I was called out to a static holiday/residential caravan today. Nuisance tripping was reported. Apparently the electrics were reliable before the van was moved to a new pitch on the same sandy site. The van's consumer unit comprises 1 30mA R.C.D., a 32 Amp socket M.C.B. and a 6A lighting M.C.B.
The pitch permanent "hook up" point comprises a 30 mA R.C.D. and a 16 Amp M.C.B.
The lady has many high powered appliances, 2kW kettle, three 2kW+ room heaters, a 2.2kW coffee machine etc. The heating is normally by bottled gas.
The two R.C.D.s tested out fine, not over sensitive. But the van owner can not remember which devices tripped off over a period of time. Once the nearby brick supply building had to be accessed to reset something, but we were not allowed even just to look inside it today by the site owners. Very unhelpful.
Anyway, all appliances tested good, no faults. I presumed that the lady had plugged too many items in at once. Guidance note 7, page 58 Fig. 7.1 it shows 4 possible separate vans being supplied via a single 100 mA R.C.D.
So, looking at the possibility of nuisance tripping if 4 vans each leak say 20 to 30 mA, the 100 mA R.C.D. could trip off blacking them all out. Should a time delayed 100mA type be used? The Guidance note says that the 100 mA R.C.D. is chosen to discriminate with the pitch socket outlets R.C.D.s. But, if say 100mA was to flow from a van fault, both the 30mA pitch socket R.C.D. AND the 100mA brick supply building could trip off together. This would then deprive a total of 4 vans of a supply.
Comments please.
Thanks,
Z.
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