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Do you open switchgear hot?

10K views 51 replies 24 participants last post by  icdubois 
#1 ·
What saftey considerations do you guys think are relevant when considering whether to shutdown low voltage switchgear or open it live? Would you guys consider not touching the components mitigating the risk of live equipment?
 
#11 ·
We had an engineer that wanted us to remove the covers on a 14,000 volt transformer and vacuum the dust off it live. Pulled the documentation for it and read it out loud at a maintenance meeting on the planning of this foolishness. He started to argue, but had give up when he couldn't even explain the parts and pieces of the apparatus. I was the oldest electrician there and stood my ground. It was get fired, quit or win. We didn't vaccum the transformer. I did leave after a while. Couldn't work for that fool any more.
 
#34 · (Edited)
sounds like our engineer:laughing:

why is it when someone gets an engineering degree it squeezes out any real intelligence?:eek:


when i first started the job they had contractors in the plant installing equipment and one of the carton incline belts was about 4 inches below the support cross-member for the machine and the cartons were 16 inches tall!
the engineer was bragging up the install to the ceo when i asked him how in the hell was the box supposed to fit under the frame?:blink:

ceo was not impressed with that design

and as to the original question! absolutely not
 
#12 ·
I work 120/208/240 gear live all the time. I used to open up 480 stuff without a second thought. But as I get older, and more videos appear of the volcanic meltdowns at that voltage, I tend to shut that down. Occasionally I'll open up a 277 lighting panel or something, but switchgear has me spooked.
 
#15 ·
Never. I have to pull a 480v switchgear every now and then and I never do it live.

The electricians that work for Caterpillar wear full PPE (arc flash hood, the whole getup) when pulling a switchgear and as far as I know never do it live.
 
#16 ·
Big John said:
Hinged doors, no problem. Bolted covers I get a lot more uncomfortable and want to be in full PPE. I have pulled off several covers and found energized parts stupid-close to the frame where if someone even leaned against it too hard, it might've shorted. No thanks.
I was opening up an old FPE dry unit sub once during an IR inspection. Pulled one of the 7' tall covers off of the transformer section, set it aside, and as I looked back at the opening, I saw the primary bus (12,470) staring me in the face about 3-4 inches from the plane of the cover. Ironically, the 480V bus was well inside the footprint of the gear.
 
#17 ·
Yeah, unless I can look through an opening and see there's nothing nearby, I ain't risking it for exactly that reason. I've pulled a couple covers where you could see somebody before me was unlucky and theres a big scortch mark that lines up perfectly with a piece of nearby bus.

And honestly, that's the best scenario. Worst case you burn down everything in the room, you included. I don't much worry about being electrocuted, but I could definitely do without the risk of being set on fire.
 
#28 ·
NC Plc said:
Yes, at least in this situation. Caterpillar are very, very safety focused.
Are you sure they aren't suiting up just to pull the covers and check for dead?
Well I honestly can only speak for the instance where we were looking for issues with this paticular piece of equipment, he suited up when he racked it out and said cat required it.

It's a good thing he was there though, he found where a ground was rubbing against a 480v 600a... I forget the name. A piece of metal that one of the 3 phases hooked to that typically has 550a on it. We were very close to a catastrophic failure.
 
#31 ·
Yes

I open energized switchgear for inspections, but only when protected by the appropriate PPE.
If it's the secondary of a 2500 kVA, 480 volt transformer, with an incident energy level of 130 calories, then I won't open it.
But if it's 8 calories, then I'll wear my level 2 PPE and carefully open the door or remove a bolted cover for access.
I teach an NFPA 70E class where I emphasize that before you take any level of risk, know what you're exposing yourself to so you can stay protected. Use the 2015 70E tables 130-7(C)(15)(A)(a&b) for determination of the appropriate PPE for the equipment, or use the calculated levels posted on an arc-flash label.
And be aware of the actual location of the bus, because the working distance used in the arc-flash calculations is from that bus, so if a label on the equipment shows 30 calories for a working distance of 18" and you open the gear and the bus is actually 18" deep in the gear, then you've doubled the working distance and likely reduced the incident energy exposure by about 60% of what it would be from the face of the gear. That's a way to stay safe when wearing PPE 2 and opening a 15 calorie-labeled piece of equipment.
 
#39 ·
Zog said:
70E is pretty clear that removing panels (Hinged or bolted) to expose live parts presents and arc flash hazard and requires the proper PPE per the arc flash label.
While I do feel a lot better about opening a hinged cover than removing a bolted one, the hazard is still there. I can remember one incident during an inspection where I swung the door open on a 600V 600A disconnect, mounted about 5' off the floor, only to have the door come crashing to the ground inches away from me. Scared the hell out of me and everyone else in the area. The thing could have just as easily twisted into the lugs of the switch as it fell. Turns out the hinge pins were never set down into the hinges.
 
#46 ·
cdnelectrician said:
How the heck did you put the cover back on! That would have been a bit scary. The clearances on some gear boggles my mind. I was working on a transformer the other day (27.6KV - 347/600) that has not been turned on yet. The primary lugs are barely 6 inches from the front cover.
Very carefully.

I swear it's like the engineers designing this stuff get a bonus for getting the live parts as close to the can as possible without actually causing a flashover.
 
#47 ·
I learned, through sheer luck, that energized or not, you need to be careful opening up gear.

I was once opening a large Square D MDP that has those stupid wings that catch the back side of the lip on the can.

Fully expecting their to be a foot on the bottom of the cover that would support the weight, I only held pressure against the can while undoing the last screw to prevent it from tipping out as they are rather top heavy.

I don't know the weight of that cover but heavy comes to mind. When the last screw loosened enough, the entire thing slid like a guillotine to the floor.

If my feet had been an inch closer I would probably have no toes.

Upon closer inspection I saw no indication that the foot was only missing. It looked as if it was never there. No spot weld marks, no holes, no missing paint.

I kindly left a note for anyone in the future in indelible marker.
 
#52 ·
I was recently working on an install where we needed to cut a 6" raceway from the drive to the gear sitting adjacent. There was about a 1/4-1/2" gap between them. The gear was 480v 1200a. The main could be shut off but there was still the area where the feeders landed on thin lugs. I made it very clear that I was not going to cut that access unless the poco came and opened the transformer. Some one else ended up cutting the access, with the line side of the main still hot. I think they got lucky nothing happened.
 
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