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Big Reason To Be Safe... #178975 06/18/08 08:47 PM
Joined: Oct 2002
Posts: 482
Zapped Offline OP
Watch and wait until about 1 minute 13 seconds then see the fireworks. All that I can say is I hope both of these guys made it home.

Any ideas on what caused this? Looks to me like the tech at the box was being a bit aggressive and was maybe in a hurry. Rule number 1 and 2 to avoid when working hot.


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Re: Big Reason To Be Safe... [Re: Zapped] #178977 06/18/08 09:33 PM
Joined: Jan 2005
Posts: 5,316
renosteinke Offline
Cat Servant
I saw that ... it looks like they're pulling wire ... the sustained arcing would be consistent with a fish tape contacting the bussbars.

Re: Big Reason To Be Safe... [Re: renosteinke] #178979 06/18/08 11:34 PM
Joined: Aug 2001
Posts: 599
Nick Offline
It looks to me like he was racking in a breaker.

Re: Big Reason To Be Safe... [Re: Nick] #178982 06/19/08 02:43 PM
Joined: Jan 2005
Posts: 315
luckyshadow Offline
I am going to agree with Nick. I appears to me they are racking in a breaker. If you look close you will notice the men are cranking something in a circular motion. The same motion used to crank( rack) in a breaker in that type of gear.

Re: Big Reason To Be Safe... [Re: luckyshadow] #178983 06/19/08 02:53 PM
Joined: Jan 2005
Posts: 5,316
renosteinke Offline
Cat Servant
I stand corrected ... I looked at it again, this time at 'fullscreen,' and you're right. You can see them cranking one way, then the other, and back again ... and trading places. Looks like there was some reason it didn't want to seat ... the rest is history.

Re: Big Reason To Be Safe... [Re: renosteinke] #179005 06/20/08 07:15 PM
Joined: Nov 2005
Posts: 823
JoeTestingEngr Offline
OK, here's my guess. They had it out for maintenance and had the arc chutes out. They have open and closed gap settings to check so they use a feeler gage. Somehow they get the arc chutes back in with metal stuck between phases, They shouldn't have even had access to the 3/4" bolt or square drive to crank if the breaker was closed. So unless a failed shutter of some kind caused the fault, I'll bet they left hardware in the breaker.

Re: Big Reason To Be Safe... [Re: JoeTestingEngr] #179071 06/24/08 09:41 PM
Joined: Sep 2005
Posts: 120
Zog Offline
Joe, seriously, come on, why would you ever have a feeler gauge (in the cell) on a breaker like this? And what are you talking about they shouldnt have had access to the racking screw? This switchgear dosent have shutters so that makes no sense, you are way out to lunch on this. Sorry. How much "Maintenence" have you done on this gear?

Racking mech problem, you can se him racking in, get stuck, rack it back out, back in and torque it hard. Obviously the primary disconnects were misaligned and snapped off, common arc flash cause, operators not properly trained on the equipment. I am suprised the shear pin didnt break on the pantagraph screw like it should have before this happened.

MV/HV Testing Specialist, "BKRMAN"
Re: Big Reason To Be Safe... [Re: Zog] #179094 06/25/08 09:09 PM
Joined: Nov 2005
Posts: 823
JoeTestingEngr Offline
Zog, I was serious. I wouldn't have anything in the cell. If I had a breaker out for maintenance, the DS units that I have worked on, get their red arc chutes removed. Then we have one gap to check with the breaker open and one gap when closed. I also remember having to loosen 4 bolts because the contacts were rotated slightly on some breakers. We would then have to go through the Digi-trip settings with the Amptector. This was an activity that my group got stuck doing on regular time, 3 Saturdays a year, per contract. I'm certainly no expert from doing it 3 times a year, but I thought you couldn't lift the flap to get to the bolt on a closed breaker. I also thought that, on at least some cubicles, a shutter comes down as you rack out the breaker. Am I wrong there? I couldn't tell whose AC SWGR it was from the viewing angle but it looked like it could have been the type that I work with.

If you thought my first guess was silly, how about my second guess? They took out the main breaker and were trying to rack in a spare while they worked on the main. Guesses are guesses. No harm, no foul for a bad one.

Re: Big Reason To Be Safe... [Re: JoeTestingEngr] #179260 07/03/08 05:38 PM
Joined: Aug 2003
Posts: 99
richard Offline
That was a massive bit of arcing, Is there any more info on how it happened?

Re: Big Reason To Be Safe... [Re: richard] #179327 07/07/08 12:05 PM
Joined: Feb 2007
Posts: 65
BrianP Offline
What about PPE? What sort of PPE would normally be required for breaker maintenance (assuming that is what they were doing)?

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