RCD protections with a FCU, what will paperwork tell me. Ask questions and find answers to many subjects relating to electrics and electrical work

[ericmark]

I think the electricians have made an error, I have had an UPS supply for central heating and three freezers, the latter has RCD type A sockets, but the boiler seems to still have the original switched FCU.

So is seems likely the boiler, pumps, motorised valves, and thermostats will have no RCD protection.

The earth rod was a very low reading of 0.37 ohms, I thought he was testing with the DNO earth connected, but no just the rod, so no problem that way.

However my worry is some plumber doing a service on the boiler switching off wrong FCU and getting a belt on a non RCD protected circuit, all the original were on RCBO's.

My RCD tester my son has, so the question is will paperwork show all the RCD's when SWA and RCD sockets are used? Will the paperwork make it obvious there is an error if there is one? Will it show two or three disconnection times on the paperwork, as all the paperwork I have used only has one slot for disconnection time per circuit.

It is enough to make some one travel 100 miles to fix? A RCD FCU is cheap enough, so swapping it not a problem, but should I touch their work.

It is notifiable work as all work done was either outside or in a kitchen, and I live in Wales.

[ericmark]

It has been pointed out that for a 13 amp fuse the PSCC needs to be 95 amp and an inverter will not provide this, a three amp fuse needs 14 amp so it may be OK with 3 amp fuse, but two pumps, two motorised valves and central heating really needs 5 amp fuse, and my copy of BS 7671 does not give the ELI for 5 amp fuse.

[ericmark]

The saga continues, seems the iboost+ fitted uses DC not AC, loads of warnings in the installation instructions about turning the volt meters to DC to measure.

But the CU is full of type AC RCBO's, even a type A is only good for 6 mA so would need a RDC to trip should DC be found or the RCD will not work.

However the inverter states one can use type AC RCD's, so once I was indecisive, now I'm not so sure! Am I worrying about nothing? Does anything really need doing? After all when I moved in only a very small amount of the property was RCD protected, I had fitted 14 x type B RCBO's only latter did I realised it was curve B type AC. It said in large writing type B on the boxes.

I can't see it is worth changing them all, if it was two or three RCD's then may be, but 6 mA is not much, so even if changed can't see much of a gain, so inclined to ignore it.

Thoughts please.