ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat Box
Recent Posts
Square D "All-In-One" Panelboard
by gfretwell - 02/18/20 07:38 PM
15 amp outlets removed due to cell phones
by mbhydro - 02/13/20 11:38 PM
2020 code
by shortcircuit - 02/11/20 04:30 PM
Anyone use rubber amalgamating tape?
by gfretwell - 02/06/20 11:17 PM
Danish type K Sockets
by djk - 02/06/20 06:52 PM
New in the Gallery:
Facebook follies, bad wiring
FPE in Germany pt.2
Who's Online Now
0 registered members (), 61 guests, and 7 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Page 1 of 2 1 2
4000A 480V Duct #124477 10/10/06 09:29 PM
Joined: Oct 2000
Posts: 3,592
Admin Offline OP
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....

[Linked Image]

[Linked Image]

[Linked Image]

Tools for Electricians:
Re: 4000A 480V Duct #124478 10/11/06 12:29 AM
Joined: Dec 2004
Posts: 23
Av-guy Offline
What is a "Pringle switch"? BTW, How long did they take to restore power?

Re: 4000A 480V Duct #124479 10/11/06 05:58 AM
Joined: Dec 2005
Posts: 859
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.
Re: 4000A 480V Duct #124480 10/11/06 07:54 AM
Joined: May 2005
Posts: 984
ghost307 Offline
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.

Re: 4000A 480V Duct #124481 10/11/06 04:52 PM
Joined: Feb 2005
Posts: 361
Celtic Offline
Wasn't it megged ?

~~ CELTIC ~~
...-= NJ =-...
Re: 4000A 480V Duct #124482 10/11/06 06:03 PM
Joined: Mar 2005
Posts: 169
steve ancient apprentice Offline
Only one comment,
Glad no one got hurt and WOW

Re: 4000A 480V Duct #124483 10/11/06 08:37 PM
Joined: Nov 2001
Posts: 745
mamills Offline
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).]

Re: 4000A 480V Duct #124484 10/11/06 09:02 PM
Joined: Jul 2004
Posts: 129
hypress Offline
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.

Re: 4000A 480V Duct #124485 10/13/06 09:08 PM
Joined: Oct 2004
Posts: 803
mxslick Offline

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.
Re: 4000A 480V Duct #124486 10/14/06 10:12 PM
Joined: Mar 2006
Posts: 52
TwinCitySparky Offline
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...

Page 1 of 2 1 2


2020 National Electrical Code
2020 National Electrical
Code (NEC)

* * * * * * *

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman


Member Spotlight
Posts: 201
Joined: April 2004
Show All Member Profiles 
Top Posters(30 Days)
dsk 11
djk 6
Admin 3
Popular Topics(Views)
263,469 Are you busy
198,558 Re: Forum
187,481 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.3