Which Circuit Breaker to Use at 415 VAC?

The one with a rating to suit the voltage and current. Ask at your local supllier.

If your supply is a 240/415VAC transformer you should be using 2 pole. Phase to Phase connection for 415VAC

Elementary My Dear Watson!

415/240 Means 3 phases-4 wires:

R>N,Y>N,B>N are 3 different phases ditributing to say 3 different floors--each using 240V AC 1 phase(+Neutral).

You (almost) never isolate the Neutral -barely 10V max. likely.

So you always use 1 pole circuit breakers - to isolate 240VAC single phase Circuits.

Sorry but was the question not about a 415V supply rather than 240V?

If you have a 415V electric motor the supply will be a 3 phase supply, there will be four wires -

a N (which you do not need to break, but can as long as you keep an earth connected) and the

3 live 240V phases [1/2/3 or R/Y/B or Brn./Blk./Grey in UK now!!]: so you would need a 3 pole breaker minimum, appropriately rated.

Phase to Phase on a 240/415 system (known as split phase or 2 phase ) is about 440V, This used to be common on remote farms but not seen so much now in the UK. This would be a Two Pole Breaker.

A 3 phase supply will be 380V with a 3 x 220V & 400V with 3 x 230V.

Great Forum, I will register soon, ta.

"Phase to Phase on a 240/415 system (known as split phase or 2 phase ) is about 440V, This used to be common on remote farms but not seen so much now in the UK. This would be a Two Pole Breaker."

The phase to phase voltage on system that has 240 V to neutral or ground is 415 V.

As the Guest stated in the original post.

"Hi, i want to clear that can we use a single pole or double pole circuit breaker for the 415 VAC. Please clear"

Since the voltage is 415 V the supply must be at least a 2 phase and is most probably a 3 phase system. Regardless of what the load is each phase must have a circuit breaker installed. If you don't then you will end up only protecting 1 phase and when the breaker is tripped there will still be power downstream of the panel on the other phases.

Whether or not you can use multiple separate circuit breakers or proper multi phase breakers depends on what equipment is being protected. If you are supplying a single load then you must install a single multi phase circuit breaker. This is necessary as some three phase equipment can be seriously damaged if power is lost on a single phase while the remaining phases still have power. It can also be dangerous. A multi phase breaker will disconnect all the phases if any one of them goes outside the operating conditions.

If you are supplying multiple 240 V loads downstream and there is nothing that uses all three phases then you can use three separate circuit breakers. However, keep in mind, if at some time in the future you install a three phase load, you will need to add a three phase circuit breaker just for that load.

If your load is single phase use single phase breaker,if your load is 2-phase use 2-phase breaker....or 3-phase load use 3-phase breaker.

Here's a lead for you to follow-up on:

Dan McManus, Senior Sales Engineer for Eaton (Cutler-Hammer), email danielmmcmanus@eaton.com.

Dan can qualify your application and suggest a solution.

Please define your load to which you want to supply. Is it single phase load or three phase load. Incase you are trying to tap of 240Vac from a three phase line for a 240Vac load, then use single pole breaker on active line. Otherwies, if it is a three phase load then you may use a three phase breaker, three pole.

Futhremore, the breaker current rating should be of some good allowances to the required current of your load. So that if the load draws to much current (due to shorts, the breaker will trip protecting your load, personel life and fire hazards) beyond its rated opeartional current, the breaker should trip/switch off.

Besides that, others have contributed good advice, but once again, define the rated voltage and current required for your load.

Regards,

Ron