3 phase 63A

[dave-gardiner]

Hi
we have a 3 phase 63A isolator.
i have been asked to supply from this 3 x single phase 63A sockets. I have said this cannot be done because the neutral is only sized for the 63A supply. But now i am questioning myself. Help please

 

[Guest 004]

3 x 20 Amp supplies would be ok. Certainly not 3 x 63

 

[plugsandsparks]

sorry must disagree, as the op states he wants 3 x 63A Single phase supplies. Fully loaded you can have a current of 180 Amps flowing down the neutral. 3 phase machines are different, because any unbalanced currents just flow down the neutral.

I thought three phase was supposed to be 120 degrees out of phase with each other. So the neutral gets a rest. 180amps.... does not work like that.

 

[Plonker 3]

Here is how to work out the current in the neutral, thanks to tel

SQRT I²A + I²B + I²C - (IA x IB) - (IB x IC) - (IC x IA)

 

[MDJ]

Now look you lot lol, imagine the Switch fuse or Isolator the OP mentioned was a distribution board yes? and you run 3 single phase supplies from the Distribution board to seperate switch fuses or Isolators? would you need to rip out the main neutral and install one 3 times larger than the phase cables? think about it.

 

[Guest 004]

You can have inductive load, capactive loads, and resitive loads each all on one phase each. Which will pull well in excess 63 Amps fully loaded.

 

[dave-gardiner]

So can i or not

 

[Plonker 3]

But the 3 phases are out of sync by 120 degrees each.

 

[thebigcheese]

It would be absolutely fine to have Three 63A Single phase supplies (one on each phase) run from a 63A Three Phase supply as the Neutral currents would cancel out (unless you had harmonics etc)...amazed at the ignorance of basic electrical theory on here.

Hopw else do you think something like this would work... Rubber Box - Type 270 Power Distro Box

 

[Plonker 3]

Now look you lot lol, imagine the Switch fuse or Isolator the OP mentioned was a distribution board yes? and you run 3 single phase supplies from the Distribution board to seperate switch fuses or Isolators? would you need to rip out the main neutral and install one 3 times larger than the phase cables? think about it.

Obviously

You can have inductive load, capactive loads, and resitive loads each all on one phase each. Which will pull well in excess 63 Amps fully loaded.

:mad2:

 

[dave-gardiner]

Sorry been doing elec maintenance for far too long and forgot the basics

 

[MDJ]

Never seen an armoured cable with 3 cores which are 10mm2 and one which is 30mm2 LMAO

 

[Plonker 3]

It would be absolutely fine to have Three 63A Single phase supplies (one on each phase) run from a 63A Three Phase supply as the Neutral currents would cancel out (unless you had harmonics etc)...amazed at the ignorance of basic electrical theory on here.

Hopw else do you think something like this would work... Rubber Box - Type 270 Power Distro Box

You have to put a bigger neutral in of course :earmuffs:

- - - Updated - - -

Never seen an armoured cable with 3 cores which are 10mm2 and one which is 30mm2 LMAO

Thats cos you cant get 30mm cable silly

 

[Guest 004]

^LOL
OK so as long we can cancel out the neutrals we can have as much load as we want, and nothing will ever flow down the neutral, and it will never burn out, and we never get an arcing neutral, that will never roam, and never cause a fire.

 

[Plonker 3]

No, we are saying the current in the neutral will never exceed the maximum current carrying capicity of L1, L2 or L3 as longt as it is installed correctly.

Why do you think we always calculate the size of L1, L2 or L3 and not the neutral?

 

[Silly Sausage]

Can't resist any longer!

3 single phase 15kW heaters wired with 3P plugs on Brown, plugged into these three sockets..............