

* My current employer pays big bucks to a low voltage guy who wires up our
sites.  His work is absolutely beautiful.  It's like friggin artwork.
He uses black for return (+) and green for ground.  Then since most of our
equipment has dual power supplies he uses red and blue for the "A" hot and
"B" hot.  I assume his employer trained him that way for a reason and that's
probably common.

* I was taught in childhood that red is positive, so that's what I have
always done.  I'm not philosophically opposed to the idea that red is "hot",
but that's just now how I learned it.

* https://ztlabels.com/blogs/news/dc-power-circuit-wiring-color-codes
This site advises that for 2-wire DC with positive ground is white for
positive and black for negative.  Someone apparently thinks that's the right
way.  The same site points out that the only color called out specifically
in the NEC is green or green/yellow for ground.  Everything else is just the
convention people landed on.

Out in the wild you might see anything so there is and will always be a
multi-meter in my everyday toolkit.

-Adam



-Original Message-
From: AF  On Behalf Of Ken Hohhof
Sent: Monday, January 08, 2024 12:01 PM
To: 'AnimalFarm Microwave Users Group' 
Subject: Re: [AFMUG] -48V kicking the dead horse

What I can never decide on is wire colors.  Especially when using red/black
zipcord or tray cable.  People expect red to be +, but they also expect
black to be ground (except electricians who expect black to be hot and white
to be neutral and green or green/yellow to be ground).  And how to
differentiate battery wiring from load wiring.  I have not found an ideal
solution other than labels.

-Original Message-
From: AF  On Behalf Of Bill Prince
Sent: Monday, January 8, 2024 10:45 AM
To: af@af.afmug.com
Subject: Re: [AFMUG] -48V kicking the dead horse

Yes. -48VDC means the negative side is hot, and the positive side is ground
(or return).

You can mix +48VDC and -48VDC if you know what you're doing. It helps a
bunch if the equipment floats logic ground. You need to check to see if your
equipment isolates logic from the supply voltage.

Yes. Batteries can be grounded either way. They don't care.

bp


On 1/8/2024 8:25 AM, Mark - Myakka Technologies wrote:

I know we have been though this many times and I thought I understood it.

-48VDC is the Negative side being HOT, correct?

It is BAD to try to mix -48VDC and 48VDC

There is no such thing as a -48V battery.  A battery is a battery,

correct?

How about the ICT Platinum power supplies.  They show as 48VDC, can
they

be used on -48VDC equipment?

I remember Check saying something about a way to test to see if a
piece of

equipment that is Neg 48VDC is truly grounded as Neg 48VDC.


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   Mark  mailto:m...@mailmt.com

Myakka Communications
www.Myakka.com



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Re: [AFMUG] -48V kicking the dead horse

[Chuck McCown via AF]

480 is 277 to ground/neutral and you can find lots of 277 stuff.  Even 277-120 
control transformers are pretty common.  I would not be surprised to see Mean 
Wells and Tracos having models that will take up to 277.  

Best Regards,
Chuck McCown

McCown Technology Corporation 
8401 N Commerce Dr
Lake Point, Utah 84074
801-250-9503 Office
435-830-4306 Cell
www.mccowntech.com
www.microtrench.pro
www.terabitnetworks.com

From: Ken Hohhof 
Sent: Monday, January 8, 2024 3:06 PM
To: 'AnimalFarm Microwave Users Group' 
Subject: Re: [AFMUG] -48V kicking the dead horse

We run into this at farms and grain elevators that often have 240 or 480 
3-phase.  We are on the grain leg at one farm where there is only the 3 legs no 
neutral.  We checked with Phoenix Contact and the power supply we used can 
accept L1 and L2 on the terminals labeled L and N (actually a Trio DC  UPS, 
this is an old old site).  Not sure how common this is, or if our Mean Wells 
and Tracos would get fried if we tried that.  I wish they wouldn’t label one 
side N if it doesn’t actually have to be the neutral.

 

Most of these sites have an indoor transformer for their 120V lighting and 
convenience outlets.

 

From: AF  On Behalf Of Chuck McCown via AF
Sent: Monday, January 8, 2024 3:55 PM
To: AnimalFarm Microwave Users Group 
Cc: ch...@go-mtc.com
Subject: Re: [AFMUG] -48V kicking the dead horse

 

Another option, 208 Y but 32 volt boost transformers on devices that need 240.  
Have done that before too.  I always consider boost and buck a slick trick.  

 

 

From: Chuck McCown via AF 

Sent: Monday, January 8, 2024 2:43 PM

To: AnimalFarm Microwave Users Group 

Cc: ch...@go-mtc.com 

Subject: Re: [AFMUG] -48V kicking the dead horse

 

You a few choices for 3 phase mixed with 120 single phase.  Stinger center 
tapped winding on a Delta lets you have single phase 120/240 between two legs 
of the delta.  

But this also means you have 240 three phase all the way around where many 3 
phase loads are nominally spec’d at 208.  Probably not a problem but could be 
for some loads.

You also have one leg that is 208 to ground that you might accidentally connect 
to a 120 device.  That is the high leg.  

