never done one before

**opm electrical** · 10-03-2010

i normally just do domestic stuff but my mate asked me to stick a cable and plug on a three phase motor in his factory but i havent done anything with motors since college and even then i didnt pay a great deal of attention, but i thought id have a crack anyway
its a 2.5 kw motor,
what sort of cable should i use and do i connect in star or delta and will type c 16a mcbs be enough

**Amp David** · 10-03-2010

I worked it out as 5.33 amps, without any consideration for power factor.

**DurhamSparky** · 10-03-2010

use 5 core flex cable!! yeah 16a will suffice!

not sure about the correct terminations inside the motor normally its just L1 L2 L3....! i used to just follow the test leads on a phase meter!!! quite funny when it goes wrong direction!!

simples!!

**opm electrical** · 10-03-2010

so a length of 2.5, 5 core flex should cover it then.

will there be a separate terminal for the neutral

**DurhamSparky** · 10-03-2010

yes there should be!!

mind you all my 3 phase experience was on royal navy vessels were both earth and neutral were non existant!!

seriously!!

**bugsy** · 10-03-2010

Before you rush out and buy the cable and plug you should determine the requirements, is it three phase or three phase and n also what socket are you going to plug into.
Terminations will be marked L1.L2.L3 , N if it requires N and Earth

**gaffer** · 10-03-2010

Use some SY bit more robust IMHO.

**benji** · 10-03-2010

neutral ? what neutral

yours benji

**Hawk81** · 10-03-2010

4 core cable needed not 5. No neutral at a 3 phase motor. Wire it in star. On that size of motor it would only be wired in delta if it has a variable speed drive was use to run this motor. I would use a 4 core sy and make sure to earth the steel braid at 1 end at least. A 10amp tripple pole mcb will do this well. If the motor goes the wrong direction just swap 2 of the phases around.

Originally Posted by bugsy

Before you rush out and buy the cable and plug you should determine the requirements, is it three phase or three phase and n also what socket are you going to plug into.
Terminations will be marked L1.L2.L3 , N if it requires N and Earth

Most motors do not come marked L1 L2 L3. They come marked U1 U2 U3. and on the other side V1 V2 V3. Only ever seen a single phase motor that required a neutral.

**Notsosmart** · 10-03-2010

Originally Posted by bugsy

Before you rush out and buy the cable and plug you should determine the requirements, is it three phase or three phase and n also what socket are you going to plug into.
Terminations will be marked L1.L2.L3 , N if it requires N and Earth

You hould be very careful in answering questions posed on this forum, if you do not know the correct response 100% then I believe you should not be replying.

Originally Posted by Hawk81

4 core cable needed not 5. No neutral at a 3 phase motor. Wire it in star. On that size of motor it would only be wired in delta if it has a variable speed drive was use to run this motor. I would use a 4 core sy and make sure to earth the steel braid at 1 end at least. A 10amp tripple pole mcb will do this well. If the motor goes the wrong direction just swap 2 of the phases around.

Most motors do not come marked L1 L2 L3. They come marked U1 U2 U3. and on the other side V1 V2 V3. Only ever seen a single phase motor that required a neutral.

Agree completely Hawk.