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Old 11-22-2015, 05:23 PM   #21
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Wait, Im confused, why is opening MV safe then LV?
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Old 11-22-2015, 05:27 PM   #22
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What? Was the equipment unable to be effectively LOTOd?
Actually, yea. The only way to truly LOTO the equipment is to pull the switchgear, effectively severing the connection between it and the utility. The utility side is almost always live, with the only exception being when the recloser on the pole opens.

I typically call the utility and have them open the recloser any time I rack it out.
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Old 11-22-2015, 05:27 PM   #23
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Great. You're carefully trying to open a this old piece of energized gear, and right as you get a the door off some ancient dog of a 2000A main slams open a under full load. I probably wouldn't need any more caffeine that day.
But you would require new pants that day...

And maybe a new shirt for the guy behind you!
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Old 11-22-2015, 07:56 PM   #24
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Actually, yea. The only way to truly LOTO the equipment is to pull the switchgear, effectively severing the connection between it and the utility. The utility side is almost always live, with the only exception being when the recloser on the pole opens.

I typically call the utility and have them open the recloser any time I rack it out.
There's no way I would work downstream of a recloser if it was the only thing keeping the circuit dead. I would want to see open cutouts or a racked out breaker or something similar.
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Old 11-22-2015, 08:09 PM   #25
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There's no way I would work downstream of a recloser if it was the only thing keeping the circuit dead. I would want to see open cutouts or a racked out breaker or something similar.
Yea it's not the smartest setup but its around 20 years old . 5 more years or so and it's going to be decommissioned.
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Old 11-22-2015, 08:51 PM   #26
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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?
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Old 11-22-2015, 08:56 PM   #27
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There's no way I would work downstream of a recloser if it was the only thing keeping the circuit dead. I would want to see open cutouts or a racked out breaker or something similar.
Yeah, an air break is definitely ideal, there's a reason 225.51 requires it.

But we still run into half-ass installs where the recloser is the only means of isolating the line. Dump it, test for bad interrupters, pull the control power, lock the controller, and hang grounds.
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Old 11-22-2015, 09:19 PM   #28
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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.
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Old 11-22-2015, 09:26 PM   #29
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Why are you taking the chance? Even if the odds are a million to one that an "oops" won't happen on the "live" switch, the odds are zero if its dead. Better the switch dead than you.
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Old 11-22-2015, 10:01 PM   #30
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Yes I do open hot SWGR just to look or test.

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Old 11-23-2015, 10:23 AM   #31
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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.
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Old 11-23-2015, 10:31 AM   #32
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Originally Posted by Bad Electrician View Post
Older FPE were famous for Shunt Trips switches on the door.
Westinghouse used door interlocks on DB gear and some early DS gear, mechanical interlock connected to the tripper bar to trip the breaker when you opened the door. Saw a guy shut down the Dodge viper engine plant once thanks to this stupid design.
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Old 11-23-2015, 10:36 AM   #33
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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.
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Old 11-23-2015, 11:35 AM   #34
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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.
sounds like our engineer

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


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?

ceo was not impressed with that design

and as to the original question! absolutely not
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Last edited by gnuuser; 11-23-2015 at 11:53 AM.
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Old 11-23-2015, 12:29 PM   #35
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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.

...
Racking a breaker out requires full PPE, so that should happen everywhere and not just at Cat.
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Old 11-23-2015, 01:57 PM   #36
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Wait, Im confused, why is opening MV safe then LV?
Seems like a stretch to call it "safer." But often there's a lower incident energy on MV branch circuits than there would be on an LV circuit of the same power.
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Old 11-23-2015, 02:00 PM   #37
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Racking a breaker out requires full PPE, so that should happen everywhere and not just at Cat.
... actually Don, there is the case now, as shown in table 130.7(C)(15)(A)(a), where racking can be performed without PPE: Arc-resistant gear; with proper installation, maintenance, doors and covers secured, and no pending failure.
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Old 11-23-2015, 02:29 PM   #38
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... actually Don, there is the case now, as shown in table 130.7(C)(15)(A)(a), where racking can be performed without PPE: Arc-resistant gear; with proper installation, maintenance, doors and covers secured, and no pending failure.
Or with remote racking
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Old 11-23-2015, 06:25 PM   #39
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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.
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Old 11-24-2015, 01:22 PM   #40
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... actually Don, there is the case now, as shown in table 130.7(C)(15)(A)(a), where racking can be performed without PPE: Arc-resistant gear; with proper installation, maintenance, doors and covers secured, and no pending failure.
How would anyone know there is a "pending failure" before they attempted to rack the gear?
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