 

Another choice is a 208 Y configuration.  Each leg is 120 to ground but two of 
those 120 legs are 208 across them instead of 240.  While many 240 loads will 
be OK with 208 some will not.  All your 208 3 phase loads will be happy.  

 

The third choice is a 208 to 240 center tapped transformer.  Then your 208 can 
stay 208 and you can still get true 120/240.  The only downside other than the 
extra expense is the imbalance it puts on the 3 phase line.   My shop is full 
of transformers.  480 to 208.  480 to 240 single phase.  Etc.  

 

Or you could have the power company give you 3 phase and single phase service 
without all of this other baloney.  

 

 

 

From: Mark Radabaugh 

Sent: Monday, January 8, 2024 2:18 PM

To: AnimalFarm Microwave Users Group 

Subject: Re: [AFMUG] -48V kicking the dead horse

 

 





  On Jan 8, 2024, at 1:54 PM, Ken Hohhof  wrote:

   

  What I always have a hard time wrapping my head around is 240/120/208 wild 
leg delta.

   

 

I don’t think that one is hard to understand, other then the ‘why the hell did 
someone center tap a delta let anyway?Ok, I have designed systems that way 
but eventually somebody will blow something up with it given enough time.

 

(it’s useful when you need small quantities of single phase power in an 
otherwise 3 phase system)

 

Mark

 




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Re: [AFMUG] -48V kicking the dead horse

[Ken Hohhof]

We run into this at farms and grain elevators that often have 240 or 480 
3-phase.  We are on the grain leg at one farm where there is only the 3 legs no 
neutral.  We checked with Phoenix Contact and the power supply we used can 
accept L1 and L2 on the terminals labeled L and N (actually a Trio DC  UPS, 
this is an old old site).  Not sure how common this is, or if our Mean Wells 
and Tracos would get fried if we tried that.  I wish they wouldn’t label one 
side N if it doesn’t actually have to be the neutral.

 

Most of these sites have an indoor transformer for their 120V lighting and 
convenience outlets.

 

From: AF  On Behalf Of Chuck McCown via AF
Sent: Monday, January 8, 2024 3:55 PM
To: AnimalFarm Microwave Users Group 
Cc: ch...@go-mtc.com
Subject: Re: [AFMUG] -48V kicking the dead horse

 

Another option, 208 Y but 32 volt boost transformers on devices that need 240.  
Have done that before too.  I always consider boost and buck a slick trick.  

 

 

From: Chuck McCown via AF 

Sent: Monday, January 8, 2024 2:43 PM

To: AnimalFarm Microwave Users Group 

Cc: ch...@go-mtc.com   

Subject: Re: [AFMUG] -48V kicking the dead horse

 

You a few choices for 3 phase mixed with 120 single phase.  Stinger center 
tapped winding on a Delta lets you have single phase 120/240 between two legs 
of the delta.  

But this also means you have 240 three phase all the way around where many 3 
phase loads are nominally spec’d at 208.  Probably not a problem but could be 
for some loads.

You also have one leg that is 208 to ground that you might accidentally connect 
to a 120 device.  That is the high leg.  

 

Another choice is a 208 Y configuration.  Each leg is 120 to ground but two of 
those 120 legs are 208 across them instead of 240.  While many 240 loads will 
be OK with 208 some will not.  All your 208 3 phase loads will be happy.  

 

The third choice is a 208 to 240 center tapped transformer.  Then your 208 can 
stay 208 and you can still get true 120/240.  The only downside other than the 
extra expense is the imbalance it puts on the 3 phase line.   My shop is full 
of transformers.  480 to 208.  480 to 240 single phase.  Etc.  

 

Or you could have the power company give you 3 phase and single phase service 
without all of this other baloney.  

 

 

 

From: Mark Radabaugh 

Sent: Monday, January 8, 2024 2:18 PM

To: AnimalFarm Microwave Users Group 

Subject: Re: [AFMUG] -48V kicking the dead horse

 

 





On Jan 8, 2024, at 1:54 PM, Ken Hohhof mailto:khoh...@kwom.com> > wrote:

 

What I always have a hard time wrapping my head around is 240/120/208 wild leg 
delta.

 

 

I don’t think that one is hard to understand, other then the ‘why the hell did 
someone center tap a delta let anyway?Ok, I have designed systems that way 
but eventually somebody will blow something up with it given enough time.

 

(it’s useful when you need small quantities of single phase power in an 
otherwise 3 phase system)

 

Mark

 

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Re: [AFMUG] -48V kicking the dead horse

[Chuck McCown via AF]

Another option, 208 Y but 32 volt boost transformers on devices that need 240.  
Have done that before too.  I always consider boost and buck a slick trick.  


From: Chuck McCown via AF 
Sent: Monday, January 8, 2024 2:43 PM
To: AnimalFarm Microwave Users Group 
Cc: ch...@go-mtc.com 
Subject: Re: [AFMUG] -48V kicking the dead horse

You a few choices for 3 phase mixed with 120 single phase.  Stinger center 
tapped winding on a Delta lets you have single phase 120/240 between two legs 
of the delta.  
But this also means you have 240 three phase all the way around where many 3 
phase loads are nominally spec’d at 208.  Probably not a problem but could be 
for some loads.
You also have one leg that is 208 to ground that you might accidentally connect 
to a 120 device.  That is the high leg.  

