what size of cable will i need for pizza oven, 3 Phase MCB?

[kevin1234]

18500 watts Pizza Oven, 415volts, what size of cable would i need for this and 3 Phase MCB??

Thanks

 

[Lectrician]

Whats the length of run?
Whats the installation method (clipped direct, on tray, in PVC trunk, in a wall etc).
What cable type are you using?

 

[kevin1234]

its about 40metres, PVC Cable and its in trunking and parts behind a wall?

 

[RF Lighting]

As this is a commercial installation, you need to engage the services of a commercial electrician to properly design the installation for you.

This is not the sort of thing which can be guessed at on a DIY website.

 

[kevin1234]

i know i understand that, but i am only enquirying i aint planning on doing anything

Can anyone help please?

 

[oharaf]

By my Calcs., and don't take it as read, for 3phase you would need

4mm SWA and a 32A MCB

 

[kevin1234]

why 4mm cable? how do you work out the cable size? do you base it on the MCB size, or the current the circuit pulls?

 

[oharaf]

You first need to calc tha current per phase

so 18500/230 = 80.4

80.4/3 = 26.8A

The Design Current is therefore 26.8A

So MCB is 32A

Assuming 1 cable and ambient temp of 30 and no insulation

Then cable(SWA) from tables is 4mm Voltage drop is 10.7 volts <5%


Anyone can check this I'm not betting my life on it

 

[kevin1234]

You first need to calc tha current per phase

so 18500/230 = 80.4

80.4/3 = 26.8A

The Design Current is therefore 26.8A

So MCB is 32A

Assuming 1 cable and ambient temp of 30 and no insulation

Then cable(SWA) from tables is 4mm Voltage drop is 10.7 volts <5%


Anyone can check this I'm not betting my life on it

So do you get the cable size from the Size of the MCB, or the Design current the actual circuit is pulling?

 

[sparkyspike]

You first need to calc tha current per phase

so 18500/230 = 80.4

80.4/3 = 26.8A

The Design Current is therefore 26.8A

 

[oharaf]

Not very well worded Sparkyspike

the oven is 18500W

so 18500/230 = 80.4A

3 Phases at 230V so

80.4 / 3 = 26.8A The circuit needs to be able to handle at least this.

Next nearest MCB is 32A so The cable needs to be able to handle 32A so selecting SWA 4mm should suffice.

But need to check V.Drop by calc this less than 5% assuming no insulation or grouping factors to consider

So 4mm SWA should suffice on a 32A Breaker!!!


Any better????

 

[RF Lighting]

I wonder what the ambient temperature will be in presumably a commercial kitchen, or lots of other factors...

 

[kevin1234]

Not very well worded Sparkyspike

the oven is 18500W

so 18500/230 = 80.4A

3 Phases at 230V so

80.4 / 3 = 26.8A The circuit needs to be able to handle at least this.

Next nearest MCB is 32A so The cable needs to be able to handle 32A so selecting SWA 4mm should suffice.

But need to check V.Drop by calc this less than 5% assuming no insulation or grouping factors to consider

So 4mm SWA should suffice on a 32A Breaker!!!


Any better????

Ye, that sounds good, but im wondering what it would be for PVC twin and earth?

 

[RF Lighting]

How could you use T&E for three phase?

You're two wires short for a start....

 

[ColJack]

18500 / &#8730;3 = 10680W per phase..

10680 / 230 = 46A per phase..

TLC recomends 10mm for a 20M run of 4C PVC SWA.. clipped direct