Two pole circuit breakers

[czarstoo]

This seems like an eacy question, but I can't find a simple answer in the NEC.

1. Are the circuit breakers that are used to protect circuits such as residental ranges, dryers, hot water heaters, etc required to be two pole (factory connected) breakers or can two single pole breakers be used?

2. What should or must be done about the continued use of two single breakers in older, existing (not new) residences?

 

[charlie]

Re: Two pole circuit breakers

A two pole circuit breaker with handle ties or two single pole circuit breaker with handle ties is permitted to be used for these applications until the 2005 Code takes effect in your area. The 2005 Code will require a common trip circuit breaker to be used.

As far as the continued use of two single breakers in older, existing residences, that is totally up to the law in your area.

[ May 05, 2005, 02:52 PM: Message edited by: charlie ]

 

[milwaukeesteve]

Re: Two pole circuit breakers

I believe though, and I am doing this without the aid of a safety net, that 2 individual circuits that are present on the same yoke(device) must be tied together at the panel. In this case you would use 2 separate breakers, and 'tie' the handles together with an appropriate device.
An example of this would be to bring 2 circuits to a duplex receptacle, break the tab obviously, and plug in two separate loads. This application is rare but sometimes needed.

This is completely different from a circuit that needs both poles/phases to complete the circuit, like a dryer, oven, welder.

 

[milwaukeesteve]

Re: Two pole circuit breakers

That last reply was without the aid of either 2002 or 2005. I don't have them available right now. Hence, the safety net.

 

[charlie b]

Re: Two pole circuit breakers

m-steve: I'll grant you the safety net. But I believe the original question had to do with single-phase 240 volt loads. You are discussing two separate single-phase 120 volt loads that supply power to two separate devices that share a common yoke.

 

[milwaukeesteve]

Re: Two pole circuit breakers

Yeah, I know. I think what I was trying to say was that there are instances where a 'made' handle tie will still be used, but not for single phase 240V circuits. A breaker that supplies a single phase 249v circuit will be required, as stated previously, will require to be a single breaker with a common trip between poles, not relying on the handle.

I was racing out on my way to a meeting while writing that.

Thanks for being my safety net Charlie!

[ May 06, 2005, 01:13 AM: Message edited by: milwaukeesteve ]

 

[milwaukeesteve]

Re: Two pole circuit breakers

249V ??? Time to go to bed.

[ May 06, 2005, 01:14 AM: Message edited by: milwaukeesteve ]

 

[czarstoo]

Re: Two pole circuit breakers

It seems to me that the 240 volt circuits used for ranges, dryers and hot water heaters meet the criteria to be identified as multiwire branch circuits. Then, from NEC 2002, 210.4(C) exception 2, if they are multiwire branch circuits, all ungrounder conductors must be opened simultaneously.

 

[infinity]

Re: Two pole circuit breakers

czarstoo,

I don't have the 2002 NEC in front of me but are you saying that all multiwire branch circuits require a multipole CB?

 

[milwaukeesteve]

Re: Two pole circuit breakers

210.4(C) does not say that. It does say that MW branch circuits can only feed line to neutral loads (what we normally call multiwire branch circuits or a network), except in the following exceptions:
1) where the circuit supplies ONLY one utilization equipment and
2)where all ungrounded conductors of the circuit are opened simultaneously by the branch circuit overcurrent device.
For normal networks, it says nothing about it being a 2pole breaker.

Now in 2005, 24.20(B) states that the breakers of a MWBC may be individual breakers where feeding individual line to neutral loads.
210.4(B) States that where the MWBC feeds more than one device on a single yoke, a means shall be provided to disconnect simultaneously all the ungrounded conductors at the breaker.
210.4(C) states in the exception the same as above listed for 2002 about NON line to neutral loads and the breaker.

 

[necbuff]

Re: Two pole circuit breakers

Be careful.. Make sure your local juristiction does not have an amendment to this. The State of Tennessee does not permit two single pole OPD's unless the load has a grounded conductor. Straight line to line loads must have a two pole OPD.

 

[infinity]

Re: Two pole circuit breakers

I agree with you Steve that a MWBC supplying line to neutral loads does not require a multipole CB unless those loads are on the same yoke.

 

[kturner]

Re: Two pole circuit breakers

My understanding of the change to the 2005 NEC is that all exceptions that permit single pole breakers with handle ties remain. The only change is that the handle tie must now be "identified" rather than "approved".

 

[milwaukeesteve]

Re: Two pole circuit breakers

Thank you NECBUFF for being my safety net, again.
Yes, the individual State or Municipality rules may regulate this different than NEC, but that should be on the individual to realize that they still have to corallate the NEC with their local AHJ's before attempting anything without a net.

 

[charlie]

Re: Two pole circuit breakers

240.20(B) Circuit Breaker as Overcurrent Device. Circuit breakers shall open all ungrounded conductors of the circuit both manually and automatically unless otherwise permitted in 240.20(B)(1), (B)(2), and (B)(3).

This statement requires a common trip circuit breaker except as permitted by (1), (2), and (3).

(2) Grounded Single-Phase and 3-Wire dc Circuits. In grounded systems, individual single-pole circuit breakers with identified handle ties shall be permitted as the protection for each ungrounded conductor for line-to-line connected loads for single-phase circuits or 3-wire, direct-current circuits.

It looks like I am eating a little crow again. The range, water heater, dryer, baseboard heaters, etc. in a home will fall under (2) and will be permitted to be protected with a non-common trip circuit breaker with identified handle ties.

 

[kturner]

Re: Two pole circuit breakers

The idea being to prevent the use of nails, screws, or pieces of wire as handle ties and to require something that's "identified for the purpose".

 

[wwebb]

Re: Two pole circuit breakers

Excuse me, Charlie, but doesn't that exception only apply to DC circuits???????

 

[kturner]

Re: Two pole circuit breakers

240.20(B)(2) Grounded Single-Phase and 3-wire dc circuits.