Another choice is a 208 Y configuration.  Each leg is 120 to ground but two of 
those 120 legs are 208 across them instead of 240.  While many 240 loads will 
be OK with 208 some will not.  All your 208 3 phase loads will be happy.  

The third choice is a 208 to 240 center tapped transformer.  Then your 208 can 
stay 208 and you can still get true 120/240.  The only downside other than the 
extra expense is the imbalance it puts on the 3 phase line.   My shop is full 
of transformers.  480 to 208.  480 to 240 single phase.  Etc.  

Or you could have the power company give you 3 phase and single phase service 
without all of this other baloney.  



From: Mark Radabaugh 
Sent: Monday, January 8, 2024 2:18 PM
To: AnimalFarm Microwave Users Group 
Subject: Re: [AFMUG] -48V kicking the dead horse




  On Jan 8, 2024, at 1:54 PM, Ken Hohhof  wrote:

  What I always have a hard time wrapping my head around is 240/120/208 wild 
leg delta.
   


I don’t think that one is hard to understand, other then the ‘why the hell did 
someone center tap a delta let anyway?Ok, I have designed systems that way 
but eventually somebody will blow something up with it given enough time.

(it’s useful when you need small quantities of single phase power in an 
otherwise 3 phase system)

Mark





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Re: [AFMUG] -48V kicking the dead horse

[Chuck McCown via AF]

You a few choices for 3 phase mixed with 120 single phase.  Stinger center 
tapped winding on a Delta lets you have single phase 120/240 between two legs 
of the delta.  
But this also means you have 240 three phase all the way around where many 3 
phase loads are nominally spec’d at 208.  Probably not a problem but could be 
for some loads.
You also have one leg that is 208 to ground that you might accidentally connect 
to a 120 device.  That is the high leg.  

Another choice is a 208 Y configuration.  Each leg is 120 to ground but two of 
those 120 legs are 208 across them instead of 240.  While many 240 loads will 
be OK with 208 some will not.  All your 208 3 phase loads will be happy.  

The third choice is a 208 to 240 center tapped transformer.  Then your 208 can 
stay 208 and you can still get true 120/240.  The only downside other than the 
extra expense is the imbalance it puts on the 3 phase line.   My shop is full 
of transformers.  480 to 208.  480 to 240 single phase.  Etc.  

Or you could have the power company give you 3 phase and single phase service 
without all of this other baloney.  



From: Mark Radabaugh 
Sent: Monday, January 8, 2024 2:18 PM
To: AnimalFarm Microwave Users Group 
Subject: Re: [AFMUG] -48V kicking the dead horse




  On Jan 8, 2024, at 1:54 PM, Ken Hohhof  wrote:

  What I always have a hard time wrapping my head around is 240/120/208 wild 
leg delta.
   


I don’t think that one is hard to understand, other then the ‘why the hell did 
someone center tap a delta let anyway?Ok, I have designed systems that way 
but eventually somebody will blow something up with it given enough time.

(it’s useful when you need small quantities of single phase power in an 
otherwise 3 phase system)

Mark





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Re: [AFMUG] -48V kicking the dead horse

[Mark Radabaugh]

> On Jan 8, 2024, at 1:54 PM, Ken Hohhof  wrote:
> 
> What I always have a hard time wrapping my head around is 240/120/208 wild 
> leg delta.
>  

I don’t think that one is hard to understand, other then the ‘why the hell did 
someone center tap a delta let anyway?Ok, I have designed systems that way 
but eventually somebody will blow something up with it given enough time.

 (it’s useful when you need small quantities of single phase power in an 
otherwise 3 phase system)

Mark

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Re: [AFMUG] -48V kicking the dead horse

[Carl Peterson]

My rule for DC plants is BLACK == Ground Referenced side.


On Mon, Jan 8, 2024 at 11:02 AM Ken Hohhof  wrote:

> What I can never decide on is wire colors.  Especially when using red/black
> zipcord or tray cable.  People expect red to be +, but they also expect
> black to be ground (except electricians who expect black to be hot and
> white
> to be neutral and green or green/yellow to be ground).  And how to
> differentiate battery wiring from load wiring.  I have not found an ideal
> solution other than labels.
>
> -Original Message-
> From: AF  On Behalf Of Bill Prince
> Sent: Monday, January 8, 2024 10:45 AM
> To: af@af.afmug.com
> Subject: Re: [AFMUG] -48V kicking the dead horse
>
> Yes. -48VDC means the negative side is hot, and the positive side is ground
> (or return).
>
> You can mix +48VDC and -48VDC if you know what you're doing. It helps a
> bunch if the equipment floats logic ground. You need to check to see if
> your
> equipment isolates logic from the supply voltage.
>
> Yes. Batteries can be grounded either way. They don't care.
>
> bp
> 
>
> On 1/8/2024 8:25 AM, Mark - Myakka Technologies wrote:
> > I know we have been though this many times and I thought I understood it.
> >
> > -48VDC is the Negative side being HOT, correct?
> >
> > It is BAD to try to mix -48VDC and 48VDC
> >
> > There is no such thing as a -48V battery.  A battery is a battery,
> correct?
> >
> > How about the ICT Platinum power supplies.  They show as 48VDC, can they
> be used on -48VDC equipment?
> >
> > I remember Check saying something about a way to test to see if a piece
> of
> equipment that is Neg 48VDC is truly grounded as Neg 48VDC.
> >
> >
> > --
> >
> > Thanks,
> >   Mark  mailto:m...@mailmt.com
> >
> > Myakka Communications
> > www.Myakka.com
> >
> >
>
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Re: [AFMUG] -48V kicking the dead horse

