"Supervised location"

[charlie b]

I was reviewing a set of plans and specs and an odd question came to my mind. I know how the NEC defines "supervised location," and I know there are instances in which the rules are less stringent in such locations. But how does a reviewer judge whether the designer inappropriately took advantage of such rules for a facility? In other words, do I need to verify that the facility has documented training that establishes the qualifications of their workers, or perhaps has documented maintenance procedures, or perhaps has documented processes for monitoring equipment status?

The issue of interest is a 12.5 kv to 480/277 v service transformer with the downstream breaker above 125% of the rated secondary current (but below 250%). That is allowed only in supervised locations, and I have nothing that tells me that the facility meets that description. Is it worth asking the designer to explain their basis for applying the 250% allowance?

 

[tom baker]

Yes ask then it’s in writing. And insert that response into the plans

 

[Elect117]

I typically reserve supervised locations for commercial manufacturing where safety plans exist (lock out, tag out, etc.) and maintenance staff are onsite during normal operations.

Anything short of that should be in a locked room or isolated area where it is inaccessible and the facility has a onsite maintenance program that requires them to contract with a company to perform maintenance and inspections.

Lastly, I have asked for companies to update their safety training to ensure certain procedures like lock out and tag out exist. They wanted to use 430.102(B) for motor disconnecting means in a meat processing plant where the assembly/conveyer system was built high off the ground and line of sight was not going to be achieved for a section of it due to a metal barrier for fall protection.

I have also had a hard time with section 702.5(A)'s exception. Even with a kirk key interlocking system, it is hard to ensure that the person calling for the generator or the person plugging in the generator is knowledgeable about the existing system's loading before plugging in the generator.

 

[shockking]

Just curious, what is the location exactly? and what kVA transformer?

 

[charlie b]

Just curious, what is the location exactly? and what kVA transformer?

2500 KVA. Military base. That should mean they have a maintenance department that would satisfy the "supervised location" requirements. But I know nothing about this base and can't assume anything about their maintenance personnel.

 

[letgomywago]

2500 KVA. Military base. That should mean they have a maintenance department that would satisfy the "supervised location" requirements. But I know nothing about this base and can't assume anything about their maintenance personnel.

If military I'd assume that it's supervised but not well. That probably doesn't help much but they don't live by osha.