RCD Rating

[coatesykid]

Can someone please explain to me how the Rating of RCD work because I've read on different forums that you can not exceed the rating of the RCD ie 63A or 80A if that's the case why do C.U like 10 way dual RCD, have a total MCB rating of 218 A if all MCB was used and only 143 total A for the RCD's, surly maximum demand comes into play.

 

[Knobhead]

Post a link then, we’re intrigued.

 

[coatesykid]

cant remember which forum it was

 

[coatesykid]

Thanks for all the replies, I'm off to go post a new thread

 

[Knobhead]

Put a first class stamp on it. We can't wait.

 

[ackbarthestar]

Can someone please explain to me how the Rating of RCD work because I've read on different forums that you can not exceed the rating of the RCD ie 63A or 80A if that's the case why do C.U like 10 way dual RCD, have a total MCB rating of 218 A if all MCB was used and only 143 total A for the RCD's, surly maximum demand comes into play.

In the context of the question, you could think of an RCD as a main switch. Its rating of 63 or 80A is the maximum current that can flow via phase and neutral. The mA rating that follows is related to leakage or fault current that bypass the RCD.

As far as the maximum demand goes. No domestic installation runs at the maximum rating of its combined protective devices.

 

[wildgoose]

If you wanted to do a really quick calc for max demand, without consulting the diversity regulations, then add up all the breaker ratings and then multiply this summed value by 0.4

That value won't be too far off but this is an approximation AND NOT the recognized method for doing it.

 

[Engineer54]

If you wanted to do a really quick calc for max demand, without consulting the diversity regulations, then add up all the breaker ratings and then multiply this summed value by 0.4

That value won't be too far off but this is an approximation AND NOT the recognized method for doing it.

It's a dammed sight more accurate than the recognised method of doing things!! ...lol!!
You'll only ever get an approximation, whatever method you use!!!!