[Chuck McCown via AF]

Have to have a chalk board to show the wild leg thing.  I got my 3 phase down 
pretty cold now.  

Had an electrician wire up a receptacle to the wild leg once.  
Blew up a transformer.  That was my first exposure to a wild leg.   



From: Ken Hohhof 
Sent: Monday, January 8, 2024 11:54 AM
To: 'AnimalFarm Microwave Users Group' 
Subject: Re: [AFMUG] -48V kicking the dead horse

I would think many of us have both 24V and 48V in the same rack or cabinet.  We 
started out 24V, then mixed, now able to do most sites all 48V, but lots of 
mixed 24 and 48 out there.  I think of -48 as just another voltage to keep 
straight.  If I power a radio or router with 48-56 volts that is intended for 
24-30V, bad things will happen.  Not sure what there is about polarity that 
drives people crazy.

 

What I always have a hard time wrapping my head around is 240/120/208 wild leg 
delta.

 

From: AF  On Behalf Of castarritt
Sent: Monday, January 8, 2024 12:35 PM
To: AnimalFarm Microwave Users Group 
Subject: Re: [AFMUG] -48V kicking the dead horse

 

The ICT shelves come in both +48v and -48v flavors.  Usually the positive 
version has a P on the end of the model.  An ICT-2U4 would be negative, and an 
ICT-2U4P is positive.  You can mix both -48 and +48 loads at one site, but you 
need an isolated DC-DC converter such as a Meanwell RSD-500C-48.

 

On Mon, Jan 8, 2024 at 10:26 AM Mark - Myakka Technologies  
wrote:

  I know we have been though this many times and I thought I understood it.

  -48VDC is the Negative side being HOT, correct?

  It is BAD to try to mix -48VDC and 48VDC 

  There is no such thing as a -48V battery.  A battery is a battery, correct?

  How about the ICT Platinum power supplies.  They show as 48VDC, can they be 
used on -48VDC equipment?

  I remember Check saying something about a way to test to see if a piece of 
equipment that is Neg 48VDC is truly grounded as Neg 48VDC.


  --

  Thanks,
  Mark  mailto:m...@mailmt.com

  Myakka Communications
  www.Myakka.com


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Re: [AFMUG] -48V kicking the dead horse

[Ken Hohhof]

I would think many of us have both 24V and 48V in the same rack or cabinet.  We 
started out 24V, then mixed, now able to do most sites all 48V, but lots of 
mixed 24 and 48 out there.  I think of -48 as just another voltage to keep 
straight.  If I power a radio or router with 48-56 volts that is intended for 
24-30V, bad things will happen.  Not sure what there is about polarity that 
drives people crazy.

 

What I always have a hard time wrapping my head around is 240/120/208 wild leg 
delta.

 

From: AF  On Behalf Of castarritt
Sent: Monday, January 8, 2024 12:35 PM
To: AnimalFarm Microwave Users Group 
Subject: Re: [AFMUG] -48V kicking the dead horse

 

The ICT shelves come in both +48v and -48v flavors.  Usually the positive 
version has a P on the end of the model.  An ICT-2U4 would be negative, and an 
ICT-2U4P is positive.  You can mix both -48 and +48 loads at one site, but you 
need an isolated DC-DC converter such as a Meanwell RSD-500C-48.

 

On Mon, Jan 8, 2024 at 10:26 AM Mark - Myakka Technologies mailto:m...@mailmt.com> > wrote:

I know we have been though this many times and I thought I understood it.

-48VDC is the Negative side being HOT, correct?

It is BAD to try to mix -48VDC and 48VDC 

There is no such thing as a -48V battery.  A battery is a battery, correct?

How about the ICT Platinum power supplies.  They show as 48VDC, can they be 
used on -48VDC equipment?

I remember Check saying something about a way to test to see if a piece of 
equipment that is Neg 48VDC is truly grounded as Neg 48VDC.


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 Mark  mailto:m...@mailmt.com  

Myakka Communications
www.Myakka.com  


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Re: [AFMUG] -48V kicking the dead horse

[castarritt]

The ICT shelves come in both +48v and -48v flavors.  Usually the positive
version has a P on the end of the model.  An ICT-2U4 would be negative, and
an ICT-2U4P is positive.  You can mix both -48 and +48 loads at one site,
but you need an isolated DC-DC converter such as a Meanwell RSD-500C-48.

