DC conductor markings

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mbrooke

mbrooke

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Would 210.5 (c)(2)(a)(4) still apply to reversing polarity circuits? I see no exception, but how do you force compliance on an application where its technically not applicable? And I guess my question also applies to all of 210.5 (C) 2

 
If you ever ran train tracks, then to make the train back up you reversed the polarity. Some dc motors and other circuits do exactly the same thing..l reverse the polarity Togo backwards...
 
mbrooke said:
One where any two wires can be either pos or negative at any given time.
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Actually I had kind of guessed that part - really, I did. How about some context where this would be used?

Reason I'm asking, is:
I haven't seen one, but I suspect** the application is in controls, and possibly (probably) not be considered a "branch circuit".

**Means I don't know, I'm guessing - but interested.

ice
 
Adamjamma said:
If you ever ran train tracks, then to make the train back up you reversed the polarity. Some dc motors and other circuits do exactly the same thing..l reverse the polarity Togo backwards...
Click to expand...

Toy trains? If so that would be permanent magnet motors. And definitely not a branch circuit.
 
iceworm said:
Actually I had kind of guessed that part - really, I did. How about some context where this would be used?

Reason I'm asking, is:
I haven't seen one, but I suspect** the application is in controls, and possibly (probably) not be considered a "branch circuit".

**Means I don't know, I'm guessing - but interested.

ice
Click to expand...

DC motor reversal in equipment.
 
I think they can be anything you want besides green, white or grey.

FWIW, our model railroad club uses black and red even though the polarity is switched and the black is really a common return.
 
I'm stuck on this not being a "Branch Circuit" as defined in Article 100.

The branch circuit ended once the conductors from the last OCPD hit the outlet. I don't see NEC 210.5.C.2 applies. However, I am guessing there is a control panel, contactors, semiconductors, or even a DPDT switch. And all that is after the "outlet".

Suggest:
NEC 409
NFPA 79
UL 508A
 
iceworm said:
I'm stuck on this not being a "Branch Circuit" as defined in Article 100.

The branch circuit ended once the conductors from the last OCPD hit the outlet. I don't see NEC 210.5.C.2 applies. However, I am guessing there is a control panel, contactors, semiconductors, or even a DPDT switch. And all that is after the "outlet".

Suggest:
NEC 409
NFPA 79
UL 508A
Click to expand...

There is a contractor, yes.
 
From the final OCPD to the control circuit you have normal branch circuit wiring, and the polarity is not reversing. In which case the color code requirements are not a problem.

After the control system I think that iceworm's suggestion makes the most sense, that you no longer have 'branch circuit' wiring, so the color code requirement simply doesn't apply. Once you hit the control equipment you are in 'field wiring' of the apparatus.

A couple of other possible arguments:

After the control circuit (with its reversing contactor and what not) you no longer have _DC_. If it reverses polarity you have AC (maybe very very low frequency AC), so rules for DC don't apply. Of course you might then have problems with the _grounded conductor_ (white wire) being switched.

What happens if you have a large reversing _system_, eg. a set of 10 motors and you want to reverse all of them at the same time, so you have your reversing contactor feeding a panel, and then 10 separate branch circuits feeding 10 separate motros :) (Okay, this is just me being difficult....)

-Jon
 
mbrooke said:
There is a contractor, yes.
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Well, if you consider the controls an Industrial Control Panel, following NEC 409, then there is a wiring diagram. Consider just making the drawing cable tags match the physical cable tags. I'm thinking, Not an issue - good design, meets code.

ice
 
iceworm said:
Well, if you consider the controls an Industrial Control Panel, following NEC 409, then there is a wiring diagram. Consider just making the drawing cable tags match the physical cable tags. I'm thinking, Not an issue - good design, meets code.

ice
Click to expand...

Thank you for your input! :)
 
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