New CU and meter tails etc

[rajshar]

Hi
I don't know if I should ask it here or the main electricians forum. It's about CU change and the work around it and the CU change will be done by a proper registered electrician.

I will try to upload the pictures so you can see what I am talking about. I took two quotations. One just ask for pictures and quoted me for new BG CU with RCBOs, meter tails, upgrade the earth cable as the old one is only 6mm.

The second one visited my house today and after looking at the meter fuse board gave me two quotes, one including materials and one just his labour, testing and certificate charges. He said there is no need to tell Building control as he is registered and his certificate covered it. His quote includes fitting new CU and meter tails. But he said he won't change the earth cable as that is coming out of cut out and he isn't allowed to touch that. He also told me that the tails from the cutout to the meter and then to the fuse board are 16mm. The cutout fuse is rated 100A. The length of tails from cutout to meter is about 60cm and from meter to the fuse board is about 120cm including all the bends. Is all this acceptable? I know that I can ask him to fit 25mm tails to the CU but who is responsible to change the tails from cutout to the meter and who is supposed to change the earth cable for bonding from cut out to the gas pipe.

I have an appointment scheduled with British Gas to fit an isolator between the meter and fuse board as the first electrician asked for it. Can British Gas electrician change the tails and earth bonding cable from cutout while fitting the isolator?
Sorry for a long description and questions.
Thanks

 

[rajshar]

I think I was writing something else and it went in on the top of last reply. I was just trying to say that I made sure I was doing it safely while unscrewing the earth block.

 

[telectrix]

any electrician can change that main earth conductor. as you say, main switches are usually 100A. both in isolator and CU.

 

[rajshar]

any electrician can change that main earth conductor. as you say, main switches are usually 100A. both in isolator and CU.

Thanks. So it seems to me that the first electrician is the right person for the job. I was just reluctant that he quoted me without a site visit. May be the pictures were good enough to give him the idea about the state of wiring.
Thanks for your help in clearing few doubts and to take a decision.
Cheers

 

[Strima]

As you have mentioned there are requirements for the sizing of the main earthing conductor.

The bonding conductors also need to be sized correctly. As a default we used to bond all services (water/gas etc), but recently this requirement has changed and we now test to see if an earth potential is introduced through your service pipework.

If there's no earth potential then it doesn't require bonding. If there is a potential then we bond it.

This recent change is due to the increased usage of plastic service pipes.

 

[Vortigern]

It's all very well quoting by sight on a new CU but when it comes to fitting and all the RCD are popping off becuase there are faults on the circuits on the new RCD are you ready to fork out on fault finding which is sometimes very expensive? This is why an EICR is offered first to identify faults before hand. If not then it's a bit of a shot in the dark and you may get into some expensive costs. Sometimes it is easier and cheaper to re-wire than look for faults which may or may not be able to be corrected. I should proceed with caution were I you.

 

[rajshar]

As you have mentioned there are requirements for the sizing of the main earthing conductor.

The bonding conductors also need to be sized correctly. As a default we used to bond all services (water/gas etc), but recently this requirement has changed and we now test to see if an earth potential is introduced through your service pipework.

If there's no earth potential then it doesn't require bonding. If there is a potential then we bond it.

This recent change is due to the increased usage of plastic service pipes.

He told me no need for water pipe bonding. The gas pipe he is going to bond with 10sqmm cable. I have informed him that the gas pipe outside is plastic but he is going to bond it anyway. May be he doesn't want to spend time to test and calculate and it is much easier just to bond.
The only issue is the isolator switch now. British Gas has just started doing the work which was suspended due to covid. The appointment is on 15th of April which is quite far away. I certainly don't want him to pull the fuse, so may have to wait a while.
Thanks

 

[rajshar]

It's all very well quoting by sight on a new CU but when it comes to fitting and all the RCD are popping off becuase there are faults on the circuits on the new RCD are you ready to fork out on fault finding which is sometimes very expensive? This is why an EICR is offered first to identify faults before hand. If not then it's a bit of a shot in the dark and you may get into some expensive costs. Sometimes it is easier and cheaper to re-wire than look for faults which may or may not be able to be corrected. I should proceed with caution were I you.

I raised this issue with him and he said that MCBs should be fine as we already have plugin MCBs without any issues. If RCBOs start showing some faults as they are more sensitive then either we rectify the relevant wiring if feasible or he will take the RCBO out and fit the MCB. I am not satisfied with this response. What is the point of upgrading if a MCB/Fuse is going to replace a MCB without a RCD. We certainly won't be able to chase any new cables downstair because of tiles and laminate floor. Even the new circuit in the kitchen is going to run under the kitchen cabinets until the next kitchen refit.
What do we need to do before the install? Would an EICR highlight any potential faults. I am just double minded here. One is that there shouldn't be any issue as we never had any problems and the wiring seems to be in very good condition. All the old sockets switches are in perfect order. I have seen myself the state of wiring in some houses, which I won't describe as adequate or safe. The only sockets with problems were the new ones, fitted during kitchen upgrade. The other one is, What If this happens or that happens. As I have more time, I will discuss with him in more detail. Btw any estimate for EICR because if I insist for one before install, he certainly will charge me extra as that is extra time.
Thanks

 

[richy3333]

Wow this all comes over as more complicated than it need be

If the gas and water pipes are plastic coming in to your house then the chances are they dont need bonding. An electrician can do a simple test to decide if they are extraneous conductive parts or not. If not dont bond if they are run bonding cables.

