We had a failure in a 13,800 substation. We had to shut down the 13,800 side of the transformer. We had the electricians use a hot stick and 20,000 volt rated glowes. The DOE inspector violated us for not doing a ARC Flash Calc and using protective clothing and Face shield. We tried to explain to her that actually none of the above were required since 70E requires PPE to be used when exposed to live parts. This transformer had no exposed live parts and the breaker was oil emersed using FP3 cooper oil. We explained if there were live parts and arc flash calc were used it would be in excess of 156 cal. and the utility would have to be contacted to totally shut down the project. At 156 cal, there is no PPE that would properly protect these electricians. For example at 46 cal. a face shield would melt.
I would greatly appreciate so opinions so I can defend our position.
Paul, I agree with OSHA. You choices in NFPA 70E include following Table 130.7(C)(9)(a) which requires Category 2 PPE for switch operation with enclosure doors closed, or you could have performed the detailed calculation. Sounds like you performed the detailed calc to result in 156 cal/cm^2. At 156 cal/cm^2 you could not operate the switch since the highest recognized PPE by 70E, is up to 40 cal/cm^2. BTW, 156 sounds high since your calculation should have been at a big working distance due to the use of the hot stick.
Paul, I also agree with OSHA. Causing a tool to make contact with a live part or letting the tool or any part of the person to be within the prohibited approach distance is "exposed to live parts". I don't see any way that you can do this work in compliance with the safety rules other than having the line side shut down by the utility. Even after the utility is shut down, you would still need the same PPE to prove the absence of voltage. Don
Isn't one of the functions of the hot stick to let you work "outside the zone?"
That's what the hot-stick is designed for. Not only does it insulate you from dangerous high voltages, but it also keeps you back from any arc-flash that could occur. The only metal part of the stick is the tip, the rest of it is Fibre-glass. One question Paul, how long was the Hot-stick?. There is a difference between a Hot-Stick and a shorter Switching Stick. The other thing you have to think about though, is not so much the risk of an arc flash, but the risk of the Oil-Filled CB exploding, they have been known to do this before today, internal faults can go un-noticed until the operating mechanism is moved.
Re: 13,800 transformer#150658 08/07/0512:06 AM08/07/0512:06 AM
John, I think that under 70E if you cause a tool, even an insulated tool, to contact the live parts, that you are "exposed to the live parts PPE is required. I don't have a copy of 70E at home to check. Also, it is very likely that give the available fault current, even using the hot stick will not place you outside of the arc flash area. I have seen calculations for MCCs that required level 2 or 3 protection over 10' away. Maybe this would not apply, if the hot stick is used to turn the operating handle of an enclosed switch, but I was thinking of the hot stick being used to pull a cut out. Don
In a discussion with a lineman, his comment was: "A hot-stick is not a tool...it is considered PPE."
I hope some PoCo types weigh in with their comments; I seem to recall a PoCo training film that showed transformers being "unplugged," and the connectors capped, by guys using hot sticks only, without any additional PPE.