208 volt switch gear being used at 480 volt?

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mstephenson

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I have a situation where a competing electrical contractor for a fairly good sized job has informed a potential customer that he can re-use an existing 12 year old 3000 amp switch gear with a 208/120 volt name plate and UL listing at 480 volts. The switches in the gear are rated at 600 volt. I have talked with one of the gear manufactures engineers and he said that the buss was probably rated at 600 volt, but they would not put that on paper or guarantee it at 480 volts. My questions is, Am I wrong in saying that using this gear would be a violation of the NEC code as it is not UL listed for use at 480 volts?
 
IMHO, I do not believe that this installation would be acceptable and a violation of 110.3(B).

Not that it really matters in relation to my opinion but is this gear equipped with a single main? If so is there GFP present?

Pete
 
mstephenson said:
I have a situation where a competing electrical contractor for a fairly good sized job has informed a potential customer that he can re-use an existing 12 year old 3000 amp switch gear with a 208/120 volt name plate and UL listing at 480 volts. The switches in the gear are rated at 600 volt. I have talked with one of the gear manufactures engineers and he said that the buss was probably rated at 600 volt, but they would not put that on paper or guarantee it at 480 volts. My questions is, Am I wrong in saying that using this gear would be a violation of the NEC code as it is not UL listed for use at 480 volts?
Click to expand...

The reality is that there is usually no difference between this kind of switch gear that has a 480V nameplate and one that has a 208V nameplate other than the nameplate.

I can understand why the manufacturer is unwilling to send them a new nameplate when not doing so will encourage the end user to buy new gear.

I am not sure that what the nameplate says is part of the listing. You might want to look closely at what the listing from UL actually says. It may be that the nameplate is informative of the expected end use rather than a limitation on the use of the gear.

As a practical matter, it is almost certain that the actual rating of the bus is on paper somewhere. The manufacturer's engineer may be playing a bit coy with you on this one.

OTOH, I could understand an inspector having a cow about it.

I vote for a field evaluation as well.

One thing that might be an issue is the voltage rating of whatever overcurrent devices exist. If it was originally 208V, they might have used devices not rated for 480V.
 
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The equipment rating is whatever it is. The nameplate is field-installed as information about the installation. As long as all components are adequately rated, and the nameplate is changed to reflect the new voltage, I don't see the problem.
 
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I had a manufactures field rep take a look at the gear. He sent the information he got off the gear to the manufactures factory where the gear was originally manufactured. They responded that the buss would have to be replaced with buss rated at 480 volts. Also, the AIC rating on the existing 208 volt gear would not be correct for the change. The building has two utility transformers, one feeding 208/120 power supply and another feeding the 480/277 power supply. However, I appreciate the
responses.
 
mstephenson said:
I had a manufactures field rep take a look at the gear. He sent the information he got off the gear to the manufactures factory where the gear was originally manufactured. They responded that the buss would have to be replaced with buss rated at 480 volts. Also, the AIC rating on the existing 208 volt gear would not be correct for the change. The building has two utility transformers, one feeding 208/120 power supply and another feeding the 480/277 power supply. However, I appreciate the
responses.
Click to expand...

Thanks for the update. If the buss is to be replaced I would also ask if the current listing for the equipment will remain valid. Just a suggestion.

Pete
 
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