The idea that you are considering using a circuit breaker terminal as a neutral leaves me suspicious of your understanding.

 

The breaker would treat it as a short circuit and trip everytime voltage was pushed through the terminals(I did that with my Hadco landscape PSU earlier). I see what you mean, Just a theory, in fact I tested it on a much smaller scale earlier . But is it still possible to use this 3 phase breaker as if it were a single phase disconnect?

 

Is 120volts available at the 600 volt service? Not too likely.

 

The service is 120v coming from the street. And all I want to do is hook up both phases from that to the breaker if that makes sense and run it to the distro panel

 

That makes no sense. Show the installation.

 

See if this helps, just a three pole breaker in place of a two pole

 

Does the panel have a neutral bus bar off to the side? A 3 phase panel designed for wye or star 3 phase systems will have that.

No problem using the 3 phase panel for single phase feeds or services provided it has the neutral bus bar (either present or sold separately).

A small number of systems notably systems with a generator hookup may use a switched neutral in the master disconnect switch or breaker. I personally don't like switched neutrals since that is one more component that could go wrong, and a broken neutral causes all kinds of problems.

 

No, I'm just using this box as a single phase disconnects, and I'd just pass the neutral through it back to the service transformer

 

Not sure I 100% understand what you are trying to accomplish here?

Is this just for a single 3-wire 120/240V branch circuit? What is it being fed from? Is there going to be another breaker ahead of it suitably sized for the load and conductor size you intend to use?

As others have already mentioned, the neutral should not be switched/fused.

A 600A breaker is certainly unlikely to trip under any fault condition you'd ever come across in a typical household installation.

 

Yes just consumer 120 a and B phases, I need a cutoff switch for the mainframe in the basement.