80A 100mA RCD in Domestic TT installation?

[leascliffe]

Hi,

I am starting out as a domestic installer and would really like some of your advice please??

I went to preview a job today to replace some pendant light fittings. The customer said the CU was replaced in 2010 together with a new earth rod being a TT supply. The overhead lines come into the distributor's fuse, tails out to the meter and just one pair of tails from the meter into an MK insulated C/U. The C/U consists of a 80A 100mA Time delayed RCD as main switch and 10 MCB's. There does not appear to be any other C/U at the property so I was wondering why the original installer went for a time delayed 100mA RCD?

I'm concerned there is no 30mA protection and believe the 100mA time delayed RCD should be swapped for a standard 30mA. Wondered if any of you have experienced the same and agree or disagree? Thanks!

 

[jamesBoater]

30ma rcd,s covering the final circuits, ideally the time delayed rcd covering the whole installation upfront.

 

[trev]

It should have both.

 

[GLENNSPARK]

get the 100mA s type upfront....30mA RCDS for your finals....
is there a garage here by any chance?

 

[leascliffe]

get the 100mA s type upfront....30mA RCDS for your finals....
is there a garage here by any chance?

Thank you all for your replies so far, much appreciated! Glennspark, yes there is a garage but the customer said there's nothing in there, but definitely worth a look me thinks!

My house is a TT supply and I replaced the C/U here for my first Elecsa Assessment, the board is an insulated dual rcd board, just a 100A main switch upfront (no time delayed RCD) and the assessor did not pick up about any missing 100mA time delayed RCD, do the regs say we have to put the 100mA upfront as well as the 30mA to the finals? Will have a read this evening....

 

[MDJ]

individual rcbos IMO is the way to do it with a 100 MA s type as the incommer, but it isn't the only way, Glenn and Trev are right though and the dual rcd boards with 30 ma rcds is a cheap way but still acceptable, you don't need the 100ma s type, but do need 30 ma

 

[trev]

The regs don't make this mandatory but it is the way forward.

 

[Octopus]

Plastic CU, dual 30mA RCD's OK. Metal CU you also need the upfront RCD.

 

[trev]

Would you not have an S type Murdoch?

 

[Deleted member 72666]

Would you not have an S type Murdoch?

I'd prefer a DB4!

 

[Octopus]

Would you not have an S type Murdoch?

Not essential on a plastic CU.

 

[GLENNSPARK]

Thank you all for your replies so far, much appreciated! Glennspark, yes there is a garage but the customer said there's nothing in there, but definitely worth a look me thinks!

My house is a TT supply and I replaced the C/U here for my first Elecsa Assessment, the board is an insulated dual rcd board, just a 100A main switch upfront (no time delayed RCD) and the assessor did not pick up about any missing 100mA time delayed RCD, do the regs say we have to put the 100mA upfront as well as the 30mA to the finals? Will have a read this evening....

if its a plastic C/U then keep the 100mA s type ....they may need this in future for the garage feed should they wish to go down the route of a supply in there....
this is what i was thinking ahead about at #4

 

[Deleted member 9648]

Hi,

I am starting out as a domestic installer and would really like some of your advice please??

I went to preview a job today to replace some pendant light fittings. The customer said the CU was replaced in 2010 together with a new earth rod being a TT supply. The overhead lines come into the distributor's fuse, tails out to the meter and just one pair of tails from the meter into an MK insulated C/U. The C/U consists of a 80A 100mA Time delayed RCD as main switch and 10 MCB's. There does not appear to be any other C/U at the property so I was wondering why the original installer went for a time delayed 100mA RCD?

I'm concerned there is no 30mA protection and believe the 100mA time delayed RCD should be swapped for a standard 30mA. Wondered if any of you have experienced the same and agree or disagree? Thanks!

Are you sure they are simply MCB's and not RCBO's.?....(apologies if this is insulting your intelligence but you have stated you are just starting out)

 

[Redvanman]

Got to be PVC board, you don't need 100mA rcd upfront but as you've got it might as well change mcb to rcbo otherwise you've got to have two rcd

 

[leascliffe]

Are you sure they are simply MCB's and not RCBO's.?....(apologies if this is insulting your intelligence but you have stated you are just starting out)

Don't worry, I'm used to being insulted :wink_smile: Sure, they are all MCB's. I think the customer will only be prepared to swap the 100mA for a 30mA at the moment, there's no room to have the 100mA upfront in another small enclosure. I like the idea of keeping the 100mA as it is but replacing the MCB's for RCBO's, just not sure the customer will like the price tag...assuming the MK Sentry boards are big enough to take RCBO's (all 12 of them)

Thanks for all your advice, I'll let you know the outcome

 

[Engineer54]

Not essential on a plastic CU.

