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#124477 - 10/10/06 07:29 PM 4000A 480V Duct
Webmaster Offline


Registered: 10/07/00
Posts: 3142
Loc: NY, USA
If you have a 4000A pringle switch trip, make sure you take a look before you try to close it. Here is what I know...

480V 4000A AL Duct in a 14 story building in Arlington, VA. Pringle switch tripped and was reset and a fireball consumed a good portion of the 14th floor. Every 90 blew out (holes large enough to stick an arm much bigger than mine through) from the 14th to the sub-basement parking garage where the service is located. The true cause of this failure is known by few people, and I am not one of them. Just a reminder of the forces that we deal with. This happened over the 4th of July, so thankfully no one was injured. This could have been a lethal disaster. It wasn't....


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#124478 - 10/10/06 10:29 PM Re: 4000A 480V Duct
Av-guy Offline

Registered: 12/28/04
Posts: 22
Loc: Bangkok,Thailand
What is a "Pringle switch"? BTW, How long did they take to restore power?

#124479 - 10/11/06 03:58 AM Re: 4000A 480V Duct

Registered: 12/08/05
Posts: 862
Loc: Titirangi, Akld, New Zealand
Amazing !!

LV faults near high capacity transformers 1 or 2 MVA or bigger have enormous amounts of power and destructive capacity as seen in these photo's.

Someone would have been very shaken and needed to change some un%$^s when closing that switch.
The product of rotation, excitation and flux produces electricty.

#124480 - 10/11/06 05:54 AM Re: 4000A 480V Duct
ghost307 Offline

Registered: 05/09/05
Posts: 883
Loc: Chicago Illinois USA
A "Pringle Switch" is a generic term used in reference to 100% rated Bolted Pressure Switches. The most common manufacturer used to the the Pringle Electric Co.

Here's the URL to a page that Eaton has about them.

#124481 - 10/11/06 02:52 PM Re: 4000A 480V Duct
Celtic Offline

Registered: 02/26/05
Posts: 367
Loc: NJ
Wasn't it megged ?
~~ CELTIC ~~
...-= NJ =-...

#124482 - 10/11/06 04:03 PM Re: 4000A 480V Duct
steve ancient apprentice Offline

Registered: 03/04/05
Posts: 170
Loc: west springfield,mass
Only one comment,
Glad no one got hurt and WOW

#124483 - 10/11/06 06:37 PM Re: 4000A 480V Duct
mamills Offline

Registered: 11/30/01
Posts: 739
Loc: Wharton, Texas, USA
What did the pringle switch look like after this "event"? I know virtually nothing about this type of switchgear. Is PPE required for someone operating this equipment (or at least a real good idea)?

Mike (mamills)

[This message has been edited by mamills (edited 10-11-2006).]

#124484 - 10/11/06 07:02 PM Re: 4000A 480V Duct
hypress Offline

Registered: 07/20/04
Posts: 132
Loc: Charleston WV
The plant has several Pingle switches.Most of them were installed mid 70s to late 80s. We have then on a RM program and we clean and lubricate the blades of the switches. We found that if you dont RM they may not open porperly. Ours are fused switches not electricaly operated . Pringles switches are bolted pressure contact switches and when the knives contact the stationary contacts they actualy have a cam on each knife that generates additional force to help ensure greater contact pressure.
To those who have not seen a Pringle switch they look like a custom made device not something mass produced a lot of pride goes into them.

#124485 - 10/13/06 07:08 PM Re: 4000A 480V Duct
mxslick Offline

Registered: 10/24/04
Posts: 785
Loc: Atomic City, ID USA

What was the cause of this failure, or are you not at liberty to say?

"Violent" is too small a term for this one.....
Stupid should be painful.

#124486 - 10/14/06 08:12 PM Re: 4000A 480V Duct
TwinCitySparky Offline

Registered: 03/23/06
Posts: 52
Loc: Minnesota
480V 4000A AL Duct in a 14 story building in Arlington, VA. Pringle switch tripped and was reset and a fireball consumed a good portion of the 14th floor.

I'd venture to say they had two major failures. I think the first more obvious than the second...

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