Jodi

I'm on a job where the home runs are being pulled with 12-4 MC. It's a commercial building with 3 phase system. They are pulling two circuits in each 12-4 cable and taping the blue to white on the receptacle circuits and taping the yellow to white on the 277v lighting. Is this permitted and are there effects on the circuits if its not.

Dennis Alwon

I would say NO since the color code on the phase conductors cannot be the same. I have never seen anyone tape a wire while in a multiconductor cable but perhaps it is okay since I don't see 12/2/2 MC marketed.

I guess you could also tape the 277 system hot conductors also. Sounds like a bad install as they make MC with a different phasing color code

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mcclary's electrical

Where do these circuits originate? How do you have 120 and 277 in the same panel? Two systems both using white as a neutral does not seem compliant to me. But it sounds like if you tape it grey, it's ok:

(D) Grounded Conductors of Different Systems.

Where
grounded conductors of different systems are installed in
the same raceway, cable, box, auxiliary gutter, or other type
of enclosure, each grounded conductor shall be identified
by system. Identification that distinguishes each system
grounded conductor shall be permitted by one of the following
means:
(1) One system grounded conductor shall have an outer
covering conforming to 200.6(A) or (B).
(2) The grounded conductor(s) of other systems shall have
a different outer covering conforming to 200.6(A) or
200.6(B) or by an outer covering of white or gray with
a readily distinguishable colored stripe other than green

running along the insulation.

200.6 Means of Identifying Grounded Conductors.
(A) Sizes 6 AWG or Smaller.

An insulated grounded conductor
of 6 AWG or smaller shall be identified by a continuous
white or gray outer finish or by three continuous
white stripes on other than green insulation along its entire
length. Wires that have their outer covering finished to
show a white or gray color but have colored tracer threads
in the braid identifying the source of manufacture shall be
considered as meeting the provisions of this section. Insulated
grounded conductors shall also be permitted to be
identified as follows:
(1) The grounded conductor of a mineral-insulated, metalsheathed
cable shall be identified at the time of installation
by distinctive marking at its terminations.
(2) A single-conductor, sunlight-resistant, outdoor-rated
cable used as a grounded conductor in photovoltaic
power systems as permitted by 690.31 shall be identified
at the time of installation by distinctive white
marking at all terminations.
(3) Fixture wire shall comply with the requirements for
grounded conductor identification as specified in 402.8.
(4) For aerial cable, the identification shall be as above, or
by means of a ridge located on the exterior of the cable
so as to identify it.

(B) Sizes Larger Than 6 AWG.

An insulated grounded
conductor larger than 6 AWG shall be identified by one of
the following means:
(1) By a continuous white or gray outer finish.
(2) By three continuous white stripes along its entire length
on other than green insulation.
(3) At the time of installation, by a distinctive white or
gray marking at its terminations. This marking shall

encircle the conductor or insulation.

Jlarson

You can get neutral per phase cable that gives you black, red, white/black traced, and white/red traced.

You can get the same deal in traditional 277/480 colors with traced grey neutrals too.

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jrannis

Yeah, somebody screwed up. I think you can get what ever colors you want is you purchase enough but just for safe practice, I would buy and install a separate cable for a home run. If you had 1000 home runs and they averaged 100' each, I could see some motivation to try this but, if your AHJ doesn't like it of changes his mind, you will be buying it anyway.

__________________
"When a your only tool is a hammer, every problem looks like a nail"

Shockdoc

It will make it easy latter on in life to "steal" a circuit by changing the blue back to a hot.

__________________
All these liberal laws has turned me into a right wingnut..

Dennis Alwon

I looked at Southwire and did not see that in MC. I know it is available with NM. The whole setup seems inappropriate, IMO.

The question remains whether it can be done and be compliant.

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Dennis Alwon

The other question that comes to mind is why they are not using 3 hots with one neutral since it is 3 phase. I must assume that there is a legitimate reason as some jobs spec individual neutrals.

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Jlarson

The stuff we get is AFC cable.


I don't see why the taping would be a problem. I think Mcclary pointed out the only problem they might run into.

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The best never stop learning.

NJELEC

here is the AFC cable some local supply house's are now carrying.

http://www.afcweb.com/pdf_2011/p24_mc_p.pdf

Magnettica

Seems like shenanigans to me..

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Jodi

Thanks for comments. I made a mistake in original post. The 277v yellow is taped grey not white. The job spec was for each circuit to have a designated neutral on both lighting and power. Two systems, two different panels (MC landing in 2 troughs for splicing before panels) They could have used the cable recommended by Magnettica from AFC called MC-Plus Neutral per Phase Cable. I was wondering wether the twist in the cable was the same in regular 12/4 as opposed to the cable with the designated neutrals. Do they twist the pairs together in the neutral designated cable? Can the voltage in one pair effect the other. Must the circuits be on separate phases if they are not sharing a neutral. Will heat be created in the aluminum or steel jacket? I'll call AFC tomorrow and ask if the 12/4 MC is made the same as 12/4 MC Plus. I didn't see anything in the tech specs from AFC.