K
kai
Why are Type B RCBO's so hard to get nowadays?
using type Cs is fine provided you keep an eye on the earth fault loop impedence.
the reason we don't tend to reccomend larger type C breakers to diyers is because they have no way to determine the earth fault loop impedance at the origin of the supply so we have to assume the worst allowed case.
the reason we don't tend to reccomend larger type C breakers to diyers is because they have no way to determine the earth fault loop impedance at the origin of the supply so we have to assume the worst allowed case.
K
kai
I'll never use a type C in a house, unless I spend time bonding everything in the home back to the main earthing terminals with 16.0. sq.mm. earth cable!!! 
Just thinking where I have seen references on this point. On site guide has the following to say regarding choice of circuit breaker: (Table 7.2B)
Type 1 or B: domestic and commercial installations having little or no surge.
Types 2,3 or C: general use in commercial/industrial installations where the use of fluorescent lighting, small motors etc can produce switching surges that would operate a type 1 or B circuit breaker.
Type 4,D: Ruitable for transformers, x-ray machines, industrial welding etc where high inrush currents may occur.
So standing advise is type B, and as I said before the only general case where type Bs cause problems seems to be endless nuisance tripping for lights. But then, I don't think you would be wanting to use a RCBO for lights anyway. Otherwise it does say only use a C if a B will trip.
Oh and Kai, I think what you need to do is worry how good the earth to the main terminal is, not the bonding around the house.
Type 1 or B: domestic and commercial installations having little or no surge.
Types 2,3 or C: general use in commercial/industrial installations where the use of fluorescent lighting, small motors etc can produce switching surges that would operate a type 1 or B circuit breaker.
Type 4,D: Ruitable for transformers, x-ray machines, industrial welding etc where high inrush currents may occur.
So standing advise is type B, and as I said before the only general case where type Bs cause problems seems to be endless nuisance tripping for lights. But then, I don't think you would be wanting to use a RCBO for lights anyway. Otherwise it does say only use a C if a B will trip.
Oh and Kai, I think what you need to do is worry how good the earth to the main terminal is, not the bonding around the house.
Don't forget kai has a fetish for festooning yellow & green cable everywhere...
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Most appliances in todays homes warrant type Cs; ie Fluoros, electronic equipment, multispeed washing machines, S&M equipment, etc...
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