Use of RCD FCU when not marked as type A.

[ericmark]

@ebee said the following in another thread.

I would caution against adding an RCD FCU just for the bathroom part of a larger circuit (i used to do it) .
Someone pointed out that lets say an existing bedroom circuit could have a disconnection time of 5.0 seconds under previous versions.a fault on say a bedroom portion of that circuit would leave a potentially dangerous voltage on that c.p.c entering the bathroom and the FCU RCD would not detect it.

Not to mention that the old BS for RCD protection has been disallowed for a while now anyway.

I don't have the supply to my freezers and boilers coming from the consumer unit, so the sockets are type A RCD sockets, but the FCU has at the moment no RCD protection, I got a RCD FCU with the intention of fitting it, but CEF did not have any claiming to be type A, so I have a standard one off their shelf, I have not yet fitted it, one as I have had a fall and not in fit state yet, and two not worked out how to isolate the circuit. I have six isolators, two DC from solar panels, two built into the consumer units, and two feeding the consumer units, non seem to switch off the UPS supply, but I know it's correct as have a compliance certificate, but seems only way is to unplug some thing from the inverter. But I am sure I have missed something and once well enough I will find the isolator.

But it is the use of RCD FCU why I am posting, I only have the 17th edition, I know things have changed, but one should the boiler supply have been RCD protected to be compliant? and two can I use a RCD FCU on this circuit. I know technically maybe I should not DIY the change to a RCD FCU as it is work in a kitchen so special location, but I am not really worried about that, I will say I thought I was in England and forgot I was in Wales, and had a senior moment.

But @ebee comments started me to wonder if I should insist the installer does the 150 mile round trip to correct it.

 

[ericmark]

I have fitted the RCD FCU and it seems two stage isolation required, both the large red turn switch, which seems to be what is expected and also press this button

nothing written on it to show what it is for, it looks more like a turn buckle to hold casing on than an isolator. Not impressed.

 

[JohnW2]

I don't have the supply to my freezers and boilers coming from the consumer unit, so the sockets are type A RCD sockets, but the FCU has at the moment no RCD protection,

Can you perhaps clarify what that means? If the supply to your freezer/boiler is not 'coming from the CU', where is it coming from, and what has the RCD protection of sockets got to do with it?

Are you perhaps trying to say that the supply to the freezer/boiler, wherever it comes from, is not RCD/RCBO-protected - and, if so, why is that?

Kind Regards, John

 

[ericmark]

Sorry my freezers and boiler are on an UPS which is part of the solar system so even with no grid power, my freezers and heating will continue to work. So the supply is from the inverter, there are three new isolators two for DC and one for AC and I thought turning off the AC isolator would allow me to work on the UPS supply, but no, using my non contact volts detector at least I could see still live.

It seems to make dead both the button needs pressing and the isolator turned, if either not done it stay live, I know whole idea is for it to be uninterruptible, but I would have expected to see detailed instructions on the unit, not having to phone the electrician who installed it to find out how to isolate it.

The wiring to the sockets and FCU is either SWA or surface so the RCD type A sockets are clearly no problem, but the FCU had no RCD so any items associated with the boiler were not RCD protected, they are now, fitted the RCD FCU about an hour ago. But the FCU does not say type A, it says conforms to BS 7288 : 2016 & BS 1363 30 mA at 40 mS but CEF did not have any which state type A, neither did Screwfix.

The risk is low, we don't play with the boiler, but one would have thought any TT supply and once the grid goes down it is TT, should be RCD protected. But is a RCD FCU good enough if not giving the type?

 

[JohnW2]

Sorry my freezers and boiler are on an UPS which is part of the solar system so even with no grid power, my freezers and heating will continue to work. So the supply is from the inverter,

Fair enough. Thanks for clarifying.

there are three new isolators two for DC and one for AC and I thought turning off the AC isolator would allow me to work on the UPS supply, but no, using my non contact volts detector at least I could see still live. ... It seems to make dead both the button needs pressing and the isolator turned, if either not done it stay live, I

That sounds positively dangerous, don't you agree?

The wiring to the sockets and FCU is either SWA or surface so the RCD type A sockets are clearly no problem, ...

I don't really understand that comment, but I don't think it is relevant.

but the FCU had no RCD so any items associated with the boiler were not RCD protected, they are now, fitted the RCD FCU about an hour ago. But the FCU does not say type A, it says conforms to BS 7288 : 2016 & BS 1363 30 mA at 40 mS but CEF did not have any which state type A, neither did Screwfix.

Rather odd, so I suppose you'll have to ask the manufacturer - I presume you know the make and part number? Mind you, speaking personally, I don't think I would lose any sleep about a freezer and boiler being protected by a Type AC RCD (if that's what it is).

... but one would have thought any TT supply and once the grid goes down it is TT, should be RCD protected.

Yes, assuming that the output of your UPS is earth-referenced.

Kind Regards, John

 

[ericmark]

That sounds positively dangerous, don't you agree?

Yes I do, in fact if I was doing an EICR think I would give it a code C2. One should be able to lock off an isolator, and clearly no way to lock off a push button, I worked as if it was live to be on the safe side.

514.11.1 A notice of durable material in accordance with Regulation 537.2.1.3, shall be fixed in each position where there are live parts which are not capable of being isolated by a single device. The location of each disconnector (isolator) shall be indicated unless there is no possibility of confusion.

Can't see how that is satisfied. There are a whole load of British standards for isolation can't see how it can apply to a push button. I would have expected at least a notice and looking at the manual for the inverter it shows

which shows an "AC Breaker" on the UPS supply. And a DC Switch on the battery supply neither seem to have been fitted, however I am guessing I have the right inverter as to date all I have is a compliance certificate which was issued before the work was completed.