new supply

[maguire]

Hi all
What is the prescibed method of taking a supply from a tri phase CU if no spare ways are available. Can we without compromising the regs take from one phase at the Main switch. a discussion at work,
Mac

 

[electronicsuk]

You certainly can't take an unprotected feed from the main switch directly to a final circuit. Whatever you do would either involve installing a larger distribution board, or another one side-by-side fed from one or all three of the incoming phases and neutral.

 

[maguire]

Cheers Matthew my thoughts exactly, The other side said it would be ok to FCU then to the final circuit I argued every thing from the CU was the final circuit still, this was guys from a whirlpool bath company who wanted a quick in and out job I got my way though and they waited till it was done my way or rather to the regs
Mac

 

[electronicsuk]

Cheers Matthew my thoughts exactly, The other side said it would be ok to FCU then to the final circuit I argued every thing from the CU was the final circuit still, this was guys from a whirlpool bath company who wanted a quick in and out job I got my way though and they waited till it was done my way or rather to the regs
Mac

Sounds like you did the right thing. If the submain feeding the 3ph DB had been relatively small and rated to 32A or less then an FCU probably would have sufficed, despite not being the ideal setup. Anything larger than that and you'd need to install a new/extra DB, as a BS1363 FCU isn't designed to be used on a circuit with a protective device >32A.