On Mon, Jan 8, 2024 at 10:26 AM Mark - Myakka Technologies 
wrote:

> I know we have been though this many times and I thought I understood it.
>
> -48VDC is the Negative side being HOT, correct?
>
> It is BAD to try to mix -48VDC and 48VDC
>
> There is no such thing as a -48V battery.  A battery is a battery, correct?
>
> How about the ICT Platinum power supplies.  They show as 48VDC, can they
> be used on -48VDC equipment?
>
> I remember Check saying something about a way to test to see if a piece of
> equipment that is Neg 48VDC is truly grounded as Neg 48VDC.
>
>
> --
>
> Thanks,
>  Mark  mailto:m...@mailmt.com
>
> Myakka Communications
> www.Myakka.com
>
>
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Re: [AFMUG] -48V kicking the dead horse

[dmmoffett]

The issue is if the power supply or any of the equipment connected to it has
positive tied to ground and then you take another device with negative tied
to ground and put that on the same power supply.  Then you have + and - of
the power supply dead shorted through the ground connections and that's when
the sparks fly.  Some people keep the -48V stuff in a separate rack.  That's
not necessary, but it's not a bad safety measure if you have happen to have
enough space for two racks.  It's nice to say 

If the equipment has - tied to ground or tied to the chassis then it has to
be isolated from your -48V power supply.  You can still put it in the same
rack as everything else, but it needs a separate power supply isolated from
your -48V power system.  So you get an isolated 48V to 48V power supply
(Meanwell RSD-300C-48 is one example), or you plug that one device into an
A/C outlet or inverter or what have you.  I have test ONT's with -ground
sitting in the rack with with a bunch of -48V (+ground) routers and it's all
fine because they have their little DC transformers plugged into a wall
outlet. 

Someone said this, but to check if the equipment has a ground reference set
your multimeter for ohms and measure from each power input to the ground lug
and/or chassis of the device.  If you're reading an open circuit then you're
fine.  You're probably fine if you're reading a very large number of ohms
--I'd hate to give a specific number and say that's always safe, but the
Meanwell RSD I mentioned above is 100M Ohms from Input to Output per the
datasheet and that device has not failed me.  If you're seeing 0 or single
digits from one of the power leads to ground then you have power bonded to
ground on that device.  An example fresh in my mind is Mikrotik CRS305 has -
tied to ground, so although it will run on 48V I could not put it on our
-48V rectifier.  Lots of equipment intended for telecom will have +
connected to ground.  Also lots of equipment will have neither tied to
ground and those often work with either +V or -V (but I'd go by what the
manufacturer says first, and by the multimeter second).

-Adam



-Original Message-
From: AF  On Behalf Of Mark - Myakka Technologies
Sent: Monday, January 08, 2024 11:26 AM
To: af@af.afmug.com
Subject: [AFMUG] -48V kicking the dead horse

I know we have been though this many times and I thought I understood it.

-48VDC is the Negative side being HOT, correct?

It is BAD to try to mix -48VDC and 48VDC 

There is no such thing as a -48V battery.  A battery is a battery, correct?

How about the ICT Platinum power supplies.  They show as 48VDC, can they be
used on -48VDC equipment?

I remember Check saying something about a way to test to see if a piece of
equipment that is Neg 48VDC is truly grounded as Neg 48VDC.


--

Thanks,
 Mark  mailto:m...@mailmt.com

Myakka Communications
www.Myakka.com


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Re: [AFMUG] -48V kicking the dead horse

[Chuck McCown via AF]

I would be more than happy with that scheme.
Look up at a fuse or CB panel, see red and blue and you immediately know 
what you are working with.


-Original Message- 
From: dmmoff...@gmail.com

Sent: Monday, January 8, 2024 10:39 AM
To: 'AnimalFarm Microwave Users Group'
Subject: Re: [AFMUG] -48V kicking the dead horse

I concur with the wire color problem.

* My current employer pays big bucks to a low voltage guy who wires up our
sites.  His work is absolutely beautiful.  It's like friggin artwork.
He uses black for return (+) and green for ground.  Then since most of our
equipment has dual power supplies he uses red and blue for the "A" hot and
"B" hot.  I assume his employer trained him that way for a reason and that's
probably common.

* I was taught in childhood that red is positive, so that's what I have
always done.  I'm not philosophically opposed to the idea that red is "hot",
but that's just now how I learned it.

* https://ztlabels.com/blogs/news/dc-power-circuit-wiring-color-codes
This site advises that for 2-wire DC with positive ground is white for
positive and black for negative.  Someone apparently thinks that's the right
way.  The same site points out that the only color called out specifically
in the NEC is green or green/yellow for ground.  Everything else is just the
convention people landed on.

Out in the wild you might see anything so there is and will always be a
multi-meter in my everyday toolkit.

-Adam



-Original Message-
From: AF  On Behalf Of Ken Hohhof
Sent: Monday, January 08, 2024 12:01 PM
To: 'AnimalFarm Microwave Users Group' 
Subject: Re: [AFMUG] -48V kicking the dead horse

What I can never decide on is wire colors.  Especially when using red/black
zipcord or tray cable.  People expect red to be +, but they also expect
black to be ground (except electricians who expect black to be hot and white
to be neutral and green or green/yellow to be ground).  And how to
differentiate battery wiring from load wiring.  I have not found an ideal
solution other than labels.

