Does this comply with 314?

Octopus · Aug 18, 2017

Been at a place today.......... brand new loft conversion.......... so an additional CU has been fitted for the lights and sockets ......................

Thinking specifically about 314.2 :

[ElectriciansForums.net] Does this comply with 314?

I would say that it doesn't............

Opinions please

and more to the point, this conversion probably cost about £45k so using RCBO's wouldn't have been noticed................

The last one I saw was where a new single RCD board had been used for the entire house and loft conversion.............. why do people do this?

Davisonp · Aug 18, 2017

Murdoch said:
What I was doing was in the main house - so not my "safe isolation".

FWIW the "other" CU was an older MK - with a 30Ma main switch!

If it was me I would have taken one of the other lighting circuits out of the old board and put it in the new board, then placed the new lighting circuit in the old board!

Is the “Other CU” with RCD as main switch supplying the new loft cu? No discrimination if that is the case?

diditrain · Aug 19, 2017

How much of the 45k, did the Electrician see though?

Midwest · Aug 19, 2017

If I was doing the installation for the loft conversion, I would of considered 314 and installed RCBO's.

In this install, if the RCD trips, and the occupier gets up in the middle of the night to investigate and trips over his bed pan, 'cos he's got no bed side light or room light, the installer has not done all he/she can to 'avoid danger & minimise inconvenience etc'.

So I agree with Murdoch IMO.

Octopus · Aug 19, 2017

Davisonp said:
Is the “Other CU” with RCD as main switch supplying the new loft cu? No discrimination if that is the case?

Split tails and Henley block

Deleted member 9648 · Aug 19, 2017

As already stated it's a non issue.
If the end user loses the loft conversion electrics he can run a lead from elsewhere until it's fixed. If it's just nuisance tripped then the rest of the house is still on so he can see to reset.

Octopus · Aug 19, 2017

wirepuller said:
As already stated it's a non issue.
If the end user loses the loft conversion electrics he can run a lead from elsewhere until it's fixed. If it's just nuisance tripped then the rest of the house is still on so he can see to reset.

I disagree .........IMHO the designer of the loft conversion circuits has failed to comply with the regs......

Octopus · Aug 19, 2017

diditrain said:
How much of the 45k, did the Electrician see though?

At a guess, maybe around £900

Midwest · Aug 19, 2017

wirepuller said:
As already stated it's a non issue.
If the end user loses the loft conversion electrics he can run a lead from elsewhere until it's fixed. If it's just nuisance tripped then the rest of the house is still on so he can see to reset.

Not easily done in the middle of the night, or if your elderly or infirmed or just a little bit squiffy. Not really a good design, if you have to faff around with extension leads (not everyone has one), when a couple of RCBO's is a simple but easy fix?

Deleted member 9648 · Aug 19, 2017

You are of course entitled to take that view.....but really your objection makes no sense. If it was installed on 2x RCBO's and the lighting one tripped during the night, and your elderly /infirm/squiffy type does not have a light plugged in or cant reach it then your RCBO has not improved their safety one bit.....Of course RCBO's are always preferable but to suggest this is non compliant with just two circuits on a separate RCD and the rest of the house unaffected is incorrect IMO.
A job I did last week involved 4 new circuits for kitchen equipment which I supplied from a 4 way DB with an RCD main switch, the rest of the existing installation is split over two RCD's on the existing DB. I have an NICEIC visit next month and he'll probably see this job. I'll let you know if he pulls it up as non compliant.

Midwest · Aug 19, 2017

wirepuller said:
You are of course entitled to take that view.....but really your objection makes no sense. If it was installed on 2x RCBO's and the lighting one tripped during the night, and your elderly /infirm/squiffy type does not have a light plugged in or cant reach it then your RCBO has not improved their safety one bit.....Of course RCBO's are always preferable but to suggest this is non compliant with just two circuits on a separate RCD and the rest of the house unaffected is incorrect IMO.
A job I did last week involved 4 new circuits for kitchen equipment which I supplied from a 4 way DB with an RCD main switch, the rest of the existing installation is split over two RCD's on the existing DB. I have an NICEIC visit next month and he'll probably see this job. I'll let you know if he pulls it up as non compliant.

Well, I seem to recall someone on this forum arguing that a dual RCD set up, was non compliance with 314. I think that's a bit extreme. What someone does with an installation after you've installed it, you have no control over. But in the example given here, at least having two separate RCBO's would give some scope.

In the example you've given, a loss of complete power to a kitchen, is unlikely to cause danger as suggested in 314, although it may well cause inconvenience. However, the control of both lighting & power for a bedroom at night by one RCD, could cause danger, dependant on the end user (when I designed this, did I do all that was reasonably practicable).

You may be aware that the draft for the 18th, will make more demand of the designer to consider unwanted tripping, (proposed) reg 531.3.2. Limiting down stream current to 30% of the RCD rating. So perhaps you kitchen design may not comply with the 18th?

Deleted member 26818 · Aug 19, 2017

Assuming it's a new build, it complies.
Could have been done better.

Octopus · Aug 19, 2017

spinlondon said:
Assuming it's a new build, it complies.
Could have been done better.

Not a new build. Loft conversion

Deleted member 26818 · Aug 19, 2017

New build as in new room in the loft.
Or are you saying the loft was already converted?

Deleted member 9648 · Aug 19, 2017

Midwest said:
Well, I seem to recall someone on this forum arguing that a dual RCD set up, was non compliance with 314. I think that's a bit extreme. What someone does with an installation after you've installed it, you have no control over. But in the example given here, at least having two separate RCBO's would give some scope.

In the example you've given, a loss of complete power to a kitchen, is unlikely to cause danger as suggested in 314, although it may well cause inconvenience. However, the control of both lighting & power for a bedroom at night by one RCD, could cause danger, dependant on the end user (when I designed this, did I do all that was reasonably practicable).

You may be aware that the draft for the 18th, will make more demand of the designer to consider unwanted tripping, (proposed) reg 531.3.2. Limiting down stream current to 30% of the RCD rating. So perhaps you kitchen design may not comply with the 18th?

I am not aware of those proposals, are you saying it is proposed that a 63a RCD would be restricted to a load of 21a?.....then presumably a 32a RCBO would be restricted to under 11a?
So a 10kw shower would need a minimum 135a RCBO ?....Sorry if I'm having a blonde moment but that just doesn't make any sense.