Could an unfused R.C.D. protected spur, from a complient ring final circuit, supplying a single outdoor socket via 1.5mm2 6242Y cable of max. length 300mm through a brick wall from an indoor socket outlet be considered compliant?
OK, you've just about convinced me that Z's MCB will open quickly enough at a few hundred amps to save the 1.0mm².
I think we still have a difficulty in deciding how far this protection goes as the fault current increases though.
Hopefully we're all agreeing with k=115 and to we need to keep the energy let-though below 13,225 A²s to meet BS 7671's requirement to protect the 1.0mm² and the associated insulation.
If the fault current was as high as 3,000A then the data from BS EN 60898 seems to say we do have a problem as it says the energy let-through is 18,000 A²s.
Could I just take 13,225A²s and work backwards from I²t using 0.01s and come up with 1150A - or is that an over-simplification?
OK, you've just about convinced me that Z's MCB will open quickly enough at a few hundred amps to save the 1.0mm².
I think we still have a difficulty in deciding how far this protection goes as the fault current increases though.
Hopefully we're all agreeing with k=115 and to we need to keep the energy let-though below 13,225 A²s to meet BS 7671's requirement to protect the 1.0mm² and the associated insulation.
If the fault current was as high as 3,000A then the data from BS EN 60898 seems to say we do have a problem as it says the energy let-through is 18,000 A²s.
Could I just take 13,225A²s and work backwards from I²t using 0.01s and come up with 1150A - or is that an over-simplification?
