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#109656 - 11/17/05 10:33 PM How'd This Happen?  
electure  Offline


Member
Joined: Dec 2000
Posts: 4,262
Fullerton, CA USA
One of the guys was unscrewing a blank cover on a different box about 100' away when he heard the pop inside the box he was working on. The screw had apparently rubbed a conductor raw inside.

The simultaneous sound of this one kind of made it hard to hear, though.




[Linked Image]


[Linked Image]


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#109657 - 11/17/05 10:52 PM Re: How'd This Happen?  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
Just a guess that one of the switches was not happy with the available fault current.

That is really ugly.


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#109658 - 11/17/05 11:22 PM Re: How'd This Happen?  
Trumpy  Offline


Member
Joined: Jul 2002
Posts: 8,223
SI,New Zealand
Scott,
What make/brand switches are those?.


#109659 - 11/17/05 11:54 PM Re: How'd This Happen?  
frenchelectrican  Offline
Member
Joined: Feb 2003
Posts: 939
Wi/ Paris France { France for ...
i am sure it look like Hubbel 2 pole switch but the Pass & Syemour look very simuir too but i am not too sure about Levetion they look little diffrent

i can tell this was wired up on 277/480 volt circuit

if running more than 300 volts it should have " divider " on there and i dont see any of it in the switch box at all.

the other thing i can see that the switch is allready wired on 480 volts [Linked Image] so that get more spooky there

Merci, Marc


Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)


#109660 - 11/18/05 01:15 AM Re: How'd This Happen?  
Lostazhell  Offline
Member
Joined: Feb 2004
Posts: 1,431
Bakersfield, CA (Originally Or...
Were these 4ways or 2pole switches? If they're 2 pole, and there was 480V being run through these, the fault downstream (I'm assuming) probably found its weakest link being the switch contacts not being rated for the fault voltage.. But you say a faceplate screw caused the fault which would be at 277V if all was grounded properly, or did more than one wire get damaged?

The switches are Hubbell, you can make out their oval insignia above the toggles on the yokes...


#109661 - 11/18/05 08:26 AM Re: How'd This Happen?  
electure  Offline


Member
Joined: Dec 2000
Posts: 4,262
Fullerton, CA USA
Yup, Marc's right. (I told the answer on the chat, which may have helped [Linked Image])
2 Poles, Hubbell, with a label on the side "2 Pole for single circuit only".

The installer chose to disregard the label, and ran 480V through them. The fault was 277V, caused by 8-32 in the corner of a 4-S box. The switch on the left took the fault, and its failure sent this "Jack and the Beanstalk" effect into high gear.

There were 18 of these switches installed (that's 36 circuits). The customer had me remove all of them [Linked Image]
They will be replaced with contactors.
(BTW, None of the 20 Amp breakers tripped)



[This message has been edited by electure (edited 11-18-2005).]


#109662 - 02/02/07 08:02 PM Re: How'd This Happen?  
electure  Offline


Member
Joined: Dec 2000
Posts: 4,262
Fullerton, CA USA
[Linked Image]

Here's what I found instead of contactors when I happened by the place again.


[Linked Image]


Now what ??

[This message has been edited by electure (edited 02-02-2007).]


#109663 - 02/02/07 08:33 PM Re: How'd This Happen?  
Theelectrikid  Offline
Member
Joined: Apr 2004
Posts: 810
Levittown, PA
Where's that rolleyes smiley, wait, here it is! [Linked Image]

Whaddaya expect? Someone to spend money replacing the old switches with new contactors?

(BTW Scott, no cursing. [Linked Image] )

Ian A.

[This message has been edited by Theelectrikid (edited 02-02-2007).]


Is there anyone on board who knows how to fly a plane?

#109664 - 02/03/07 07:48 AM Re: How'd This Happen?  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
To quote a character from an old British movie about a couple fixing up an old house (including wiring):

"They never learn!"


#109665 - 02/03/07 11:16 AM Re: How'd This Happen?  
Lostazhell  Offline
Member
Joined: Feb 2004
Posts: 1,431
Bakersfield, CA (Originally Or...
I wonder if this is why the code wants dividers for >300V.. to block the shrapnel from the other switches. [Linked Image]

I have an old GE 3P toggle switch rated 20A 600V if they're really against the contactors, they might want to look into them. I'm sure they're not cheap though. Here are the ones from P&S..

edited to fix link

[This message has been edited by Lostazhell (edited 02-03-2007).]


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