circuit breakers

[marcus1]

can some one point me in the right direction . question: can a 3 phase breaker be the disconnect means for a single phase load can't find in code

 

[charlie b]

It's not in the code. That is usually enough of a reason to say that it is allowed. But why would anyone want to?

Welcome to the forum.

 

[yursparky]

Question is: Is it listed to be used as a single phase disconnect?

 

[jim dungar]

can some one point me in the right direction . question: can a 3 phase breaker be the disconnect means for a single phase load can't find in code

A UL 489 listed breaker has been tested for 1, 2, and 3 pole operation.

 

[bobsherwood]

circuit breaker

circuit breaker

I don't have my 2008 code book here but, I think it's 210.. 13, 14?? somewhere in there. It now says that multi phase circuits (a, b, c phase with one neutral) all ungrounded conductors must be turned off by the same device. Not in those words though.. I don't like or agree with this change but, it's there. So, it seems that a 3 pole breaker will be the ONLY way to protect the hot's on the same neutral. I hope this make some sense??

 

[enosez]

Correct me if I'm wrong, but are you asking if a three pole breaker can be wired using only one of its legs.

Why would you want to use up the space of a three pole breaker int he panel and leave the potential for someone to come along and use the other two legs

 

[iwire]

Question is: Is it listed to be used as a single phase disconnect?

Does it have to be?

A two or three pole breaker will work fine with a only some of the poles used.

Unusual, yes, violation, no.

 

[Dennis Alwon]

but are you asking if a three pole breaker can be wired using only one of its legs.

Maybe, but maybe not-- a single phase load can be a 208 load-- or whatever the voltage is at the panel, ie. using two phases of the 3 phase load.

It now says that multi phase circuits (a, b, c phase with one neutral) all ungrounded conductors must be turned off by the same device. Not in those words though.. So, it seems that a 3 pole breaker will be the ONLY way to protect the hot's on the same neutral. I hope this make some sense??

Yes, a 3 pole breaker or listed breaker ties would be the only way to do that but the OP really isn't asking that question. IMO

I don't believe there are any listed 3 pole breaker ties anyway....

 

[Pierre C Belarge]

It's not in the code. That is usually enough of a reason to say that it is allowed. But why would anyone want to?

Welcome to the forum.

An electrician from the company is sent to a job 100 miles from the shop to troubleshoot a dead circuit. The EC services this company a lot, they have other buildings, all in the local area the shop usually services. The electrician finds a bad breaker for the circuit, it is not the brand of panels they usually service, so he goes to the local supply house and all they have available is a 3-phase CBer. He calls the office, they tell him to install it and head back to the shop, as he is being sent out the next day to a location that will be 150 miles south of the location he is at today.
That is one reason.

 

[billsnuff]

A UL 489 listed breaker has been tested for 1, 2, and 3 pole operation.

but wouldn't you loose all three if one faulted vs. three singles, you would loose one, but have to shut off all three for repair?

edit spelling

 

[Dennis Alwon]

but wouldn't you loose all three if one faulted vs. three singles, you would loose one, but have to shut off all three for repair?
edit spelling

Yes you would lose all 3 circuits but this is not what the op has. The OP is asking if he had a single phase circuit---ie, one ot two hot conductors---can he connect it to a 3 pole breaker.

As of 2008 here is the rule

210.4 Multiwire Branch Circuits.
(A) General. Branch circuits recognized by this article shall be permitted as multiwire circuits. A multiwire circuit shall be permitted to be considered as multiple circuits. All conductors of a multiwire branch circuit shall originate from the same panelboard or similar distribution equipment.
FPN: A 3-phase, 4-wire, wye-connected power system used to supply power to nonlinear loads may necessitate that the power system design allow for the possibility of high harmonic currents on the neutral conductor.
(B) Disconnecting Means. Each multiwire branch circuit shall be provided with a means that will simultaneously disconnect all ungrounded conductors at the point where the branch circuit originates.
(C) Line-to-Neutral Loads. Multiwire branch circuits shall supply only line-to-neutral loads.
Exception No. 1: A multiwire branch circuit that supplies only one utilization equipment.
Exception No. 2: Where all ungrounded conductors of the multiwire branch circuit are opened simultaneously by the branch-circuit overcurrent device.
FPN: See 300.13(B) for continuity of grounded conductor on multiwire circuits.
(D) Grouping. The ungrounded and grounded conductors of each multiwire branch circuit shall be grouped by wire ties or similar means in at least one location within the panelboard or other point of origination.
Exception: The requirement for grouping shall not apply if the circuit enters from a cable or raceway unique to the circuit that makes the grouping obvious.

 

[bobsherwood]

circuit breaker

circuit breaker

Bill,
that is the problem. I work at Southern Methodist University. Imagine how many lights on a 277v. circuit would go off if I needed to turn off one "3 phase" breaker to work on one switch. I am sure this code is meant to protect workers from a loaded neutral but, ALL of my guys know about loaded neutrals. We also know NOT to open such neutrals. I think it's a bad new code.