I'm not quite following your logic here. Why do you think a metal CU requires an ''essential'' up front S type RCD, but a plastic CU doesn't??
The S type RCD is as far as i'm concerned, there to provide the much needed extra protection on a TT installation, rather than relying on a single RCD devices that are frankly not known for their operational reliability!!

As far as the OP situation is concerned, he should have both, either in the form of a dual 30mA RCD, or via RCBO's!! As it stands at the moment, the single S type 100mA RCD CU, doesn't comply with either the present regulations, or the regulations in force at the time of installation (2010)!!

 

[leascliffe]

I'm not quite following your logic here. Why do you think a metal CU requires an ''essential'' up front S type RCD, but a plastic CU doesn't??
The S type RCD is as far as i'm concerned, there to provide the much needed extra protection on a TT installation, rather than relying on a single RCD devices that are frankly not known for their operational reliability!!

As far as the OP situation is concerned, he should have both, either in the form of a dual 30mA RCD, or via RCBO's!! As it stands at the moment, the single S type 100mA RCD CU, doesn't comply with either the present regulations, or the regulations in force at the time of installation (2010)!!

Thanks Engineer54, my thoughts about the original installation are the same as yours, their company name is on a BIG sticker on the front of the C/U, the customer is trying to let the house and has been chasing the company for a copy of the original EIC, but the bloke hasn't replied...

 

[Engineer54]

If a cert was ever officially issued, the LABC should have a copy!!

 

[leascliffe]

If a cert was ever officially issued, the LABC should have a copy!!

The customer has a Building Regs Compliance Cert but not an EIC and has been chasing one ever since. NAPIT told her they don't keep a copy of it, so will try the LABC, cheers

 

[Jay Sparks]

..........

 

[Octopus]

The customer has a Building Regs Compliance Cert but not an EIC and has been chasing one ever since. NAPIT told her they don't keep a copy of it, so will try the LABC, cheers

More fool the client for paying the bill and not getting the certificate.

 

[Jay Sparks]

The customer has a Building Regs Compliance Cert but not an EIC and has been chasing one ever since. NAPIT told her they don't keep a copy of it, so will try the LABC, cheers

The LABC wont have a copy of the EIC either.....when you notify a job, you dont send them a copy of the EIC, you just give them the Number you assign to the EIC. Well at least thats what you do with Elecsa.

 

[Engineer54]

The LABC wont have a copy of the EIC either.....when you notify a job, you dont send them a copy of the EIC, you just give them the Number you assign to the EIC. Well at least thats what you do with Elecsa.

So the only complete official copy of the certificate, is the one issued to the customer?? That sounds totally crazy to me!!

So what happens when and if say an electrician emigrated, as it sounds to me the only actual copy of any cert, is held by the electrician/company that conducted the work and completed a certificate. So where's the checks and balances?? How does anyone check anything, when something goes belly up, as far as i can see it would be an easy task to falsify a copy of any cert issued....

 

[Jay Sparks]

So the only complete official copy of the certificate, is the one issued to the customer?? That sounds totally crazy to me!!

So what happens when and if say an electrician emigrated, as it sounds to me the only actual copy of any cert, is held by the electrician/company that conducted the work and completed a certificate. So where's the checks and balances?? How does anyone check anything, when something goes belly up, as far as i can see it would be an easy task to falsify a copy of any cert issued....

I Completely agree!!! When I enter the details of the install on the Elecsa website, they only ask for the EIC number!! So your right, the only copy(s) are held by the Electrician and customer (if one is even supplied)lol. The only time SOME certs are checked is when you have your annual assessment.....and the assessor just asks to see cert No. xxxxx!! There is no policing at all but we all ready know this whole idea is a big pile of poo!!!lol

I must state that this is the way Elecsa do it...not sure if the others do it the same way??

 

[leascliffe]

I too am registered with Elecsa, I've just phoned them for advice and also NAPIT who the original installer is registered with. They both have the same complaints procedure laid down by the Government. The customer has to give the original installer opportunity to put it right (A.N. Other contractor cannot correct the original work at this stage). If the contractor does not reply, then a complaint must be sent in writing to the certification body, who will investigate and decide the outcome, in this case it seems the contractor 'could' be struck off, meaning they would struggle to re-register with any other certification body.

The customer is emigrating at the end of this month and intending to let their house, don't think this will be possible while the complaint is ongoing and only 100mA protection in place, oh dear!...