RCD Amp rating. Diversity

[AndyPRK]

Say you had a dual RCD CU.


You had a 63A RCD fitted, and for the sake of argument you had 3x32A MCB's connected to that RCD.

Say a cooker, hob and ring.

Main fuse probably 60A.

I assume that is ok? As in practice the ring isn't going to be drawing much current and the cookers not at maxiumum load.

Thank you

 

[MalcofArabia]

An old rule of thumb that DNO sparks use for diversity is add up all your protection devices and multiply that by 0.4. That will give you a rough guide to how much loading you will use. It's not a definate design formula but as a guide it's pretty good

The 3 x 32amps sound fine. If you think that a cooker range with a combined hob/oven in one unit could be fitted on a 32amp protection device on it's own as they often are. So I would think you are ok there

 

[AndyPRK]

thanks for that tip.

That would be 38A then.

 

[MalcofArabia]

You wouldn't normally do sub divisions of the installation like that. But as I said it's a good rule of thumb for an installation and you could class your 63amp RCD as a sub division so 38amps seems about right.