Rcd size

[midgetman]

Hey can you please explain rcd size. Garage cu it comes with 6amp mcb plus 16 amp mcb with 63amp rcd. While same cu bought else where maybe have 40 amp rcd and another 25 amp rcd.

 

[Deleted member 26818]

The amperage shown on an RCD, is the maximum current the device is capable of switching underload without suffering damage.

 

[telectrix]

as spin says, the rating (A) is the max. A the |RCD will cope with. no matter if it's 63A and you're only pulling 20A. it's like having a car that will do 140mph, and driving it at 70 mph.

 

[midgetman]

Tidy. Why thru not all fitted with same size rcd then? Or is it no big deal

Cornish small man.

 

[trev]

They're not a standard rating because there's no standard installation for them to be fitted to for example you'd maybe need a 100 amp on one type of consumer unit but a 40 amp on another

 

[midgetman]

Yes cheers these are advertised as garage cu. Just interested why one manufacture would give you 63amp rcd yet another 40amp and another 25amp. They all come with 16amp mcb , 6amp mcb.

Cornish small man.

 

[Richard Burns]

25 Amp sounds low for a garage CU with those breakers, but would be unlikely to be overloaded.
I think the likely reason is that it depends on what is in overstock at the time!
80 and 100 A RCDs are used a lot in main CUs and can occasionally be cheaper than the smaller rated ones, however if manufacturers make too many of the lower rated ones then CU assembly will use those as they will be cheap; it is all business driven once the regulations are out of the way.:greedy: