ECN Forum Forums Safety Discussion and News Occupational Safety Discussion 13,800 transformer

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

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!)

John,
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.

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.

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

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.

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.

It was so very nice of several of you to make reference to OSHA and NFPA 70E.....unfortunately, those references are, well, irrelevant. So, it turns out, is the NESC.

Our poster said the DOE inspector.....so this was somewhere that the DOE- and not OSHA- had jurisdiction. I suspect the jurisdiction of the DOE is severely limited, probably to their facilities alone.

A look at the appropriate DOE standard (DOE-HDBK-1092-98) shows that the DOE requires, for work above 600 volts and under 15KV, the following PPE:
(If jacking a breaker out), jacking tools, safety glasse, gloves, sleeves, and fire resistant clothing;
(If pulling fuses), fuse puller, hot stick, safety glasses AND face shield,gloves, sleeves, mat, and fire resistant clothing.

A big thank you to Mike Holt, who ran down this material for us!

At the power company I used to work for, we were required to wear a hard hat, FR shirt, all natural fiber clothes, steel toes, safety glasses, and rubber overshoes when switching in a substation using sticks. For operating any gang switches, 25kV rubber gloves were required also. The sticks are tested every couple of years. If they passed then they should provide insulation of at least 100kV per foot.

When switching on pole mounted equipment, i.e. reclosers, fused cutouts, etc., from the ground using zipsticks, we didn't have to have the rubber overshooes or rubber gloves as the stick should provide plenty of insulation.

Wes

Just to give additional information on the Equipment. It is a GE Transformer Three Phase, Pad Mounted Distribution Transformer for underground services. Here is a link to the Manual for the Transformer http://www.geindustrial.com/products/brochures/GEI-79025M.pdf. The switch is shown on Pp. 16 Figure 23. of the manual and is described as a Loop Switch with On-Off radial switch. The manual states, "The radial-feed, two position internalm oil switch is a gang-operated loadbreak switch. It is operated by a hot stick and uses manually charged overtoggle storage spring assembly that is independent of operator speed. The spring loaded operating mechanism ensures quick load breaking and load making operation. It can be used to de energize the transformer. The operatiing handle and name plate are located in the high voltage compartment. Load sheding was performed pior to de energizing this switch.

Paul,

Operating a padmount like that our guys would be required to have all natural clothing, FR shirt, steel toes, rubber overshoes, rubber gloves, safety glasses, and a minimum 6' shotgun stick, 10' if possible.

I know some may argue that rubber overshoes are over kill, but with the moistness of the SE US, better to be safe than sorry.

As for the face shield, my current employer is starting to require them for setting and removing meters, but not for switching or line work.

Wes

Guys,
That Lineman was me and I stand by my comments.
The Hot-Stick as I use it is PPE, after all it is made of insulating materials and could be called your second layer of PPE.
The part of it that is the tool, is the tip, which you do work with (is it not?).
It is usually metallic, but it is isolated from the part that is held (Or am I wrong?)
I am also assuming that usual PPE is worn, as in Helmet, Safety Glasses, Gloves and Protectors.

I think Don was OK in asking for some 'documentation' that isentified a 'hot stick' as PPE.
It may not have been clear in my posting of the DOE rules, but "hot stick" is one of the types of PPE listed on their chart, along with gloves, etc.

And Mike, you are quite right- most folks have absolutely no ide of the dozens of tools made to be attached to a hot-stick. Hot-sticks are completely useless without some sort of tool attached to the tip; most of us non-PoCo types have only seen the "finger" attachment, and may not realise that there are other tips as well!

Mike,
How is a hot stick different from any other type of insulated tool that would be used on energized circuits?
Don

Don,
Good question.
The hot-stick has a different status mainly because of the seperation distance provided between the worker and the hazard.
Over here, hot-stick work has it's own training regime.
Like I said above, the only conducting part of the stick is the tip and the tool attached to the end of it, which you may notice is often shorter than 5".
A lot of training goes into using our collapsable and also rigid sticks here.
As John mentioned there are a lot of tools that we use on the ends of our hot-sticks.
I'll see if I can find a manufacturer link to some of the gear used.
I'm also trained in Live Glove and Barrier work, which is a lot "easier" than Hot-stick work.
LG & B is "hands-on" ,Hot-stick work is done from a distance usually 20ft here.
To sum up Don,
It's distance that counts.
I know I like it!.

After downloading and reading the manual for this transformer, Some thoughts come to mind in reference to Paul's posts:

The shutdown was accomplished using the transformer's built-in switch. So, it seems possible that the incoming cable terminations (even if "separable insulated connector" type) would still be energized and accessable in the HV compartment. Definitely would need PPE in that case, I don't think any less - restrictive requirements in the equipment manual would sway the inspector's opinion. The presence of the baffles referred to in the manual would not matter I think.

However, the manual allows for "rated glove only" operation of the internal switches. (Don't think I'd want to be near a faulted transformer to turn a disconnect switch by hand!)


I did have an incident some years back where a 480 pri 120/240 sec transformer failed at a cinema and I was asked to shut it down. (Old style SqD fused switchgear.) I did not have proper PPE and refused. We put in an emergency call to their electrician and the fire dept. The electrician arrived, suited up and shut it down. Thankfully it was a low-level fault in the secondary, lots of smoke but no boom.

As a side note, the direct link didn't work for me. I had to enter the transformer model # in the "Search" field. (79025M) That brings up a list of all the product brochures, scroll down to the full model #.

Trumpy:

Do you always use gloves with hotsticks? (Assuming distribution class under 40kV.) IIRC in the Air Force, thier distribution crews were forbidden to wear gloves when using hotsticks! The logic was that gloves would prevent one from feeling the "fuzziness" caused by a hotstick which was marginal in withstand ability. Sounds illogical and dangerous to me.

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[This message has been edited by mxslick (edited 08-21-2005).]

We had to have Hanford Utilities come out yesterday and shut down the 13,8 Primary. We expect them only disconnect at the pole. They did not. They, in front of this same inspector, used only a 6 ft. hot stick. Both linemen wore short sleeved shirts, no voltage rated gloves and what ever they wore from home. Inspector made no issue what so ever even though she could of since it is a requirement that anyone that comes on the project must use project procedures including 70E.

First off there is no such thing as 20kV gloves, I assume you are refering to a class 2 glove that is tested at 20kV but rated for max use of 17kV. Thats OK since you were working on 13.8kV.

Second, the DOE inspector is right about the FR clothing requirement (if 70E is required to be followed on-site), several posts (I.E Ron)had the correct reason for this. Remember Arc flash boundaries apply even when the live parts are not exposed, shock boundaries (LAB, RAB, PAB) only apply when the live parts are exposed. (If you say there were no energized parts, then why the hotstick and gloves?)From the sounds of it this transformer has exposed live parts in the HV section (Lighting arrrestors)

Third, hot sticks are considered PPE per the 70E. They should be tested every 2 years if used as a primary means of shock protection, your gloves were your primary means of shock protection (If tested within the last 6 months) so you are OK on that one.

Basically, you are going to have a hard time defending you position, instead you may want to look at getting some(quality)70E training.