Electrical standards for control cabinets

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freecrowder

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What does the standards say about Hoffman style control cabinets that are interlocked with incoming power. In particular can you mount sub-circuits operating at 480vac on the inside door panel. If the door were opened and the safety interlock to incoming power were bypassed then the 480vac would be exposed on the inside of the swung opened door. Now this is taking into consideration that under those conditions an authorized tech is doing any troubleshooting or maintenance style work.
 
What standards,(this is an NEC topic)?
The NEC is an installation standard not a safety standard. If you bypass an interlock then that person should be qualified.
So perhaps the question should be what do your plant standards require if you bypass the safety interlock?
 
There is a good chance that an OSHA inspector (if for any reason they get involved, like after the fact) will say that the presence of exposed live terminals inside the cabinet when the bypass is engaged would make the whole operation hot work and subject to all of the restrictions (mostly summarized as "Don't!") associated with hot work.

But, as Tom stated, this is a matter for the company safety policy, not the NEC.
 
I don't believe this would be a violation of the NEC 409 which covers control panels. I don't know UL508A enough to say if it is ok with hanging line voltage parts on the door.
If it was me I'd just buy another cabinet or a bigger one if it's a new build. I do hang drives and terminals both line and control voltage on the sides of cabinets. And of
course switches and lights, estops etc mount on the doors. But I have never seen any contactors, drives etc mounted on a door. But a sure bet it's been done, although I wouldn't
do it myself.
 
Aleman said:
I don't believe this would be a violation of the NEC 409 which covers control panels. I don't know UL508A enough to say if it is ok with hanging line voltage parts on the door.
If it was me I'd just buy another cabinet or a bigger one if it's a new build. I do hang drives and terminals both line and control voltage on the sides of cabinets. And of
course switches and lights, estops etc mount on the doors. But I have never seen any contactors, drives etc mounted on a door. But a sure bet it's been done, although I wouldn't
do it myself.
Click to expand...

UL508a allows you to hang anything on the back of the door you want to, as long as the door supports it. No panel is required either. If you have something with a voltage that exceeds some low level (maybe 30 Volts??) a bonding conductor to the door is required.
 
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