480 volt maintenance

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Daniel Stack

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NJ
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Electrical contractor
I am involved in a 250 bed temp hospital and installed temporary cable feeding 480 volt system. I thought it requires 2 men to maintain 480 volt temp but cant for the life of me find any documentation about it. I being told only one man to maintain. I don’t think that’s safe if something goes wrong and needs to be worked on. Any info would help.
 
What do you mean by maintain, are you referencing working on it while energized?

Welcome to the Forum. :)
 
OSHA requires two people minimum if working on anything over 600V when exposed to live conductors or devices. So maybe that's what you are remembering.

29 CFR 1910.269(1)(1)(i)
 
Daniel Stack said:
Yes
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I'm more than a little surprised that you are permitted to work on it live. Admittedly, I was in a different field - industrial where you had to have all the PPE, lock off, tag off, and all the approved documentation in place before you were allowed near any piece of kit.
 
Daniel Stack said:
Nothing for 480 volt? Hard to believe. Thank you
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Many companies have a work rule like this so you commonly run into it, but it is not code.
My company rules require two individuals, but the second one does not need to be NFPA70E qualified, they simply need to be able to contact emergency responders.
 
Besoeker3 said:
I'm more than a little surprised that you are permitted to work on it live. Admittedly, I was in a different field - industrial where you had to have all the PPE, lock off, tag off, and all the approved documentation in place before you were allowed near any piece of kit.
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Electrical lockout IS energized work. You have to test live conductors to verify absence of voltage. Until that point it is considered potentially energized. That’s part of OSHA Subcgapter S for electrical (not general) lockouts. So is grounding for obvious reasons. Breaker and disconnect contacts occasionally weld together far more often than you would expect and some switchgear breakers have to be racked off the bus for lockout where you literally put the lock through the track to prevent racking it back in.
 
Jraef said:
OSHA requires two people minimum if working on anything over 600V when exposed to live conductors or devices. So maybe that's what you are remembering.

29 CFR 1910.269(1)(1)(i)
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You just jumped from utilization rules (Subchapter S) to transmission/distribution rules 1910.269 which may not apply here. Plus you missed the three exceptions that for all intents and purposes all but nullify it. Exceptions where the rule would apply would be things like replacing insulators where a lineman installs an insulator then removed the lashing and physically hoists the cable up then sets it back down on the new insulator while it is energized. The rule essentially requires a ground man. Except for emergency work.

The 70E rule is indirect. It is sort of buried in the training section discussing CPR. It is potentially possible to self administer CPR but in most electrical accident cases the patient is going to be unconscious. Thus you can see the obvious problem. You could of course use a cell phone or radio and talk through it with someone remote that can get there in a couple minutes. That being said 70E and OSHA talks about two different types of energized work. Testing and visual inspection are not subject to the same requirements as say the above case of doing anything that involves manually manipulating energized conductors.

Regardless the cutoff is 50 Volts currently. There is ample evidence that 240/120 is no different. A man in Georgia was documented as a fatality from arc flash in 240 in 2009. Above 150 V the big change is that direct contact is no longer the only way to be shocked and arc flash is present. Above 1000 V voltage creep becomes an issue and “insulated” is no longer sufficient by itself to be considered safe. Above 40 kV gloves aren’t available and the work methods are shifting towards live line bare hands.
 
Code and regulation wise 480 is no different than 240 except you can have different grounding schemes. If you are not qualified for 480 don’t do any work above 50 Volts.


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paulengr said:
Electrical lockout IS energized work. You have to test live conductors to verify absence of voltage. Until that point it is considered potentially energized. That’s part of OSHA Subcgapter S for electrical (not general) lockouts. So is grounding for obvious reasons. Breaker and disconnect contacts occasionally weld together far more often than you would expect and some switchgear breakers have to be racked off the bus for lockout where you literally put the lock through the track to prevent racking it back in.
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I take your point. Yes, it was also standard procedure for us to test to ensure that the kit was dead. The highest voltage we worked on was 11kV. The test for that was a little more sophisticated. We had a prod that was about a metre long with a neon indicator. It also came with a tester. A cap that you put over the prod to make sure it was working. You did that first before using the prod and then again afterwords to make sure it was still working.
 
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