CIRCUIT BREAKER

No! 3 phases needs 3 poles. A 2 pole breaker will leave one phase energized.

Huh???

Not if you are feeding a single phase load. Of course it's OK to feed a single phase load from a 3 phase supply, how else would you do that?

NO! You will probably get that from every one. However just FYI... Use this as a simple explaination as to why: ( If you want ). The term three phase represents the three different source angles of 110 Volts AC. Typical would be a delta application. That is three phase with no neutral. The 'Y' should you run into it would be three phase and the Y leg is the neutrl used for 100 volt , ( 1 hot leg and 1 neutral to get 110Vac to be used with ancillary equipment that could only use 110Vac). A 2 pole breaker is in effect two single pole breakers tied by the metal bar on the switch. That is so if one leg draws too much it will mechanically trip the other and cut all power to the equipment. With that in mind a three pole breaker is or are three singles tied mechanically to trip for the aforementioned reason. You will notice that on the breaker panel the two or single or the three pole breaker does not get its power from the same bus bar as its next door breaker. Every third 'pole', or bus contact is common to the next third one. Or in the case of a two pole panel every second pole is tied to the next second. So in short if your panel is a three phase panel, you need a three pole breaker each leg of witch is using a different phase angle. You could of course use three single pole breakers tied mechnically but God and every electrician including all insurance companies will hate you forever. CSA/UL is the way to go.! The ASHMAN

Good comment by Ashman. Big No; safety will be at risk.

I agree with you Ashman. I am not an Electrical Engineer but I am a construction Inspector. We use 3 phase electrical source and yet we have some 3-phase and/or single-phase sub-panels that are tapped from the main panel. Of course load distribution is calculated by the Electrical Engineer for safety and arrangement.

Hey! Thanks Willyap06! I am sure he regrets asking. But what I find funny is a "yes answer". And no offense to those who posted a yes, but first If this guy was actually installing a panel or had the capability to do so himself, he wouldn't have asked his original question. And two; Could those people that say yes possibly record on video the look on the Electrical Inspector's face when he sees it. Submit to: America's Funniest Videos.... :-) The Ashman!

Initial reaction was an emphatic NO!

Then I started thinking, the 110V 3 phase is not a common 3 phase voltage in North America.

Are you taking 2 phases of a 3 phase neutral grounded system to provide 120 / 208 volts? If so, the neutral is not broken and you use a 2 pole breaker.

There are a few systems that use 120 / 208, 3 phase, but it is rare, and requires a 3 pole breaker. Appliances that are 120 / 240 volts are sometimes plated as 120/208/240, but things like stoves don't run as hot on the 208, but elements last longer :)

A possible response is yes you can use a double-pole breaker on a three-phase supply but there are conditions to that answer, and the answer itself is purely "academic" in that the need to derive power with a double-pole breaker on a three-phase system begs the question "what for"?

Then after reading the responses I must say by the nature of the question the original poster may not be as well versed in the electrical field as some of the responders. One of the most common failures in design occurs when the engineer "solves" the wrong problem. In this case the way the question is posed, it is likely we are making that error here. Each responder defined the problem in his/her own way and proceeded to solve it. I risk doing the same with the following:

Given that there are a multiple of different voltages and (phased) systems available world wide, I make my first assumption and limit my response to be based on the US system of standard Utility voltages.

NOTE: Per the (US) National Electrical Code we use a "nominal" voltage designation when referring to voltages in general. Standard supply voltages are 120V (which will serve loads that are calling for 110V, 115V, 120V, 125V or 130V - or anything in between), 208V which will serve loads calling for 200V , 208V or sometimes 210V), 240V (which can be applied to loads requiring 210V, 220V, 230V or 250V).

!. From the system description of "110 V three phase supply" I assume we are talking about a 208y/120V 4-wire three-phase source (WYE configuration) where any of the three phases provide an identical voltage when referenced to a (grounded) neutral. This is a very common voltage system for small commercial and light industrial users. The use of the term "phase" implies an AC (as opposed to a DC) system. The correct shorthand for this is "208y". (The response above describing the "DELTA" would not be applicable here if standard (US) voltages were involved because with a DELTA system there are only 2 "legs" with 120V available and then only on a "special" DELTA systems. Theoretically you could produce a 110V three phase DELTA but it would be quite unique. 2. The question then asks "can we use a double pole breaker"

The answer is yes you can use a 2-pole breaker on a three phase supply.

Although the question has been answered - I doubt if the right one was asked and suspect the answer won't "solve" the real problem. In order to do that one would have to know:

What is the load to be served by the "double pole" breaker (in kVA or Amperes)?

What is the voltage required by the load? 208? 120? 120/208? (or something close ie 200,220,230,240 or 110, 115, 130)

What is the nature of the load? resisitive (heater, stove), inductive (transformer, motor, some really big heaters etc).

What size breaker are we trying to use to serve this load?

And finally what is the available capacity of the supply?

Answers to those questions might allow a reasonable - and possibly useful - solution, although odds are a few more questions will become apparent once the entire "problem" is defined.

Excellent!

Yes, if it fits the panel you're putting it in.

The long responses you've gotten appear to be from people who don't know much about the subject.

Please keep in mind that the voltage will be phase to phase and not phase to neutral. For example, in the USA, it's common to have a 120/208V, 3 ph panel whereby you get 120V from any phase to ground. A two pole breaker gives 208V.

Your comment is out of line.

O. K. -- I'll put it in line.

My response was out of line. I went back and read through the whole thread again and found that some of the short answers are also written by people who don't know much about the subject.

"Yes, if it fits the panel you're putting it in."

Your response is irresponsible and not supported with adequate assumptions or limitations.

You are assuming it is a lighting panel or something similar.

However, many control systems are in built up control panels or MCC construction.

The original question is also not well defined and leaves far too many variables, is it industrial, commercial, residential, application, country, what the load is that is to be attached (1 phase, 3 phase) etc.

All the answers were legitimate based on assumptions made by those who responded.

Glenn Wright, BSc, P.Eng

Hmmm . . . The original question was, "CAN WE USE A DOUBLE POLE CIRCUIT BREAKER IN 110 V 3 PHASE SUPPLY?"

The answer is, "yes."

Bill Willis, BSc, P.E.

"Although the question has been answered - I doubt if the right one was asked and suspect the answer won't "solve" the real problem."

I think that response from Wireman sums up everything that was important in this thread. It was a poorly constructed question to start off with, so the answers are never going to be worthwhile.

My personal assumption was that he had a 208Y120V 3 phase 4 wire system, and he wanted to tap off to feed a single phase 208V load and was asking if he could do that. I realize now that there are a myriad of different ways that ambiguous question could be interpreted, so I think the OP needs to re-craft the question before we waste any more time on it.

Just make sure it's an actual Circuit Breaker (UL 489), not a "Supplementary Protector (UL 1077). In a "Branch" application, the SP's have been known to fail "welded" shut, then catch on fire when re-energized - very commonly misused in equipment from outside the US.