RCD MAX DEMAND

[misha8904]

wHAT IS THE MAX DEMAND AN RCD CAN TAKE, IE: IF IT IS AN 80mAmp.
tHE REASON IS THAT I HAVE SEEN BOARDS WITH UP TO 140 aMPS ON THAT SIZE RCD, IS THAT SAFE?
WAYNE

 

[breezer]

caps lock stuck is it?

how do you know it was 140 A

just because total load (when added together) makes 140A does not mean 140A is being drawn, there is such a thing as diversity

 

[misha8904]

Ok then, what diversity factor do you use?
Can you just put in whatever demand you like, or does the RCD have to be equal and greater than the single larges load on the rcd side?
Skip

 

[misha8904]

Re: the total load of all the fuses was over 140 amps, ie: 32a fuses etc....

 

[fattony]

RCD's come in the following:

30A - 30mA
40A - 30mA
60A - 30mA
80A - 30mA
100A - 30mA

Diversty for final circuits i.e ring main is

100% of the current demand of the largest circuit + 50% of current demand of other circuits

From that you can work out what you will need

 

[davy_owen_88]

Remember though that those diversity figures are just guidelines, it is up to the designer/installer to assess the maximum demand - and IMO the diversity figures are pretty ridiculous for domestic premises. Assuming a standard house with 3 ring circuits, is it just me that thinks 58A after diversity is a bit over the top?