two-pole breakers vs two one-pole breakers

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Coppersmith

Coppersmith

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Tampa, FL, USA
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Electrical Contractor
Is there anything wrong with using a two pole circuit breaker (with an internally tied trip mechanism) in place of two single pole circuit breakers?

Is it OK to remove the external tie bar? On BR breakers for example, these just pop off.

Is it OK to use two single breakers in place of a two pole and just add the external tie bar?
 
Coppersmith said:
Is there anything wrong with using a two pole circuit breaker (with an internally tied trip mechanism) in place of two single pole circuit breakers?
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Perfectly fine, although an inconvenience if one circuit has a problem in that both will trip.



Coppersmith said:
Is it OK to remove the external tie bar? On BR breakers for example, these just pop off.
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Probably a listing violation

Coppersmith said:
Is it OK to use two single breakers in place of a two pole and just add the external tie bar?
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Perfectly fine again as long as the circuit does not require a common trip, handle ties are available from all manufacturers, see 240.15(B)

Roger
 
240V loads such as a water heater require a 2-P breaker w/common trip, can't use two SP breakers w/ties. That's what Roger was alluding to.
 
Coppersmith said:
Is there anything wrong with using a two pole circuit breaker (with an internally tied trip mechanism) in place of two single pole circuit breakers?

Is it OK to remove the external tie bar? On BR breakers for example, these just pop off.

Is it OK to use two single breakers in place of a two pole and just add the external tie bar?
Click to expand...

No

If you remove tie bar there is still internal common trip mechanism, if one pole trips they both do. Listing and this modification is another thing.

Handle ties on two single pole is common practice on MWBC's. Roger pointed out section that allows this for things like a 240 volt 2 wire circuit- but note it does say single phase - three phase you do need a common trip unit. That said over 30 amps you don't find single pole breakers as easily and even if you did a two pole unit probably cost less anyway.
 
You also cannot use handle-ties on single poles for a 3-wire circuit to a range or similar load.
 
infinity said:
You also cannot use handle-ties on single poles for a 3-wire circuit to a range or similar load.
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Which seldom gets violated as it isn't as easy to find 40 and 50 amp single pole breakers as it is to find 40 and 50 amp two pole breakers.
 
roger said:
So, what do you say to the illustration below for "single utilization equipment"?



Roger
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I am getting lost here, I was trying to say a dryer circuit is MWBC according to that section.

What am I missing?

Edit: I only saw two SP breakers and a dryer.

I looked at back at what Rob actually wrote. Missed the part about the handle tie.:ashamed1:

Sorry:slaphead:
 
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jumper said:
I am getting lost here, I was trying to say a dryer circuit is MWBC according to that section.

What am I missing?

Edit: I only saw two SP breakers and a dryer.

I looked at back at what Rob actually wrote. Missed the part about the handle tie.:ashamed1:

Sorry:slaphead:
Click to expand...

:thumbsup:

Roger
 
roger said:
No you don't, you need to go to 240.15(B)(3) for that info Roger
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Ok we both at least partially wrong - last part of that says "and the voltage to ground does not exceed 120 volts".

Not only would a 480 volt system require three pole breaker but I would think a 240 volt high leg delta would also also require three pole breaker because the high leg is more then 120 volts to ground, not to mention you won't find a 240 volt rated single pole breaker unless you go to 277/480 (or 600) volt series breakers/panelboards.

Mostly leaves the handle tie option only applying to 208/120 systems.
 
kwired said:
Ok we both at least partially wrong - last part of that says "and the voltage to ground does not exceed 120 volts".
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No, you stand alone, I never said anything about over 120 volts to ground and the article section I pointed you to is clear on that.

Roger
 
Little Bill said:
240V loads such as a water heater require a 2-P breaker w/common trip, can't use two SP breakers w/ties. That's what Roger was alluding to.
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roger said:
Bill, read 240.15(B)(2)

Roger
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infinity said:
You also cannot use handle-ties on single poles for a 3-wire circuit to a range or similar load.
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roger said:
What are you basing that on?

Roger
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Roger, I used to think handle ties were allowed for any 2-P load but I read somewhere in the code stating that a 2-P breaker had to be used with certain loads, which I assume probably requires a common trip. But for the life of me I can't find where I read that and it's just been a few days ago and I read it before a while back as well.
So in a "court of law" I am doomed because I can't show my evidence. :(

Looks like Rob may have read the same thing but he is MIA at the moment!;)
 
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Little Bill said:
Roger, I used to think handle ties were allowed for any 2-P load but I read somewhere in the code stating that a 2-P breaker had to be used with certain loads, which I assume probably requires a common trip. But for the life of me I can't find where I read that and it's just been a few days ago and I read it before a while back as well.
So in a "court of law" I am doomed because I can't show my evidence. :(

Looks like Rob may have read the same thing but he is MIA at the moment!;)
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Look at 240.15(B).

Edit, Roger already cited this.:slaphead:

Wait found this.

http://forums.mikeholt.com/showthread.php?t=154201&p=1492260#post1492260
 
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jumper said:
Look at 240.15(B).
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I'm was referencing 240.15(B)(2) which allows the single pole CB's with handle-ties when the loads are only line to line. Not sure why the NEC makes this distinction as to the type of load but I guess that if you used the SP's for something like a dryer one CB could trip while leaving the other energized.

240.15(B)(2) Grounded Single-Phase Alternating-Current Circuits. In grounded systems, individual single-pole circuit
breakers rated 120/240 volts ac, with identified handle ties, shall be permitted as the protection for each ungrounded
conductor for line-to-line connected loads for single-phase circuits
Click to expand...
 
infinity said:
I'm was referencing 240.15(B)(2) which allows the single pole CB's with handle-ties when the loads are only line to line. Not sure why the NEC makes this distinction as to the type of load but I guess that if you used the SP's for something like a dryer one CB could trip while leaving the other energized.
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See the second illustration on the right in post #11

Roger
 
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