Dual RCD

[SPECIAL LOCATION]

The question was about regs not if they are any good
Yes we have all come across RCDs tripping and people losing half there house a pain but not rocket science to repair.
If the customer doesn’t want to pay the extra £200 for RCBOs it’s on them
I don’t use them as a rule but preference is not a regulation
Regulation 531.3.2

Repairs may not be rocket science....
But if you've been doing this job for more than a couple of years, will be aware they can be long, drawn out and expensive on labour / call-out charges... Whilst trying to establish exactly which circuit(s) is/are causing the tripping... especially if its an intermittent fault.
and can easily mount up to multiple days labour costs....

Customer soon get very irritated if they a loosing power frequently at a critical time..
And get very concerned that the power may trip off while they are away from home / on holiday..
so they come back to a freezer that has thawed out..
typically considering this a bit more than just 'a pain'.

And when you have got the power back on... and the customer asks "how can we stop this happening again?"
the answer is.... take out the cheap tat of a dual RCD CU that captain cowboy fitted..
and install a more professional solution.

The costs of fixing these problems is generally a lot more expensive when offset against a full RCBO board..

But if the customer is not being given the realistic remedial costs to compare with a dual RCD option..
then they don't stand much chance of making a sensible decision do they?

Reg's are guidance
and when there is a cost effective easy way to...
"minimise inconvenience in the event of a fault" 314.1 (i)
and
"reduce the possibility of unwanted tripping of RCDs due to excessive protective conductor currents, not due to a fault" (AKA cumulative leakage)..
314.1 (iv)

Why would any competent, experienced electrician choose to ignore guidance that provides a better design and functional solution to a prospective customer who is going to be paying their wage...?

 

[NozSpark]

I had a customer who used to phone home twice a day whenever he was on holiday to check if the RCD had tripped due to an intermittent fault (and then phone the neighbour to reset it if it had).... I couldn't find much of a fault but he agreed to replace the single RCD protected board for a RCBO board.... he never had another trip

 

[kerching]

Double Pole RCBOs are the way forwards and should have been mandated in AM2, but what do I know?
Not a Lot is the answer, other than I fitted them at home about 5 yeas ago

 

[peterspurs]

again, which reg? so far the only one youve provided suggests otherwise...

Basically means split up circuits on dual boards
25 year old 3 bed house may only have 6 circuits up and down lights different RCD
Up and down sockets different RCD
Kitchen and Oven different RCD

It’s the people who pay for the work who need convincing

 

[mort2376]

Basically means split up circuits on dual boards
25 year old 3 bed house may only have 6 circuits up and down lights different RCD
Up and down sockets different RCD
Kitchen and Oven different RCD

It’s the people who pay for the work who need convincing

And 9 times out of 10 you can't split the lighting circuits due to a shared neutral on the landing light.

The dual rcd boards only comply on a new install where they are loaded correctly.

I totally agree that they should have been phased out by Amd2. Maybe we should all wait for the consultation on Amd3 and push for it ??

 

[Sidewinder]

There has NEVER been a prohibition on using individual RCBOs on circuits.
Clause 531.3.2 requires that individual RCBOs are considered for residential premises.
It also requires that in-service leakage is < 30% of the RCD nominal earth leakage rating per device.
Good luck in keeping the leakage on a dual RCD board at 10 mA when you have multiple final circuits on an RCD.
The intent of 531.3.2 is that domestic premises are all RCBO.
It also refers you back to 314.
If you have multiple final circuits on a single RCD, then how do you meet 314.1(i) & (iv)?
Forget split boards, they are not compliant, there are too many clauses pointing you toward RCBOs.
The previous posts have covered this.
Forget how much the customer can afford, this argument is pretty poor now because of the level at which standard RCBOs are priced at.

 

[Sidewinder]

And 9 times out of 10 you can't split the lighting circuits due to a shared neutral on the landing light.

The dual rcd boards only comply on a new install where they are loaded correctly.

I totally agree that they should have been phased out by Amd2. Maybe we should all wait for the consultation on Amd3 and push for it ??

Well clause 531.3.2 already suggests they are not compliant.
Not sure how anyone could justify the use of a split board and prove they meet all the requirements.

 

[Sidewinder]

Basically means split up circuits on dual boards
25 year old 3 bed house may only have 6 circuits up and down lights different RCD
Up and down sockets different RCD
Kitchen and Oven different RCD

It’s the people who pay for the work who need convincing

No it doesn't.
It means what it says.
Also limiting in-service leakage to be less than 9 to 10 mA per device is impossible if you have multiple final circuits on one RCD.

Remember a 30 mA device can legitimately trip at 16 mA by design and not be deemed faulty by the manufacturer, product standard or 7671.

 

[binky]

Your cheap if you charge £10 extra per circuit
Not seen RCBOs under £10

But it does comply

MCB + £10, you can get RCBOs for under £10, but I don't like those.

 

[Badger]

I use rcbos from fusebox ams havent had any problems I generally wont install dual rcd now at all

 

[Murdoch]

Looking at @Sidewinder 's post above I think that 531.3.2 (iii) is the clincher here - and the reg that few people seem to acknowledge or understand.

Especially when so many homes are stuffed full of electronic stuff and many old homes only have 1 socket circuit

 

[sirsparkabit]

Putting all things in perspective ,I just find it easier to tell clients I will give them the latest best equipment available for my price , why you would want to split it all down before you even get the job amazes me total parts plus labour = complete price you are charging . Should you choose to alter the balance of the 2 later on you will still be charging the same price .
Customer gets rcbo populated board you get paid everyone's happy .

We all know whilst these are on the market some customers will try and choose the cheap route so I don't give them the option.
They choose who they want to do the install so I just don't complicate matters KISS is what I tell myself.
Fault finding on plastic duel rcd boards is part of your bread and butter and will be for years to come.
Long live Business Sense.

 

[Murdoch]

It’s the people who pay for the work who need convincing

I never quote for dual RCD boards - so its my quote or not and on the rare occasion I'm asked about the benefits of RCBO boards over dual RCD, I simply say do you want to lose 1/2 your circuits on Christmas day?

 

[Badger]

Looking at @Sidewinder 's post above I think that 531.3.2 (iii) is the clincher here - and the reg that few people seem to acknowledge or understand.

Especially when so many homes are stuffed full of electronic stuff and many old homes only have 1 socket circuit

Makes our home look modern then with 9 socket circuits including shed sockets, network security sockets, computer sockets, kitchen skts, down skts, up skts, outside skts and workshop skts and pond skts

 

[Badger]

Makes our home look modern then with 9 socket circuits including shed sockets, network security sockets, computer sockets, kitchen skts, down skts, up skts, outside skts and workshop skts and pond skts

Oh forgot there's also q circuit for the Christmas lights aswell

 

[Murdoch]

sockets

up, down left, down right, extension, fridge, os sockets, loft/ boiler = 7

 

[sirsparkabit]

Did anyone mention understairs cupboard skt

 

[Andy™]

It’s the people who pay for the work who need convincing

simple... dont give them the option that doesnt comply

do you also give a cheaper price for skipping the bonding?

 

[peterspurs]

simple... dont give them the option that doesnt comply

do you also give a cheaper price for skipping the bonding?

No but is that something you do ?
Do share anymore tips you have

 

[King Arthur]

Makes our home look modern then with 9 socket circuits including shed sockets, network security sockets, computer sockets, kitchen skts, down skts, up skts, outside skts and workshop skts and pond skts

I forget how many circuits we have but I know we have 7 CUs