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]

Just to add that the reason he give me quote for labour work is because I asked him to fit Type A and B curve Wylex Rcbos. As he normally installs BG boxes, he said I should purchase whatever I want and he will install it. He is working with my neighbor, doing electrical work on council properties, so I know he is legit. But I don't know if he just avoiding the extra work of changing earth bonding etc or he really isn't allowed to do that.

 

[rajshar]

Sorry another correction. The earth cable from cutout is going to the fuse board not the bonding. So my electrician surely can upgrade the earth bonding from the new CU if not from cutout. This raises another question that in the last two years has and water pipes were changed to plastic at the street. From the street it still old water pipe which is lead and the plastic gas pipe was inserted in the existing metal pipe up to the gas meter. Gas meter is only 3 feet away from Electricity meter. Do I still need earth bonding?
Thanks

 

[buzzlightyear]

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.

the sparks that going to do the work does that include a EICR first before the work is Done.

 

[buzzlightyear]

Just to add that the reason he give me quote for labour work is because I asked him to fit Type A and B curve Wylex Rcbos. As he normally installs BG boxes, he said I should purchase whatever I want and he will install it. He is working with my neighbor, doing electrical work on council properties, so I know he is legit. But I don't know if he just avoiding the extra work of changing earth bonding etc or he really isn't allowed to do that.

Is the spark working for some one or working for him self, if working for someone their company might not cover them for working on the side. The questions I would be asking.

 

[Midwest]

Why should someone have to pay for an EICR, and then an EIC for a CU change?

 

[Strima]

This work is notifiable under Part P, any electrician who is a member of a scheme can notify for you if they're registered to do so.

From the service head to the meter is not your responsibility as this equipment belongs to the DNO and your energy supplier, from the meter is up to you to maintain. As you're getting an isolator switch fitted your electrician can connect from that, the person fitting the isolator should inspect their equipment before any work is carried out by them to ensure it is safe to do so.

You appear to only have bonding connections to the gas/water and no main earth? Can you post an overall picture of your equipment from the suppliers head to your distribution board?

 

[Mike Johnson]

Earth connection from the service head shown in Pic one and two, don't know where it goes too though, or where what I assume to be bonding on the Water pipe?

 

[telectrix]

tails from cut-out to meter are the responsibility of DNO. (SSE?).
nothing wrong with a BG board with their compact RCBOs.
upgrading main earth is no problem for a sparks.
bonding cables are for your sparks to upgrade if required.

 

[westward10]

There is a braided earthing conductor with a "Do Not Remove" tag over it into the bottom of the earth terminal.

 

[rajshar]

In response to buzzlightyear. Thanks for your reply.
I don't know if he is going to do EICR before doing any work but as I remember our conversation, EICR was never mentioned. He did say EIC after the installation and test. Again I don't know which test/tests will be done.

My next door neighbor is a builder working for the council and renovating the council properties from scratch. This electrician is his friend and also does the work for him. I don't know if he is independent or working for a firm. I'll surely ask more questions. I have seen his work next door and that seems fine to the naked eye.
Thanks

 

[rajshar]

Thanks Strima, telectrix and westward10.
I thought the earth cable from cutout with the tag "Do not remove" is the main earth and it is going in to the fuse board, routed behind the ply board. My understanding is that my electrician should upgrade the tails to 25mm from the meter to CU, regardless what is from the cut out. He should also be able to upgrade the earth bonding from the CU to gas/water pipe provided I still need it as the street pipes are plastic.

What can I ask the suppliers electrician other than his usual work of fitting an isolator. Obviously he is going to take the fuse out for a safe work environment. If I supply him the tails and earth cable, can he change them. Obviously a lot will depend on his mood and schedule.
Here is the pic as requested.

 

[rajshar]

Just realised that If an isolator is fitted then my electrician can't change the tails from the meter, he can only change from the isolator. So now definitely I will have to ask the supplier's electrician,vif he can upgrade the cables. I will get the cables anyway, whether he does or not.

 

[rajshar]

Thanks Mike Johnson. That earth cable from cutout is going in to the fuse board and then another one of same size comes out up to the gas pipe. From this joint of gas pipe it just goes underground to the kitchen, possibly to the water pipe.

 

[Strima]

The installer who fits the isolator should fit the correct size tails, but they may only do this from the meter.

This diagram shows you who is responsible for each bit, it's taken from a DNO guide:

 

[rajshar]

Thanks Strima.
The suppliers installer will fit the correct cables if he deemed necessary. between meter and isolator and between cutout and meter as anything after cutout to meter is the suppliers responsibility.

Now I could be completely wrong but isn't that with a 100 amp fuse the 16mm tails aren't suitable as they have maximum rating of 80amp. We had smart meter fitted April 2020. I am just wandering that why they didn't upgrade the right tails or downgrade the cut out fuse that time. That time I knew nothing about any standards or regulation otherwise I would have asked the installer for this and would have arranged for an isolator at the same time.
The other issue is the earth cable. Now we don't have the earth conductor or earth block. The earth cable goes direct to the fuse board from cut out. The current earth cable doesn't comply even with 16mm tails. I believe it should be 10mm in the current settings and if upgrading to 25mm cable it should be 16mm. Even this wasn't pointed out to us by the meter installer. May be it's not their job to change the cables but at least during the installation, they should be inspecting that equipment is in compliance. Or is it that my equipment is still in compliance because new regs don't apply retrospectively. Anyway when suppliers installer comes to fit isolator and decides that 16mn tails are good enough, shouldn't then who ever is responsible, change the cut out fuse to the correct rating. Although upgrading the tails should be the best option.

