isolator for main ccu

[cryoservice1]

hi there

am i just being blonde?

worked out the maximum demand for an install to be 630A,

it 3 phase for a hotel,

i have sub mains throughout to five other boards,

now do i need a main isolator to cover this value or do i need to split the 630A between the three phases and go for an isolator to cover the 210A?

ie. either a 800A or 250A

your comment would be appreciated.

thank you

 

[bugsy]

Isolator rating will be governed by the cutouts ( DNO fuses ) , the load will taken over the three phases

 

[Guest123]

As Bugsy said your loading would not be 630A per phase.....that 630 would be balanced out across the 3 phases. I would allow a 250A as a minimum maybe more depending again on the suppliers fusing.

 

[gaffer]

Over here when it becomes comercial the DNO sometimes asks for a switchfuse at the incomer.
Im asuming youve used diversity?
As previously said ,its spread across the three phases.