-Original Message-
From: AF  On Behalf Of Bill Prince
Sent: Monday, January 8, 2024 10:45 AM
To: af@af.afmug.com
Subject: Re: [AFMUG] -48V kicking the dead horse

Yes. -48VDC means the negative side is hot, and the positive side is ground
(or return).

You can mix +48VDC and -48VDC if you know what you're doing. It helps a
bunch if the equipment floats logic ground. You need to check to see if your
equipment isolates logic from the supply voltage.

Yes. Batteries can be grounded either way. They don't care.

bp


On 1/8/2024 8:25 AM, Mark - Myakka Technologies wrote:

I know we have been though this many times and I thought I understood it.

-48VDC is the Negative side being HOT, correct?

It is BAD to try to mix -48VDC and 48VDC

There is no such thing as a -48V battery.  A battery is a battery,

correct?


How about the ICT Platinum power supplies.  They show as 48VDC, can
they

be used on -48VDC equipment?


I remember Check saying something about a way to test to see if a
piece of

equipment that is Neg 48VDC is truly grounded as Neg 48VDC.



--

Thanks,
  Mark  mailto:m...@mailmt.com

Myakka Communications
www.Myakka.com




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Re: [AFMUG] -48V kicking the dead horse

[dmmoffett]

I concur with the wire color problem.  

* My current employer pays big bucks to a low voltage guy who wires up our
sites.  His work is absolutely beautiful.  It's like friggin artwork. 
He uses black for return (+) and green for ground.  Then since most of our
equipment has dual power supplies he uses red and blue for the "A" hot and
"B" hot.  I assume his employer trained him that way for a reason and that's
probably common.

* I was taught in childhood that red is positive, so that's what I have
always done.  I'm not philosophically opposed to the idea that red is "hot",
but that's just now how I learned it.

* https://ztlabels.com/blogs/news/dc-power-circuit-wiring-color-codes
This site advises that for 2-wire DC with positive ground is white for
positive and black for negative.  Someone apparently thinks that's the right
way.  The same site points out that the only color called out specifically
in the NEC is green or green/yellow for ground.  Everything else is just the
convention people landed on. 

Out in the wild you might see anything so there is and will always be a
multi-meter in my everyday toolkit.  

-Adam



-Original Message-
From: AF  On Behalf Of Ken Hohhof
Sent: Monday, January 08, 2024 12:01 PM
To: 'AnimalFarm Microwave Users Group' 
Subject: Re: [AFMUG] -48V kicking the dead horse

What I can never decide on is wire colors.  Especially when using red/black
zipcord or tray cable.  People expect red to be +, but they also expect
black to be ground (except electricians who expect black to be hot and white
to be neutral and green or green/yellow to be ground).  And how to
differentiate battery wiring from load wiring.  I have not found an ideal
solution other than labels.

-Original Message-
From: AF  On Behalf Of Bill Prince
Sent: Monday, January 8, 2024 10:45 AM
To: af@af.afmug.com
Subject: Re: [AFMUG] -48V kicking the dead horse

Yes. -48VDC means the negative side is hot, and the positive side is ground
(or return).

You can mix +48VDC and -48VDC if you know what you're doing. It helps a
bunch if the equipment floats logic ground. You need to check to see if your
equipment isolates logic from the supply voltage.

Yes. Batteries can be grounded either way. They don't care.

bp


On 1/8/2024 8:25 AM, Mark - Myakka Technologies wrote:
> I know we have been though this many times and I thought I understood it.
>
> -48VDC is the Negative side being HOT, correct?
>
> It is BAD to try to mix -48VDC and 48VDC
>
> There is no such thing as a -48V battery.  A battery is a battery,
correct?
>
> How about the ICT Platinum power supplies.  They show as 48VDC, can 
> they
be used on -48VDC equipment?
>
> I remember Check saying something about a way to test to see if a 
> piece of
equipment that is Neg 48VDC is truly grounded as Neg 48VDC.
>
>
> --
>
> Thanks,
>   Mark  mailto:m...@mailmt.com
>
> Myakka Communications
> www.Myakka.com
>
>

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Re: [AFMUG] -48V kicking the dead horse

[Chuck McCown via AF]

I literally smoked a digital COE switch due to this one time.

I have seen Blue for hot and Red for return -48
I have seen Blue for hot and Black for return -48

Black for hot and Red for return in a -48 system.
Which would make that one Red+ and Black -  but positive ground.

Red for hot and Black for a return in many + and - systems.

So red is + in some systems and - in others.

I think I prefer red and black with red being positive and then you have to 
have enough brains to know that it is also return and usually ground with 
black being hot.  Should not be a stretch due to residential 120 VAC has 
black being hot.


So there, all confusion has now been erased... right...


