30mA RCD as main switch

[leep82]

Done a little bit of searching and found that a situation such as the title of this thread would be against current regs, heres my situation. Been to look at a few jobs on a bungalow. The customer wants lights on there garage, ( which already has a supply present), an outside socket, and an extra lighting point in there living room. Currently the installation has no RCD protection whatsoever. Supply is TNCS and feeds a DB with only 5 circuits ( sockets, cooker, lighting, garage and burglar alarm ). Could it be argued that i have improved the state of the installation and note it as a deviation if i fitted a 30mA RCD as the main switch. Its just that cost is a big issue for the customer and i already have in my possesion the RCD so this would be much cheaper than going down the 3 separate RCBO's route for the individual circuits i would be working on.

 

[Octopus]

How to you plan to comply with minimising inconvienience?

 

[trev]

So you know it's against the regs but you're asking if it'll be ok to do anyway as you've got a bit spare off another job?
Think about this a bit more mate, the solution is not that difficult.

 

[Plonker 3]

Cost over convenience. Just think about what you have just said.

 

[Simonslimline]

Edit..... RCBO already mentioned

 

[Plonker 3]

Why don't you want to fit a RCBO?

Corrected that for you.

 

[Darkwood]

Split board fully loaded cheaper than 3 rcb's... if money is such an issue then tell them to first upgrade the DB with the money and save for the additional ... no room for breaking the regs here to try save money it is what it is...

A good explanation and options should have the customer understanding, I would still be putting the Intruder alarm on its own RCBO in the new board anyway as this could be classed as a potential nuisance if sharing an RCD and the SAB takes over at battery drain.

 

[HappyHippyDad]

I suppose you're right in that it 'could be argued', but you'd probably lose the argument Leep :smiley2:

3 RCBO's maybe £45 in total with a bit of looking around.

I would definitely not fit an RCD as a main switch!

I'm not entirely sure without checking but I think the only one of the jobs that definitely needs an RCD adding is the outside socket, thats if theres no channeling in less than 50mm with the other 2 jobs. Not sure though, Murdoch will know.

 

[Badged01]

Done a little bit of searching and found that a situation such as the title of this thread would be against current regs,

Not saying I'd do it but enlighten me as to why its against regs? As I see it, and happy to be corrected .....

1 - RCD's are rated for use as isolators in BS7671.

2 - BS7671 requirement to avoid danger/minimise inconvenience. Im guessing this is a residence where you could expect people to know their house in the event of a failure and avoid falling down the stairs. Unless there are say standard lamp lights on the sockets circuits on when the light circuit goes down, its dark anyway!!. To avoid danger/minimise inconvenience I could interpret BS7671 meaning no single lighting circuit, no single ring/radial socket circuit, no single cooker circuit, no single immersion circuit etc ..... and no single supply to the CCU!!.

Where do you balance risk v practicality v cost?!?!

 

[leep82]

Done a little bit of searching and found that a situation such as the title of this thread would be against current regs,

Not saying I'd do it but enlighten me as to why its against regs ? As I see it, and happy to be corrected .....

1 - RCD's are rated for use as isolators in BS7671.

2 - BS7671 requirement to avoid danger/minimise inconvenience. Im guessing this is a residence where you could expect people to know their house in the event of a failure and avoid falling down the stairs. Unless there are say standard lamp lights on the sockets circuits on when the light circuit goes down, its dark anyway!!. To avoid danger/minimise inconvenience I could interpret BS7671 meaning no single lighting circuit, no single ring/radial socket circuit, no single cooker circuit, no single immersion circuit etc ..... and no single supply to the CCU!!.

Where do you balance risk v practicality v cost?!?!

i dont have my regs at the minute so cant check, lent them to a lad at work doing his 17th edition, so i did a quick search on here to see if had been asked before and found varying answers. And even now you are saying RCD are acceptable as isolators. If its just about inconvenience what would i be achieving by splitting the circuits, bearing in mind there is only 5 for the whole property, and being a bungalow there is certainly no danger of anybody falling down the stairs should the RCD trip. Is it just about inconvenience?

 

[Darkwood]

Not saying I'd do it but enlighten me as to why its against regs? As I see it, and happy to be corrected .....

1 - RCD's are rated for use as isolators in BS7671.

2 - BS7671 requirement to avoid danger/minimise inconvenience. Im guessing this is a residence where you could expect people to know their house in the event of a failure and avoid falling down the stairs. Unless there are say standard lamp lights on the sockets circuits on when the light circuit goes down, its dark anyway!!. To avoid danger/minimise inconvenience I could interpret BS7671 meaning no single lighting circuit, no single ring/radial socket circuit, no single cooker circuit, no single immersion circuit etc ..... and no single supply to the CCU!!.

Where do you balance risk v practicality v cost?!?!

No one is trying to get silly or wrap it in red tape... my one point which I would be to consider subject to nuisance issues is a security alarm if its a SAB set up on a shared RCD, the new amendments are also due out soon and increasing the requirements for RCD protection and reducing the cases where it can be omitted.

A sit down and a chat with the customer to explain what RCD protection is about, noting at present the existing electrics do not need to be upgraded but your own work has to comply with new standards so at the expense of a little extra cost a board change is recommended and has the addition of affording extra protecting if a fault occured.

Ignore the cash strap talk if they were they would not be adding garage lighting + socket and indoor light, its not the most essential of needs when your cash strapped.

 

[Darkwood]

Not saying I'd do it but enlighten me as to why its against regs? As I see it, and happy to be corrected .....

1 - RCD's are rated for use as isolators in BS7671.

2 - BS7671 requirement to avoid danger/minimise inconvenience. Im guessing this is a residence where you could expect people to know their house in the event of a failure and avoid falling down the stairs. Unless there are say standard lamp lights on the sockets circuits on when the light circuit goes down, its dark anyway!!. To avoid danger/minimise inconvenience I could interpret BS7671 meaning no single lighting circuit, no single ring/radial socket circuit, no single cooker circuit, no single immersion circuit etc ..... and no single supply to the CCU!!.

Where do you balance risk v practicality v cost?!?!

Domestic wise nuisance tripping is classed as not a big issue when you move to elderly residence then things like rcbo for boiler become a forethought so a vulnerable person doesn't lose heating if a fault occurs on a non related circuit they can't reset, essential luxury in winter for a frail old dear! ..other than that not a high priority it comes more into play in commercial and industrial where lost power can be costly effecting everything from production to telephone systems.

 

[leep82]

As another example what if you were asked to do some work on an install that already had 30mA RCD as a main switch. A new circuit for example that required RCD protection. As far as your concerned your circuit is in line with current regs although the install on a whole is not. Is this ok ?

 

[Badged01]

..... you are saying RCD are acceptable as isolators.

Trust me Im a plumbers mate, I know they are acceptable and modern ones can even isolate whilst carrying load!

.....what would i be achieving by splitting the circuits, bearing in mind there is only 5 for the whole property ....

Exactly, you could argue you don't have to ......... if the lighting circuit goes down your doomed to darkness however you split it. And with only one cooker circuit you will be very inconvenienced if your cooking your sunday roast and that circuit pops!!

 

[Badged01]

As another example what if you were asked to do some work on an install that already had 30mA RCD as a main switch. A new circuit for example that required RCD protection. As far as your concerned your circuit is in line with current regs although the install on a whole is not. Is this ok ?

Depends if the current RCD protection is being used to meet disconnection times and the new circuit requires an RCD for additional protection? The mind can boggle at the implications of having two RCD's!!