motor disconnect

[apj]

greetings again.

I would like to ask another question while I have your attention. I am installing wiring for a large 3 pnase drill press in a residential shop. My question is what determines whether the machine gets a fused disconnect or non-fused? Is the disconnect by the machine just for safety to turn off in an emergency, or does it have to have fuses in it if there is no built-in overload on the motor or in the machine (e.g. motor starter)? Thanks again.

 

[bphgravity]

Re: motor disconnect

Not all disconnecting means are overcurrent devices and not all overcurrent devices provide a disconnecting means, however, most equipment and appliances require both so many manufacturer's incorporate them into one component like a breaker.

So to answer your question, it depends on where you need / wish to have these two components. You need to provide overcurrent protection for the motor (possibly overload) and for the circuit conductors and you need a means to disconnect the load from the source.

It is possible to provide overcurrent protection at the source of the branch ciruit and only provide a disconnecting menas at the equipment, or you may wish / need to provide both at the equipment together. Usually the choice is a design consideration.

 

[apj]

Re: motor disconnect

I am sorry I did not mention that this circuit will come from a breaker box and have o/c protection from a breaker. I am interpreting the code to say that all motors with the exceptions in 430-32D must have separate overload protection. Any help will be appreciated. Thanks.