Now some electricians have no problem to upgrade the earth cable and some just getting out of it by saying they don't touch the cutout as this 2nd electrician said. It also makes me wonder that how he was going to change the CU without any isolation because he didn't knew that I had arranged for an isolator to be fitted. I think I should at least ask one more quote and see what he/she can or can't do.

All this brings up new questions. All the CUs come with 100 amp isolators. Do we still need an isolator inside the CU, if one fitted outside, if yes should it be lower rating than the 100amp?

Thanks.

 

[brianmoooore]

100A is the max. rating of the cutout fuse holder. 100A fuses were common several years ago, but the DNOs have been changing them to 80A when the opportunity arises on 'normal' supplies.

 

[rajshar]

Earlier telextrix said that BG CUs are good. Sorry I didn't meant that BG boards are bad. It's that he was going to get the BG CU from Screwfix and all the prepopulated BG CUs with RCBOs they sell come with Type AC RCBOs. I want Type A RCBOs and I was thinking to get the wylex ones from TLC. Anyway now I found that TLC does sell BG brand Type A RCBOs as well and it comes around £107 pound cheaper than Wylex, it's not that big difference.. Now it's just a struggle to chose between Wylex and BG.
Thanks

 

[rajshar]

Thanks brianmooore. So do you think that when smart meter was fitted, they would have changed the fuse. Do they not put any notes etc about the rating of the fuse as I don't see anything to indicate. Do you think that someone should have pointed out that earth cable needs changing.
Thanks

 

[Vortigern]

It is not necessarily the case the earth cable needs changing. The braided earth is supplied from the DNO and it is their equipment. The energy supplier (in theory) should not touch the DNO equipment and vice versa. It depends on the fault current likely to occur at the CU. Personally I would not fit BG my experience with them has been they are unreliable and I have had quite a few failures with their RCBO. The earth cable from the DNO supplied earth to the CU can be changed no problem but then there must be a reason to do so such as thermal damage for instance. Why are you changing the CU anyway?

 

[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

 

[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.

 

[Midwest]

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

Most CU changes don’t warrant an EICR beforehand. When I did CU replacements, I tested all the circuits before the old CU came off the wall. That was part of my pricing for the CU replacement.

IMO an EICR (before a CU change) is only necessary with a large property, or one where there is concern over of the condition of the installation. For example, I’ve had to replace the CU in my house, which is just over two years old. It would of been completely unnecessary to carry out a EICR beforehand, if I had been paying someone to do it.

 

[DPG]

The guy who told you he would take the RCBO out and replace it with an MCB if it kept tripping - you don't want him doing any electrical work in your house if that is his outlook on things.

Also, I would recommend having an SPD. Makes sense to have one now while the work is being done. Cost is minimal and it seems wise to be on the safe side. Never assume equipment is immune to surges and spikes. A company i know of once removed surge protection devices on some of its products, and guess what happened to the returns figures?

And it's not just lightning strikes that cause these spikes.

 

[nicebutdim]

Most CU changes don’t warrant an EICR beforehand. When I did CU replacements, I tested all the circuits before the old CU came off the wall. That was part of my pricing for the CU replacement.

IMO an EICR (before a CU change) is only necessary with a large property, or one where there is concern over of the condition of the installation. For example, I’ve had to replace the CU in my house, which is just over two years old. It would of been completely unnecessary to carry out a EICR beforehand, if I had been paying someone to do it.

If you were replacing a BS3036 board like that in the OP's images, rather than something of recent vintage, how might you approach the task?

 

[Midwest]

If you were replacing a BS3036 board like that in the OP's images, rather than something of recent vintage, how might you approach the task?

I would go to the house and have a look to the installation

 

[rajshar]

I found shortcomings from both electricians, so I am not going ahead with any one of them.

One was the attitude to replace RCBO with MCB if fault can't be rectified, instead he should have said that we must rectify the fault as that can be dangerous.

The second one is the earth bonding. When I told him that the supply pipes are plastic up to the house boundary he said he will leave the water pipe but he will upgrade the bonding to gas pipe anyway.

Strima said that you guys will calculate in this scenario if bonding is required. I read about bonding in the following article.

https://electrical.------.org/wiring-matters/years/2018/73-november-2018/myth-busters-2/

So it certainly makes a case to do proper assessment and calculation and then bond if required. So that is another thing

I will take few more quotes now because now I know what should I ask. I am fairly sure that old cables and sockets(MK brand) are in very good condition. The only sockets which I have doubt are relatively new ones fitted in the kitchen during kitchen refit about 9 years ago. They are of Lap. One was causing sparks during on/off and blew the fuse. I have changed 3 single Gang sockets with Schneider sockets. I will replace the other sockets in the kitchen too. Is Schneider fine or should I get the MK brand sockets.
May be I should just get an EICR first and if there is a need for rewire then sort that first at the first opportunity and then at the same time do the CU upgrade. If no faults then just do the CU upgrade. The new circuit in the kitchen can wait until that time.

Btw, a lot of you are emphasising on SPDs. I am still not convinced of their benefit in an average city house. Anyway if one has to go with SPD then is it allowed to mix different brands in a CU or not. I know you can't mix different brands RCD/RCBO/MCBs. Whatever make is the CU, it should be the same make components. So is it same for SPDs. I am asking this because there is huge difference on price of SPDs between different Makes?
Should I also go with AFDD as that provide additional protection too?
Thanks for all your help