New CU and meter tails etc

[brianmoooore]

Why are you changing the CU anyway?

Haven't you seen the pic? It's an ancient rewireable Wylex, with a fuse cover that's missing/unfittable. On the plus side, it isn't plastic.

 

[Vortigern]

Yes I have seen the pics. I am still interested from the OP as to why he has decided to do this. Personally on a pragmatic level, I wouldn't mandate a CU change on the box alone anyway. Significant improvements to safety could be achieved by doing so it is true. I was really wondering did the OP think this up all by him/herself or was it recommended by someone and if so why.

 

[rajshar]

Vortigern, first why changing the CU. No we aren't changing the CU, we are fitting one because currently we have old fuse box without any RCD protection.
About BG, yes few others have mentioned to go with either Hager or wylex. I am leaning more towards Wylex as with 7 RCBOs the price is just about £100 more. Although I am fully aware that even the best can fail too.

The reason I keep asking about the earth cable is that both electricians who gave quote and searching on Google it comes up that earth cable should be 10mm with 16mm tails or 16mm with 25mm tails. Both recommended changing it although one agreed to do it, the second one said he himself won't do it as it is the distribution networks responsibility. I am just trying to ascertain if it really should be upgraded and if yes then what is the best way to do it. I mean an electrician or the DNO.

Another confusion is that do we still need bonding as water gas supply is in plastic pipes. I just found a special note on the back of water meter booklet. I am attaching the picture of it here. I again don't understand that are they talking about main earth or bonding.

 

[rajshar]

The decision to change to a CU was taken after advice by a former electrician who is my colleague in the railway. We wanted a new circuit in the kitchen and I asked him, how to do it. He asked about the current equipment and then advised to upgrade to a CU. The reasons were given that new circuit in kitchen is notifiable and has to be protected by a RCD and it was best to do the complete upgrade rather than just doing a partial work. Unfortunately he can't recommend an electrician as he isn't from London, so don't know anyone locally. There is another compelling reason. When we bought the house in 2005, we weren't aware about electrical report neither it was mentioned to us by the surveyor and the electrical installation in my home never has been tested. We never had any issues though apart from a one time blown fuse incident due to a faulty socket. That's why we changed the lighting and socket circuits to plug in wylex mcbs. Since then no blown fuse or no tripping of mcbs. I take the wiring is in good condition. At least it has given me an opportunity to educate myself about regulations.

 

[SJD]

If the earthing cable is undersized when I'm installing a new (domestic) consumer unit, I generally just change it if practical & safe to do so, I don't start arguing over who owns which bit, I regard it as part of the job.

 

[Midwest]

If it was my house, I would spend my money on upgrading everything, new CU including RCBO’s, SPD’s, main earth, tails and anything else I could think of.

Which might include a rewire or partial rewire, which is when I might consider an EICR. But then sometimes, just a visual inspection would help you make that decision.

 

[rajshar]

I agree that while upgrading the CU, other cables including earthing and bonding should be upgraded too. That's why I asked it here. I have read some other posts from past in a very similar position and majority advice is that either there should be proper calculations to see if a 6mm earth will suffice or just upgrade to at least 10mm earth as a rule of thumb.

Do you still need bonding in the house when outside water and gas pipes are plastic but inside the house still copper?
Who should replace the earth cable from cutout to CU?
Does one need an isolator inside the CU when a 100amp isolator is fitted outside and if yes then what rating it should be inside the CU?

On closer inspection I found that earth cable is going into a small square size block moulded on the left side of cutout. This blocks cover is being held by a sealable screw. The "do not remove" seal isn't on this earth cable as I thought instead there is silver cable which come out of cutout, and goes underneath into this small block. The earth cable from top of this block goes to fuse box routed behind the ply board. Then another earth cable comes from fuse box for binding to gas pipe and continue on the gas pipe into kitchen under the floor, possibly to the water pipe and hidden out of site. I believe I should be able to unscrew this cover to have a closer look. Could it be the earthing terminal inside this block?

Just found this link in UK power network's site. Can I ask them to inspect the earth cable by requesting a visit or is it unnecessary. I don't know if they will charge a fee if they do any work but the visit and assessment is free.

Earthing | UK Power Networks

Is there an issue with the earthing at your property, do you need PME at your property or you don't have any earthing at all? Get advice now.

www.ukpowernetworks.co.uk

Thanks

 

[rajshar]

The sealable screw isn't sealed on this earth terminal block or whatever it is called. I unscrewed the cover and took a picture. It seems that any electrician should be able to change the earth cable as the green yellow cable is just connected to the too of this block. The DNO's earth connection with do not remove seal goes to the bottom of this terminal block and doesn't need to be touched. I personally feel it is dead easy for any electrician to upgrade the earth cable here unless there are some caveats to it.

 

[nicebutdim]

It seems as though the first electrician meets your requirements, other than the fact that you've expressed a preference for having a different brand of CU fitted. Why not just ask him for an ammended quote to account for this?

 

[rajshar]

Now before someone condemned me for doing this,vI would like to clarify. I k

It seems as though the first electrician meets your requirements, other than the fact that you've expressed a preference for having a different brand of CU fitted. Why not just ask him for an ammended quote to account for this?

I have asked him if he can provide me a quote either with a wylex cu or deduct the amount of cu and rcbos and I will supply him direct. I have given him the links of TLC for this, not sure if he shops at TLC. I have a TLC store about 2 miles from my home and can pick up the stuff in about 20 minutes.

Sorry to be pandentic but can someone advise me about isolator and it's rating in the consumer unit when a standalone isolator of 100amp is installed before cu or it doesn't matter as these are just main switches and they don't trip on their own and one can have multiple of them.
Also the requirement for bonding when outside supply pipes are plastic.
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