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#150653 - 08/06/05 10:49 AM 13,800 transformer
Paul O'Connell Offline
Member
Registered: 07/02/05
Posts: 56
Loc: Allen Park, Mi. USA
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.
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Arc Flash PPE Clothing, LOTO & Insulated Tools
#150654 - 08/06/05 02:01 PM Re: 13,800 transformer
Ron Offline
Member
Registered: 03/13/02
Posts: 582
Loc: White Plains, NY
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.
_________________________
Ron
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#150655 - 08/06/05 03:37 PM Re: 13,800 transformer
resqcapt19 Offline
Member
Registered: 11/10/00
Posts: 2148
Loc: IL
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
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#150656 - 08/06/05 04:14 PM Re: 13,800 transformer
renosteinke Offline
Cat Servant
Member
Registered: 01/22/05
Posts: 5316
Loc: Blue Collar Country
I think he's describing a situation where the hot stick is used to turn a handle.....not only are you not able to see any live parts, but the stick holds you ten feet away.

This sounds similar to the practices I've seen with our power company.

Isn't one of the functions of the hot stick to let you work "outside the zone?"

(I know very little about this HV stuff- please enlighten me!)
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#150657 - 08/06/05 06:01 PM Re: 13,800 transformer
Trumpy Offline


Member
Registered: 07/05/02
Posts: 8211
Loc: SI,New Zealand
John,
Quote:
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.
_________________________
Let's face it, these days if you're not young, you're old - Red Green grin
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#150658 - 08/06/05 09:06 PM Re: 13,800 transformer
resqcapt19 Offline
Member
Registered: 11/10/00
Posts: 2148
Loc: IL
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
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Don(resqcapt19)
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#150659 - 08/07/05 10:51 AM Re: 13,800 transformer
renosteinke Offline
Cat Servant
Member
Registered: 01/22/05
Posts: 5316
Loc: Blue Collar Country
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.
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#150660 - 08/07/05 08:17 PM Re: 13,800 transformer
resqcapt19 Offline
Member
Registered: 11/10/00
Posts: 2148
Loc: IL
John,
The OSHA rules for lineman and utilities are far less restrictive than the ones for electricians. I would want to see a statement in 70E or OSHA to the fact that a hot stick is not a tool.
Don
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#150661 - 08/08/05 03:23 AM Re: 13,800 transformer
George Corron Offline
Member
Registered: 05/16/01
Posts: 717
Loc: Lorton, Va USA
Guys,
I am ASSUMING that these are like the dead front transformers we use in the East. Load break elbows on the high side, closable secondary side. NO LIVE PARTS are EVER exposed.

Trumpy, usually we don't use any circuit breakers at all on the high side, just oil encased fuses, and they are also not exposed, of course.

The only requirements are fire resistant clothing. Using gloves, sleeves, and a 6 - 10' shotgun stick.
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#150662 - 08/08/05 05:06 AM Re: 13,800 transformer
Ron Offline
Member
Registered: 03/13/02
Posts: 582
Loc: White Plains, NY
NFPA 70E Table 130.7(C)(9)(a) requires Category 2 PPE for switch operation with enclosure doors CLOSED.
So even if there are no energized parts visible, OSHA require PPE via 70E.
_________________________
Ron
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