-Original Message- 
From: Ken Hohhof

Sent: Monday, January 8, 2024 10:00 AM
To: 'AnimalFarm Microwave Users Group'
Subject: Re: [AFMUG] -48V kicking the dead horse

What I can never decide on is wire colors.  Especially when using red/black
zipcord or tray cable.  People expect red to be +, but they also expect
black to be ground (except electricians who expect black to be hot and white
to be neutral and green or green/yellow to be ground).  And how to
differentiate battery wiring from load wiring.  I have not found an ideal
solution other than labels.

-Original Message-
From: AF  On Behalf Of Bill Prince
Sent: Monday, January 8, 2024 10:45 AM
To: af@af.afmug.com
Subject: Re: [AFMUG] -48V kicking the dead horse

Yes. -48VDC means the negative side is hot, and the positive side is ground
(or return).

You can mix +48VDC and -48VDC if you know what you're doing. It helps a
bunch if the equipment floats logic ground. You need to check to see if your
equipment isolates logic from the supply voltage.

Yes. Batteries can be grounded either way. They don't care.

bp


On 1/8/2024 8:25 AM, Mark - Myakka Technologies wrote:

I know we have been though this many times and I thought I understood it.

-48VDC is the Negative side being HOT, correct?

It is BAD to try to mix -48VDC and 48VDC

There is no such thing as a -48V battery.  A battery is a battery,

correct?


How about the ICT Platinum power supplies.  They show as 48VDC, can they

be used on -48VDC equipment?


I remember Check saying something about a way to test to see if a piece of

equipment that is Neg 48VDC is truly grounded as Neg 48VDC.



--

Thanks,
  Mark  mailto:m...@mailmt.com

Myakka Communications
www.Myakka.com




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Re: [AFMUG] -48V kicking the dead horse

[Ken Hohhof]

What I can never decide on is wire colors.  Especially when using red/black
zipcord or tray cable.  People expect red to be +, but they also expect
black to be ground (except electricians who expect black to be hot and white
to be neutral and green or green/yellow to be ground).  And how to
differentiate battery wiring from load wiring.  I have not found an ideal
solution other than labels.

-Original Message-
From: AF  On Behalf Of Bill Prince
Sent: Monday, January 8, 2024 10:45 AM
To: af@af.afmug.com
Subject: Re: [AFMUG] -48V kicking the dead horse

Yes. -48VDC means the negative side is hot, and the positive side is ground
(or return).

You can mix +48VDC and -48VDC if you know what you're doing. It helps a
bunch if the equipment floats logic ground. You need to check to see if your
equipment isolates logic from the supply voltage.

Yes. Batteries can be grounded either way. They don't care.

bp


On 1/8/2024 8:25 AM, Mark - Myakka Technologies wrote:
> I know we have been though this many times and I thought I understood it.
>
> -48VDC is the Negative side being HOT, correct?
>
> It is BAD to try to mix -48VDC and 48VDC
>
> There is no such thing as a -48V battery.  A battery is a battery,
correct?
>
> How about the ICT Platinum power supplies.  They show as 48VDC, can they
be used on -48VDC equipment?
>
> I remember Check saying something about a way to test to see if a piece of
equipment that is Neg 48VDC is truly grounded as Neg 48VDC.
>
>
> --
>
> Thanks,
>   Mark  mailto:m...@mailmt.com
>
> Myakka Communications
> www.Myakka.com
>
>

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Re: [AFMUG] -48V kicking the dead horse

[Chuck McCown via AF]

I mixed + and - 48 in a off grid solar system.  I had one battery bank with 
the positive to the common point/ ground.  The other battery bank was 
negative to the common point.  From one battery to the other it was 96 volts 
when went to the load.


But I had two 48 volt solar systems and charge controllers and they charged 
each half of the total battery independently.  One of the charge controllers 
had to be mounted on an insulating board because its chassis was hot.


The whole -48, +48 thing is all about what is connected to the ground, 
common point, return etc.  If you ground the negative side of a battery you 
have a positive voltage hot wire system.  If you ground the positive side of 
a battery you have a negative voltage hot wire.  The battery itself does not 
care.


If you load does not have an electrical connection to a grounded chassis, it 
will not car either.


However if you have a device that is designed to be powered from -48 and 
internally its positive 48 connections are all bonded to its metallic 
chassis, it really needs to be powered from a floating supply or a -48 
supply.


There is no good reason to ground either side of a DC supply in a system 
these days.  Originally telcos went with positive grounding so that if you 
had an insulation fault in an underground cable, the -48 volt ring side (hot 
side) of the phone line would tend to attract metallic ions from the 
surrounding soil.  If it was reversed the wire would donate copper ions to 
the soil and quickly plate itself away to nothingness.





-Original Message- 
From: Mark - Myakka Technologies

Sent: Monday, January 8, 2024 9:25 AM
To: af@af.afmug.com
Subject: [AFMUG] -48V kicking the dead horse

I know we have been though this many times and I thought I understood it.

-48VDC is the Negative side being HOT, correct?

It is BAD to try to mix -48VDC and 48VDC

There is no such thing as a -48V battery.  A battery is a battery, correct?

How about the ICT Platinum power supplies.  They show as 48VDC, can they be 
used on -48VDC equipment?


