Identifying the grounded conductor in existing electrical systems

[jay boucher]

We are performing a lighting system upgrade to a very large commercial facility that presently incorporates 1000W metal halide fixtures with basically no controls. We will be replacing these fixtures with highly efficient LED fixtures with integral wireless controls. In the process we want to rewire these existing 480V single phase branch circuits to the lighting system to operate at 277V since the LED equipment does not come standard at 480V, and furthermore we will be significantly reducing the connected load on each branch circuit. It will be virtually cost prohibitive to rewire the branch circuits in order to get a gray wire as the identified grounded conductor on each circuit and the only practical solution is to identify the neutral conductor with gray phasing tape at each junction box, panel etc.
The code requires all new installations to install conductors that are clearly identified continuously along the entire length of the neutral conductor. however, since this is an existing system and the logistics of trying to pull in identified conductors for the neutral are cost prohibitive, i would assume that the code would allow for the alternate method of identifying these conductors through the use of phasing tape, as the overall lighting system will be significantly improved with the implementation of this new LED solution.

So i am looking to see if anyone else has run into this before and if so, what was the resolution.
Thanks,

 

[Dennis Alwon]

There is no way to know what your authority having jurisdiction may say. IMO, I see no issue with it in terms of dangers however it would not be compliant and I don't think the NEC would allow it. Sometimes you just have to use common sense which the code cannot do.

The NEC does give allowance to get permission from the authority having jurisdiction in situations like this.

 

[jay boucher]

Dennis,

Dennis,

thanks for the reply and i have to say that i completely concur with your observation. I was just hoping to get some feedback before approaching the AHJ........

 

[kwired]

Unfortunately NEC does not factor cost into it's requirements, if it did 90.1 would not really have much meaning. I will not say cost has never been somewhat involved in any requirements though.

AHJ kind of has the final say on your proposed methods, and remember AHJ is not always an electrical inspector, though often that is who we commonly relate to when the NEC mentions AHJ.

 

[jay boucher]

90.1

90.1

Great point about article 90.1! After all, the intent of the NEC - according to article 90. "is the practical safeguarding of persons ?and property from hazards arising from the use of electricity"!

In this particular instance the project is for a private institution that has its own electrical maintenance staff, electrical engineers on staff etc and they will be the ones maintaining this electrical system once the project has been completed. They have no problem with the changing of the voltage from 480 to 277 to each fixture- as a matter of fact they definitely want to make this change. So with that being said, I would like to think that common sense will prevail and the AHJ will allow us to change the voltage from 480 to 277, clearly identify the neutral conductor at all panels, termination points etc throughout the system and proceed with the project without completely rewiring the branch circuits.

 

[tom baker]

I would like to think that common sense will prevail and the AHJ will allow us to change the voltage from 480 to 277, clearly identify the neutral conductor at all panels, termination points etc throughout the system and proceed with the project without completely rewiring the branch circuits.

While the facility may have dedicated maintenance staff today, what about if it gets sold? Or closed and reopened? You may need to apply for special permission as this clearly violates the NEC.

 

[lakee911]

Whatever you do, make sure you get it in writing!

Can you use an xformer some place to derive a neutral? Can your special order 480V fixtures?

 

[jap]

Why would it be virtually cost prohibitive to pull out a Brown, Orange or Yellow and pull in a Gray with it?
Since your replacing existing 1000w HID Fixtures I'm assuming the Ceiling is very high and probably very hard to get to. Not sure.
How many fixtures and circuits are you up against ?

 

[qcroanoke]

Why would it be virtually cost prohibitive to pull out a Brown, Orange or Yellow and pull in a Gray with it?
Since your replacing existing 1000w HID Fixtures I'm assuming the Ceiling is very high and probably very hard to get to. Not sure.
How many fixtures and circuits are you up against ?

The need for another lift if the ceiling is high and a man on it.

 

[jap]

The need for another lift if the ceiling is high and a man on it.

If that's all, it'd be well worth doing it right then.