# 3 pole vs 2 pole



## raider1 (Jan 22, 2007)

There is no NEC section that prohibits putting a single phase load on a three pole breaker.

It is not a great design but not a code violation.

Chris


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## Mountain Electrician (Jan 22, 2007)

I've done it more than once over the years, but at the very least it's not real cost effective. I always put A on A and B on C, not that it matters, just the way I've always done it.


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## dcc (Mar 19, 2007)

Neither of the devices cares whether it sees a single or three phase load, it just wants to do it's specific job and this make everyone happy. Perhaps this competitor had one laying around and just wanted to re-coupe some of their investment from another job. Obviously it satisfies the letter of the code.


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## John Valdes (May 17, 2007)

No problem. Just extra expense for three pole. However, If 3 pole was all I had I would use it in a heartbeat.


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## frank (Feb 6, 2007)

No problem this end also. Just seems such a waste. But otherwise - if it's all you have to hand and you don't care who follows you to make a joke at your expense - why not?


Frank


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## beasley (Oct 18, 2009)

If you have a single phase 120/240 or 120/208 system, you would have to go by the manufacturer's specifications written on the panel. All Cb's that are acceptable are listed on the enclosure. No one should install a 3p cb in a single phase panel. Please note this is an improper installation. 3p cb's are to be used only for 3 ph systems, not single phase. Note, that one 3 pole cb is made (for special applications) in single phase systems ... i.e -.these are for switched neutrals only. Be advised that the manufactures instruction supperceed the NEC (as they are UL listed) for the application by the manufacturers design. My opinion is no 3p cb's in single ph electrical systems.


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## RIVETER (Sep 26, 2009)

faber307 said:


> Competition of mine put in a 3 pole breaker for a single phase load (the pedestal job)
> Now the customer is asking me if that is legal?
> Any long term repercussions of this?
> 
> ...


Approved...or not...for the purpose comes to mind.


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## idontknow (Jul 18, 2009)

Mountain Electrician said:


> I've done it more than once over the years, but at the very least it's not real cost effective. I always put A on A and B on C, not that it matters, just the way I've always done it.


Do you check the voltage afterwards? If it's in a single phase panel, you're not going to get 208/240 volts unless the bussbars are swapped.


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## beasley (Oct 18, 2009)

idontknow said:


> Do you check the voltage afterwards? If it's in a single phase panel, you're not going to get 208/240 volts unless the bussbars are swapped.


What do you mean your not going to get 208/240 volts unless the buss bars are changed? These are two different service systems mentioned as examples, the more common 120/240 (delta & wye). But I'm curious about buss bars are swapped? I have mentioned looking @ the manufactures specs ... gives V/A/max ckts., gives cb's & grnding requirements Keep in mind no panel (universal or not) may accept interchangeable Cb's, unless they are listed (by the manufacturer) for use in other panels! Whether they fit or are altered to fit. Always check with the AHJ in your area for complete clarification of code issues!


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## Magnettica (Jan 23, 2007)

I would install the 3-pole if it's all I had but then I would return with the right breaker.


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## McClary’s Electrical (Feb 21, 2009)

beasley said:


> What do you mean your not going to get 208/240 volts unless the buss bars are changed? These are two different service systems mentioned as examples, the more common 120/240 (delta & wye). But I'm curious about buss bars are swapped? I have mentioned looking @ the manufactures specs ... gives V/A/max ckts., gives cb's & grnding requirements Keep in mind no panel (universal or not) may accept interchangeable Cb's, unless they are listed (by the manufacturer) for use in other panels! Whether they fit or are altered to fit. Always check with the AHJ in your area for complete clarification of code issues!


 

What he's trying to say is that if this breaker is in a single phase panel, and he lands his wires where he said, they will both be on "a" phase, thus,like he said, no 240 volt


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## idontknow (Jul 18, 2009)

mcclary's electrical said:


> What he's trying to say is that if this breaker is in a single phase panel, and he lands his wires where he said, they will both be on "a" phase, thus,like he said, no 240 volt


This is 1/3 of what I was saying. Another 1/3 of what I mentioned is: the ability of some panels to unbolt the breaker "fingers" from the main buss bar and swap them. Therefore it would rearrange the A-B-A-B-A-B to A-B-B-A-A-B. The last 1/3 is: a single phase panel served from a wye 3 phase panel. It would have 208 between the two hot legs.

Clear as mud huh.


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## McClary’s Electrical (Feb 21, 2009)

idontknow said:


> This is 1/3 of what I was saying. Another 1/3 of what I mentioned is: the ability of some panels to unbolt the breaker "fingers" from the main buss bar and swap them. Therefore it would rearrange the A-B-A-B-A-B to A-B-B-A-A-B. The last 1/3 is: a single phase panel served from a wye 3 phase panel. It would have 208 between the two hot legs.
> 
> Clear as mud huh.


 

Whywould you do all that instead of landing it on "b" phase?


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## idontknow (Jul 18, 2009)

mcclary's electrical said:


> Whywould you do all that instead of landing it on "b" phase?





Mountain Electrician said:


> snip... I always put A on A and B on C, not that it matters, just the way I've always done it.


I've never had to do it, though I've seen some rearranged buss fingers on a panel at a school once. There was a huge permanent maker description of what was flip flopped on the inside of the dead front.


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## beasley (Oct 18, 2009)

*Response*



mcclary's electrical said:


> What he's trying to say is that if this breaker is in a single phase panel, and he lands his wires where he said, they will both be on "a" phase, thus,like he said, no 240 volt


There should be no issue about buss design if you install breakers that belong in 1ph panels. Because a 3p 3ph cb fits dosen't mean it can be installed in a 1ph panel. In fact 95% of the electrical inspectors would not accept this type of installation. NEC even says "designed for the purpose" (fact).


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## idontknow (Jul 18, 2009)

beasley said:


> There should be no issue about buss design if you install breakers that belong in 1ph panels. Because a 3p 3ph cb fits dosen't mean it can be installed in a 1ph panel. In fact 95% of the electrical inspectors would not accept this type of installation. NEC even says "designed for the purpose" (fact).


Do you have a reference for your 95% claim? You noted it as a fact, twice. 

Code also states, "By special permission, the authority having jurisdiction may waive specific requirements in this code or permit alternate methods where it is assured that equivalent objectives can be achieved by establishing and maintaining effective safety."

Technically an inspector could waive that requirement as the main objective has been met and safety maintained.

But please, don't let that distract you from the first question I asked.


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## leland (Dec 28, 2007)

What is this 'AHJ' 'Inspector' thing you speak of?:jester:

Absolutely. If I need to get paid- done. Not sure about the 'A'- 'C' thing though.


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## McClary’s Electrical (Feb 21, 2009)

beasley said:


> There should be no issue about buss design if you install breakers that belong in 1ph panels. Because a 3p 3ph cb fits dosen't mean it can be installed in a 1ph panel. In fact 95% of the electrical inspectors would not accept this type of installation. NEC even says "designed for the purpose" (fact).


 

care to back that up?


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## MF Dagger (Dec 24, 2007)

95% of all statistics are false.


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