We always update/upgrade meter tails and main earth conductor with a CU renewal as part of our price.

Testing should be undertaken before the swap to ensure the circuits are in good condition or not and if there are any potential problems.

BG equipment is awful, nasty cheap rubbish. If you want an economy board get a Fusebox board. Buy type A RCBO's. Dont get a split load board and get an SPD fitted. If you want something decent buy a Hager board.

EIC at end and I think in Englandshire building control notification

Maybe get a third price?

 

[pc1966]

I raised this issue with him and he said that MCBs should be fine as we already have plugin MCBs without any issues. If RCBOs start showing some faults as they are more sensitive then either we rectify the relevant wiring if feasible or he will take the RCBO out and fit the MCB. I am not satisfied with this response

You are right to not accept that response.

MCBs only pick up on over-current, they do not care about potentially dangerous mistakes such as:

• a N-E short
• swapped N &E at an outlet
• a "borrowed" neutral on up/down lighting circuits, or
• very poor/damaged insulation that is only a short journey from fire-starting.

The above should be apparent on testing, and really that ought to be done before you start so you at least have a good idea of the possible cost to put everything right. While some won't do a full EICR first, most sane electricians would do a little inspection and some tests first just so they can eliminate some of the above.

 

[rajshar]

You are right to not accept that response.

MCBs only pick up on over-current, they do not care about potentially dangerous mistakes such as:

• a N-E short
• swapped N &E at an outlet
• a "borrowed" neutral on up/down lighting circuits, or
• very poor/damaged insulation that is only a short journey from fire-starting.

The above should be apparent on testing, and really that ought to be done before you start so you at least have a good idea of the possible cost to put everything right. While some won't do a full EICR first, most sane electricians would do a little inspection and some tests first just so they can eliminate some of the above.

Ok so it makes sense to do EICR. I got nearly five weeks and will take up my concerns with him.
I was also of the view after reading other posts that I may not need bonding as pat1966 suggests.
Everything else is fine but SPDs don't appeal me. Again I have come to this point after reading some posts about them. One we don't get any lightning strikes here and never heard if anyone ever got one. Second if it happens in future then it will go out at first strike, then what happens on the subsequent second strike. Most sensitive equipment i.e. Computers, laptops, Led TV etc we already have surge protectors. White goods will be covered under insurance anyway. So I'll need much more convincing reason to go with SPD. May be when they can design one which trips and can be reset.
Thanks

 

[pc1966]

I'm not sure what you have read about the SPD, but they rarely cause trouble and these days most CU come with one as standard. Cost is modest, typically a few tens of pounds now, and compared to the whole CU change (or analysing risk for fitting or not) not worth omitting.

It is not always lightning spikes that can be a risk, it can be high current faults being disconnected.

For most of the time you ought not to need them as mains equipment is supposed to stand a few kV impulse voltage, but I would not put it past insurance companies to start weaselling out of claims if no SPD!

 

[Vortigern]

The idea that the solution to faults with RCBO be dealt with by replacing with MCBs is very poor to dangerous thinking/practice. Did he arrive on a horse by any chance?

If RCBOs start showing some faults as they are more sensitive then either we rectify the relevant wiring if feasible or he will take the RCBO out and fit the MCB.

 

[rajshar]

I'm not sure what you have read about the SPD, but they rarely cause trouble and these days most CU come with one as standard. Cost is modest, typically a few tens of pounds now, and compared to the whole CU change (or analysing risk for fitting or not) not worth omitting.

It is not always lightning spikes that can be a risk, it can be high current faults being disconnected.

For most of the time you ought not to need them as mains equipment is supposed to stand a few kV impulse voltage, but I would not put it past insurance companies to start weaselling out of claims if no SPD!

I agree with you that SPD gives an additional protection, but I am not convinced yet for their use in a home as a standard device yet. There is no case record to warrant SPDs at this time. As you said most of the mains equipment can handle some surges and the most sensitive equipment as computers etc, people do use surge protectors anyway. At least I do. The current faults can occur but I never experienced one . There could be scenarios, where SPDs are better suited.

 

[rajshar]

The idea that the solution to faults with RCBO be dealt with by replacing with MCBs is very poor to dangerous thinking/practice. Did he arrive on a horse by any chance?

You are right, it does create doubt in mind that's why I said that I am not satisfied by his response.

Right now as I have time, I'll surely take another opinion. I know everyone works differently and that's not a problem. It's just that I have taken two quotes and none of them mentions any testing prior to installation. I spoke with my colleague and even he said that pre install testing should be done because RCDs/MCBs are more sensitive and if there is any fault, they will become nightmare. Wired fuses are more forgiving but do increase the risk, so definitely need the upgrade. If no fault then perfect otherwise it will be an opportunity to put things right.

Btw which test is carried out to determine if bonding is required when there is no extraneous conductor.

I want to prepare myself with the right questions to ask this time.
Thanks

 

[rajshar]

Didn't see the edit option. Still learning about this forum.