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#152376 - 12/18/04 06:41 PM The Elusive Delta Circuit Breaker
electure Offline

Member

Registered: 12/24/00
Posts: 4226
Loc: Fullerton, CA USA
 Quote:
I bought this on eBay. I had seen them in old catalogs, but never laid eyes
on one. Use prohibited by NEC section 384-16 (e)beginning with the 1978 edition.
The date on the box is May 27 1963, so it's almost as old as I am.


NORCAL











(edited to post clearer images)



[This message has been edited by electure (edited 01-08-2005).]

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#152377 - 12/19/04 11:30 AM Re: The Elusive Delta Circuit Breaker
Bjarney Offline
Moderator

Registered: 04/10/02
Posts: 2561
Loc: West-Southern Inner-Northeast ...
 
The reason they were no longer permitted in Article 384 went something like this — They were used to provide one 3ø circuit in a 1ø 3w panelboard. The 1ø panelboard could serve a 3ø load such as a package air conditioner in a retail store where everything else on the feeder/service entrance was 1ø.

They were shot down as a potential shock hazard—where the 1ø panelboard disconnect was opened, there could be backfeed through the highleg in the ‘outboard’/'delta' 3ø circuit through the served 3ø load.

Norcal’s pictured ‘4-space/3-pole’ breaker has 4 cable connections (lugs) and two bus clips to connect to two (1ø) ‘hot’ busses in the panelboard. The sole highleg breaker pole had ‘in and out’ cable lugs. It was a strangely fitting compliment to 4-wire delta electric service with an ‘outboard’ transformer for 240/120 4-wire (in some cases open-)delta systems.




[This message has been edited by Bjarney (edited 12-19-2004).]

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#152378 - 12/20/04 06:24 PM Re: The Elusive Delta Circuit Breaker
sandsnow Offline
Member

Registered: 09/21/04
Posts: 163
Loc: Irvine, CA, USA
Wow even though there was a potential shock hazard, it was still marked "safetybreaker" on the box!!

Very educational
_________________________
Larry LeVoir
Inspector
City of Irvine, CA

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#152379 - 12/21/04 05:41 AM Re: The Elusive Delta Circuit Breaker
NORCAL Offline
Member

Registered: 09/25/02
Posts: 807
What is called the Cutler-Hammer "Classic" now had "Safetybreaker" on the package for many years.

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#152380 - 01/08/05 09:17 PM Re: The Elusive Delta Circuit Breaker
NORCAL Offline
Member

Registered: 09/25/02
Posts: 807
Scott,thank you for replaceing the photos the detail is much clearer.

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