17th edition CU

IanS · Jul 21, 2009

Would be grateful for comments on this one relating to a recently installed CU. It is a MK Sentry split load type. One group of circuits is protected by an 30 mA RCD rated at a current of 80A. Adding up the MCBs there are 112 amps worth on this one RCD.

My understanding (perhaps mistaken) is that this is incorrect. The maximum possible current should be less than 80A , no diversity. Would be grateful if anyone out there could comment, confirm or otherwise.

Thanks

Mark.W · Jul 21, 2009

How did you work out your 112A? I know you said you added your MCB's but how? Did you simply just add the MCB ratings?

IanS · Jul 21, 2009

Yes the 112A is the sum of all the MCBs on that RCD. No diversity

Yes the 112A is the sum of all the MCBs on that RCD. No diversity
32 sockets
32 cooker
32 shower
16 water heater

ICE · Jul 21, 2009

Hiya

What chance do you suppose that all of them circuits are going to be fully at the same time?

ICE

Risteard · Jul 21, 2009

And why aren't there lights on it? Lights shouldn't all be on one RCD, but split between the two.

IanS · Jul 21, 2009

Thanks for the comments.

I agree it is unlikely that all will be full on at the same time, but wondered if there was any clear guidelines for this situation.

Lights - I also agree but in this case it seems that both upstairs and downstairs have been wired through the other RCD.