CU Capacity

[Andypease1]

I have a large house with two CU units about 5 years old professional intallation. The lighting one has a red 100a Switch disconnector (apart from lighting in contains a 20a RCBO for the Front gates and pond and a 45a RCBO for the shower). The other used for power etc has a 100a rccb. Is there a limit to the total value of the MCB and RCBO's contained in each CU.

Thank you

Andy

 

[Taylortwocities]

Yes, but that really refers to the total DEMAND (assumed load).

This is calculated using a technique called diversity - it assumes that you will never have all of your sockets etc fully loaded 100% at any one time.

The total maximum DEMAND is checked against the max current for the supply that you have been provided with.

It is not a case of adding up the trip current of every MCB in your CU and trying to keep it under 100A. If the electricity supply companies did that we would need another 100 nuclear power stations!