Commercial Equipment 3 Phase Query

[Devnet]

Hi,

I’m trying to buy/install a large commercial boiler which is 3 phase and I’m trying to understand the supply requirement to see if my existing 3 phase supply can run it. The unit requires approximately 70amps but what I’m getting mixed feedback on is if it’s 70amps per phase required or if that 70amps is split across the 3 phases so 23 odd amps per phase. Details of the specifications from manufacturers are below any advice appreciated.

Supply Voltage 380-400
Frequency 50-60
Kw 48
Power Cable 5 x 35mm2

 

[Fleeting]

With 400v you are just under 70A and 380v around 72A.

 

[Andy™]

70a per phase

 

[Devnet]

Thanks for the reply’s, I’ve basically got the Italian manufacturer saying it’s definitely approx 70 amps spread over three phases and not per phase, they use the below calculation. But British electricians state it’s per phase based on that information so I don’t know who to go with…and wonder if there is anything lost in translation for how the manufacture work out their kWs etc.

48 kW > 48.000 (W)/1,73x400(V) = 69 A

 

[Andy™]

that calculation is per phase...

 

[Devnet]

This is what I thought but apparently the manufacturer insists it’s spread over the phases and the same has been advised to many other units sold and setup by electricians to this and there’s never been any issues.

Issue I have is it will involve a 50 metre armoured cable wire run upgrade so I want to make sure it’s right but at the same time don’t want to have to spread considerable more than is needed to service it.

The big telling point is the advised 35mm2 supply cable in the specification. I wasn’t sure if it’s max would be 48kW when it’s first turned on and then it winds down as it heats up but suppose wouldn’t make a difference.