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#179648 - 07/25/08 05:08 PM 277 on a 480 breaker  
wiking  Offline
Junior Member
Joined: Dec 2002
Posts: 32
Florida, USA
An insta-hot I've run across is run off of one leg of a two pole 480volt breaker. It's correct for ampacity and voltage, but is this an ok condition? code violation?
ETA: The other pole is empty.

Last edited by wiking; 07/25/08 05:09 PM.

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#179659 - 07/25/08 08:35 PM Re: 277 on a 480 breaker [Re: wiking]  
resqcapt19  Offline
Member
Joined: Nov 2000
Posts: 2,148
IL
No problem other than the wasted space in the panel..that is assuming that this is 277/480Y system.


Don(resqcapt19)

#179701 - 07/27/08 09:39 PM Re: 277 on a 480 breaker [Re: wiking]  
JBD  Offline
Member
Joined: Jul 2001
Posts: 599
WI, USA
All UL489 circuit breakers are tested/rated for single pole operation.


#179705 - 07/28/08 11:45 AM Re: 277 on a 480 breaker [Re: JBD]  
Samurai  Offline
Member
Joined: May 2007
Posts: 46
Fl.
As a precaution, I would say take off the handle tie if possible, so that the breaker acts as 2 single poles
optimally, maybe it should be changed to prevent confusion about the circuit properties. It's "wrong" but is isn't.


#179709 - 07/28/08 12:45 PM Re: 277 on a 480 breaker [Re: Samurai]  
Samurai  Offline
Member
Joined: May 2007
Posts: 46
Fl.
Originally Posted by Samurai
It's "wrong" but is isn't.

"It" isn't: this was a reverse extrapolation of the code requiring adding a handle tie if 2 singles poles are used as a double pole.


#179721 - 07/29/08 09:28 AM Re: 277 on a 480 breaker [Re: Samurai]  
JBD  Offline
Member
Joined: Jul 2001
Posts: 599
WI, USA
Originally Posted by Samurai
As a precaution, I would say take off the handle tie if possible, so that the breaker acts as 2 single poles
optimally, maybe it should be changed to prevent confusion about the circuit properties. It's "wrong" but is isn't.


Never modify a factory assembled breaker.

And, all factory assembled multi-pole breakers are required to have internal "tie" mechanisms so if one pole trips they all trip.


#179723 - 07/29/08 10:25 AM Re: 277 on a 480 breaker [Re: JBD]  
renosteinke  Offline
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Joined: Jan 2005
Posts: 5,316
Blue Collar Country
JBD, can you cite a source to support that statement?


#179737 - 07/29/08 04:50 PM Re: 277 on a 480 breaker [Re: renosteinke]  
Elec N Spec  Offline
Member
Joined: Jul 2006
Posts: 33
Rochester Hills, MI USA
NEC 110.3(B) Installation and Use Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling.

To modify something that has been listed causes that item to lose its listing.

Regards,

Tony


#179747 - 07/29/08 09:43 PM Re: 277 on a 480 breaker [Re: Elec N Spec]  
renosteinke  Offline
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Posts: 5,316
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I have to disagree with statements as broad as some recently made.

I've seen far too many multi-pole breakers that were nothing but a grouping of ordinary single-pole breakers, with a rivet below and a handle tie above, keeping them together. GE is one brand that comes to mind.

There is no code, or UL, requirement for an internal trip mechanism. All that is required is that all legs open when a fault is induced on one leg; this might simply be a matter of the spring on one being strong enough to work three handles.
That. perhaps, is why not every multi-pole breaker boasts of having an internal common trip.

That said, at least once I've encountered a multi-pole breaker that did not have all poles open. Even with that same breaker, I was not able to duplicate this mis-action.
As for breakers where not all poles close .... well, nothing is perfect, and then it's time for a new one.

Handle ties are listed, so using them to 'make' a common disconnect is clearly allowed.
When such a tie is removed, leaving three independent single pole breakers - I'd be hard pressed to be able to prove that was ever done. I don't see a problem.


#179774 - 07/30/08 09:57 PM Re: 277 on a 480 breaker [Re: renosteinke]  
JBD  Offline
Member
Joined: Jul 2001
Posts: 599
WI, USA
UL says an external handle tie is not sufficient to create a common trip breaker. The NEC requires all circuit breaker poles to be opened during a fault condition, which implies a common trip. Multiple pole "switches" created by using handle ties are not the same as multi-pole breakers.

According to the UL White book:
"An external handle tie alone does not qualify as a common trip mechanism...".

Last edited by JBD; 07/30/08 09:58 PM.

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