I have an enclosure with a 3 pole breaker but my house only has 2 hot wires, can I use the circuit breaker safely without any harm?

 

It will work well using the 3 pole (triple wide triple) breaker for a 2 hot plus neutral 120/240 volt circuit or even a one hot plus neutral 120 volt circuit.

Most likely the enclosure was or is for a 3 phase electrical system but you can use the phases individually (provided you have a neutral) or two at a time (for 240 or 208 volts depending on the system).

The disadvantage of using one 3 pole breaker instead of 3 single pole breakers is that if one circuit should trip its breaker, up to 2 other circuits (sharing the breaker set) will be flipped off too.

Be sure you have a neutral in the box before connecting up a 120 volt circuit. You may not use ground in lieu of neutral. Also measure the voltage between the chosen breaker terminal and neutral before connecting it up. In some 3 phase systems (240 volt delta) one pole will measure 208 volts to neutral and you never want to use that pole all by itself.

 

Where are you wanting to use the 3 pole breaker, will this be your main service disconnect? Does the enclosure have a neutral bar?

 

Yes, I want to use it as a main service disconnect. Yes there is a neutral bar.

 

Using a 3 phase panel will also have 1/3 of the panel spaces dead.

 

I forgot to ask in my last post, when connecting, should I connect the neutral first?

 

All work should be done with the panel off.

Many like to cut-in a panel doing grounds first, neutrals and then the hots out of practice.

 

Is it service entrance rated? It needs to be.

It shouldn't make any difference because the meter should be pulled or the service disconnected by the power company and everything should be dead.

 

Thank you everyone for your help. One last question. Is there a distance limit from the service entrance? Does it have to be within 5 feet or 10 feet?

 

The NEC requires the unfused conductors to be "as short as practical". No actual distance is specified. This is up to the inspector.