Rcd100ma or 80a

[Iona222]

Whats the maximum breakers current you should put on one. Would you go to 140amp on a 100amp during to diversity. Its there a rule of thumb.

Cheers gents.

 

[Rockingit]

Sorry - not sure I’m understanding the question. Are you asking if it’s OK to have a single RCD rated at 80A upstream of say 5 x 32A MCB’s?

 

[Iona222]

Sorry mate poor description. OK say your in front of a consumer unit and there isn't ant rcd protection. So being a quality sparky like myself you decide to fit one.

So you get say a 100amp rcd, how much amps should you put for it to cover. Like 32amp 32amp 32amp, 40amp, 40amp, 6 amp 6amp. Total 180 amp

What the total. Cheers.

 

[cliffed]

Sorry mate poor description. OK say your in front of a consumer unit and there isn't ant rcd protection. So being a quality sparky like myself you decide to fit one.

So you get say a 100amp rcd, how much amps should you put for it to cover. Like 32amp 32amp 32amp, 40amp, 40amp, 6 amp 6amp. Total 180 amp

What the total. Cheers.

It’s supposed to be no larger than the rated amperage on the main switch….seems impossible when you can have @ least 4-5 32amp mcbs before anything else.
Diversity may not be appropriate @ that point but on the final circuits it can be used.
Personally I wouldn’t worry about it,using an amp meter on the install would show low current use anyway on Flc.

 

[Lucien Nunes]

The RCD should be protected against overload either upstream or downstream. Examples:
100A RCD, 100A supply: total of MCB ratings not important because RCD protected upstream.
63A RCD, 100A supply: total of MCB ratings must not exceed 63A so that RCD is protected downstream.
63A RCD, 100A supply, total of MCB ratings with non fixed loads: No good, RCD is not protected.

You will often have a situation where due to diversity, the demand (and hence the main fuse rating) can be much lower than the total of the MCB ratings, but the RCD rating must be sufficient to handle the In, not the demand.

 

[Rockingit]

Have a re-read of chapter 13, may help clarify your thinking