I remember Check saying something about a way to test to see if a piece of 
equipment that is Neg 48VDC is truly grounded as Neg 48VDC.



--

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Mark  mailto:m...@mailmt.com

Myakka Communications
www.Myakka.com


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Re: [AFMUG] -48V kicking the dead horse

[Bill Prince]

Yes. -48VDC means the negative side is hot, and the positive side is 
ground (or return).


You can mix +48VDC and -48VDC if you know what you're doing. It helps a 
bunch if the equipment floats logic ground. You need to check to see if 
your equipment isolates logic from the supply voltage.


Yes. Batteries can be grounded either way. They don't care.

bp


On 1/8/2024 8:25 AM, Mark - Myakka Technologies wrote:

I know we have been though this many times and I thought I understood it.

-48VDC is the Negative side being HOT, correct?

It is BAD to try to mix -48VDC and 48VDC

There is no such thing as a -48V battery.  A battery is a battery, correct?

How about the ICT Platinum power supplies.  They show as 48VDC, can they be 
used on -48VDC equipment?

I remember Check saying something about a way to test to see if a piece of 
equipment that is Neg 48VDC is truly grounded as Neg 48VDC.


--

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  Mark  mailto:m...@mailmt.com

Myakka Communications
www.Myakka.com




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Re: [AFMUG] -48V kicking the dead horse

[Ken Hohhof]

Most AC/DC and DC/DC power supplies have input/output isolation and neither
side of the output grounded unless/until you ground one side.  If you ground
the - side, then it's referred to as +48V.  If you ground the + side, then
it's -48V.

Fancier equipment with stuff like management interfaces may be dedicated as
+48V or -48V, I have an Eltek Micropack system that can only be used as
-48V.  Lots of stuff from the telecom world may be that way.  Something like
a Mean Well power supply will almost certainly be floating until you ground
one side of the output.

I know a WISP guy who tends to power all his DC+fiber radios with individual
AC/DC power supplies and doesn't ground them.  I am a traditionalist and
want all my power supplies ground referenced, but it seems to work for him.
I guess you could argue it prevents ground loops.

Where we typically run into problems is with the loads like radios and
routers, sometimes they are floating and don't care, some have the + side
grounded, some have the - side grounded.  Chuck was probably saying to check
with an ohmmeter from DC+ and DC- to chassis ground.  I have also been lucky
that when I got it wrong, it just popped a fuse and no magic smoke escaped.
Hopefully you individually fuse all your loads.



-Original Message-
From: AF  On Behalf Of Mark - Myakka Technologies
Sent: Monday, January 8, 2024 10:26 AM
To: af@af.afmug.com
Subject: [AFMUG] -48V kicking the dead horse

I know we have been though this many times and I thought I understood it.

-48VDC is the Negative side being HOT, correct?

It is BAD to try to mix -48VDC and 48VDC 

There is no such thing as a -48V battery.  A battery is a battery, correct?

How about the ICT Platinum power supplies.  They show as 48VDC, can they be
used on -48VDC equipment?

I remember Check saying something about a way to test to see if a piece of
equipment that is Neg 48VDC is truly grounded as Neg 48VDC.


--

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 Mark  mailto:m...@mailmt.com

Myakka Communications
www.Myakka.com


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Re: [AFMUG] -48V kicking the dead horse

[Josh Luthman]

>It is BAD to try to mix -48VDC and 48VDC

Very

>There is no such thing as a -48V battery.  A battery is a battery, correct?

Correct.  You still wire + to + and - to -

>How about the ICT Platinum power supplies.  They show as 48VDC, can they
be used on -48VDC equipment?

Pretty confident, this is their industry.  Cliff is my contact who can
confirm.

On Mon, Jan 8, 2024 at 11:27 AM Mark - Myakka Technologies 
wrote:

> I know we have been though this many times and I thought I understood it.
>
> -48VDC is the Negative side being HOT, correct?
>
> It is BAD to try to mix -48VDC and 48VDC
>
> There is no such thing as a -48V battery.  A battery is a battery, correct?
>
> How about the ICT Platinum power supplies.  They show as 48VDC, can they
> be used on -48VDC equipment?
>
> I remember Check saying something about a way to test to see if a piece of
> equipment that is Neg 48VDC is truly grounded as Neg 48VDC.
>
>
> --
>
> Thanks,
>  Mark  mailto:m...@mailmt.com
>
> Myakka Communications
> www.Myakka.com
>
>
> --
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> AF@af.afmug.com
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>
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[AFMUG] -48V kicking the dead horse

[Mark - Myakka Technologies]

I know we have been though this many times and I thought I understood it.

-48VDC is the Negative side being HOT, correct?

It is BAD to try to mix -48VDC and 48VDC 

There is no such thing as a -48V battery.  A battery is a battery, correct?

How about the ICT Platinum power supplies.  They show as 48VDC, can they be 
used on -48VDC equipment?

I remember Check saying something about a way to test to see if a piece of 
equipment that is Neg 48VDC is truly grounded as Neg 48VDC.


--

Thanks,
 Mark  mailto:m...@mailmt.com

Myakka Communications
www.Myakka.com


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