Art 725 and how it relates to other articles.

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Robert Beeson

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Denver, CO. USA
Good day,

I have an inspector in the Denver Colorado area who insists that all of my class 1, 2, and 3 circuits (50 volt and less) as described in article 725 must adhere to article 200.6 and therefore all grounded 24 volt systems negative or common conductors must have a continuous white or gray outer finish or a white or gray stripe.

This is not consistent with the industry standards or the control drawings that were provided me for installation.

I interpret Art. 725.3 "Other Articles" to say that only Art. 300 applies to Class 1, 2 and 3 circuits.

Can someone shed some light on this for me?

I greatly appreciate your time.

Kind Regards
 
Why are the <50v circuits grounded ? {Ref 250.20(A)}|
I may be overlooking something but I don't see where Art 725 exempts Art 200, as it does Art 300 (with exceptions), but I don't see the need for grounding circuits less than 50v unless required in 250.20.
 
Art 725 and how it relates to other articles

Art 725 and how it relates to other articles

The power supplies provided came with instructions to ground them at a specific location. These instructions did not specify a conductor color for use. The plans we were given from the controls contractor for installation are typical of plans we have been using repeatedly and do call out for a black conductor on the negative or common terminal and a white conductor on the positive or hot terminal. The inspector says that if the power supply (24V) is grounded the white cannot be a positive or hot and the negative or common must be white or gray.

I have never seen this apply to 24 volt controls.
 
725.3 is specific to (A) through (L) with only specifically referenced sectons of ART 300 as you have stated. That does not mean other articles are not applicable. It refers to the fact that not all of ART 300 is applicable. 90.3 should clear up which sections are applicable - Augie 47 statement is well put as not all 725 type circuits fall under the requirements of 250.20(A).
 
Art 725 and how it relates to other articles

Art 725 and how it relates to other articles

Thank you for the response. is it your opinion that according to the NEC, "24 volt control wiring as it relates to 725 (Class 1, 2, 3) must be installed according to 200.6"

Does anyone else have an opinion?

Thanks to all.
 
Robert Beeson said:
Thank you for the response. is it your opinion that according to the NEC, "24 volt control wiring as it relates to 725 (Class 1, 2, 3) must be installed according to 200.6"

Does anyone else have an opinion?

Thanks to all.
Click to expand...
As much as I would like to say "no", and perhaps, as requested, someone else may know a reason not to, but, if one conductor is grounded, it seems it must be so identified.
 
Robert Beeson said:
Thank you again, much appreciated.

Anyone else care to venture an opinion?

Cheers
Click to expand...
You can get away with not using a white or gray insulated conductor if you mark them with white or gray at the termination...

200.7 Use of Insulation of a White or Gray Color or
with Three Continuous White or Gray Stripes.

(A) General. The following shall be used only for the
grounded circuit conductor, unless otherwise permitted in
200.7(B) and (C):
(1) A conductor with continuous white or gray covering
(2) A conductor with three continuous white or gray stripes
on other than green insulation
(3) A marking of white or gray color at the termination

(B) Circuits of Less Than 50 Volts. A conductor with
white or gray color insulation or three continuous white
stripes or having a marking of white or gray at the termination
for circuits of less than 50 volts shall be required to
be grounded only as required by 250.20(A).

(C) Circuits of 50 Volts or More. ...
Click to expand...

... but as stated, you cannot use white insulation for an ungrounded conductor.
 
Robert Beeson said:
Thank you again, much appreciated.

Anyone else care to venture an opinion?

Cheers
Click to expand...

The scope of Article 200 applies to 'premises wiring systems'. The definition of Premises Wiring (System) clearly includes control and signalling.

I believe many 725 installations have been made using the exception for identifying grounded conductors in multi-conductor cables by 'other equally effective means'.
 
OK, how is this situation any different from a common furnace thermostat install? The preferred colors for fan control are green, and for heating to be white. Some thermostats have a common wire which is usually blue. I'm not sure if most HVAC installs have any grounding on the 24VAC side of the system, and perhaps that's the difference (would think if they use a common wire it would end up grounded). Otherwise the green and white colors seem to run afoul of the NEC 250/200 color conventions and have for eons.
 
The circuit may well be ungrounded and at less than 50v, 200.7(B) would only required it to be grounded if required by 250.20(A) and at being less than 50v the white would not be required to be re-identified sinc eit falls under 200.7(B) and not (C).
 
Robert,

The Code is pretty clear on this issue. Section 200.7(B) requires the white or gray conductor to be grounded only as required by 250.20(A). If you choose to ground a conductor of this system, it is required to be identified white or gray. There is nothing in Article 725 that modifies this requirement.
 
However, if the control wiring is a flexible cable with an attached connector it may be part of listed equipment rather than premises wiring, especially if it links two units from the same manufacturer. If it is hard wired, it is harder to make that argument.
 
RB1 said:
Robert,

The Code is pretty clear on this issue. Section 200.7(B) requires the white or gray conductor to be grounded only as required by 250.20(A). If you choose to ground a conductor of this system, it is required to be identified white or gray. There is nothing in Article 725 that modifies this requirement.
Click to expand...

Or "marked at termination" as noted by Smart$ in post #8
(I missed that in my research)
 
augie47 said:
Or "marked at termination" as noted by Smart$ in post #8
(I missed that in my research)
Click to expand...
Exactly.

You can use any combination of circuit conductor colors and mark the grounded conductor white (or gray) at terminations... but in no case can you use a white- or gray-insulated (or 3x white traced) conductor as an ungrounded conductor where the system is grounded.
 
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