Replacing an old CU with a new one

[Naz1977]

Having had to get an electrician involved to replace my CU, as per advise from here and everyone jumping on my back, here is my experience with the so called electrician that came around:

Arranged for my CU to be replaced at the cost of £250 provided I supplied the CU and breakers and ...
CU is a MK item, with no breakers/MCBs/RCDs at all,
Set of Schneider Electrics MCBs/RCDs different ratings based on the advise from him as what I needed

He turned up. Got the feeling he didn't really want to do the job as he had already rescheduled it once.
Anyway, turned power off,
Took the front off
Then said to me that the tails from the meter to the CU were not big enough and needed upgrading. These are 16mm tails.
My current setup is as follows: From Meter to Fuse, then from Fuse to a Voltlage operated breaker, then from the breaker to the switch inside the CU. Meter was replaced by the board about 4 months ago and they upgraded the internal fuse that was installed at the time.

So anyway, he said he can't replace the CU as the tails need replacing and since it is the tail from fuse inside the meter cabinet to the CU, he can't touch it and it has to be the board. he would raise this with them and get them to come and replace and then he would replace the CU

As he was there, I told him I wasn't happy with my electric shower being connected to an MCB and would rather that was connected to an RCBO to give me better protection. He then went and bought an RCBO and came and replace it. At the same time I asked him how much he would charge for a EICR and he said he charges £50 for the report and with the RCBO he would charge me £100 for it all

I agreed, and he proceeded to do the test. Which took him about hr and a bit. He then took his money and said he would send me the report and certificate

3 weeks went past and I didn't get anything from him.

So emailed him and he said that he wasn't happy to send me the EICR as he had come across an issue in his report to do with the bonding to the earth spike outside my house.

As it is a TT install, obviously I supply the earth for the installation. And as it was, the boding used a 6mm cable at the moment and he said this is not adequate and needs to be replaced with a 10mm bonding to the spike and unless this is done he is not going to send me the EICR.

I emailed him back and explained about my understanding of the EICR that it is a report and not a certificate as such which gives me details of any issues with my installation.

He then didn't come back to me and wouldn't respond to my emails.

Having send him a final email and explaining that I will be taking this matter further if he doesn't come back to me with an answer, he emailed me back saying:

He will send me the EICR report soon
He has said that the boding needs replacing as this is a fire risk at the moment as it is using 6mm cable
He now says the 16mm tails are ok and don't need replacing.
He says he wasn't happy to replace the CU as the CU and the breakers have to be the same make, according to BS 7671 2008+A3



So I get a feeling that I have been taken for a ride and would appreciate your feedback as regards to :

1) If he says boding is a fire risk, then should he have replaced the MCB with RCBO as he has made alterations to my CU/installation by doing so, or should he have left it untouched and simply said no can do.
2) Is he right about the CU and the breakers? My understanding is that you can't mix and match the breakers inside the CU but not that the CU and breakers have to be from the same manufacturer?
3) the house is a bungalow at the moment with only 2 bedrooms. But there are plans to extend to 4 bedrooms and turn into a house. He now says the 16mm tails are ok for the current installation, but when in future, we are talking about perhaps 12-18months time, when I come to install new circuits, the 16mm tails are not good enough.


I shall await the EICR and see what it says, I can then check with NICEIC to make sure he is indeed registered with them as I can smell b***** in some of the things he said.

Thanks

 

[333rocky333]

Why was the CU mk and the breakers schneider.
Yes they should match.
As a last resort if it was a fairly old existing Mk sentry CU whick mk no longer make parts for, that used the same profile Mcbs as the current merlin gerin at the time, that the current schneider also fit.
However there is no justified reason not to use all matching parts on a new install

I dont do TT work
But I think you may find that bonding should be 10mm , but the cable to the rod is NOT bonding that I think is called an earthing lead and Im sure should be bigger maybe 16mm

 

[securespark]

Last I looked the cable to the rod on TT could be as small as 2.5mm² with mechanical protection?

Why should an EICR be withheld because there are perceived defects?

It appears he knows very little.

When he says "boding", does he mean the cable to the rod?

If so, ask him to work out what the fire risk is.

 

[Naz1977]

According to him, it is a fire risk should a fault occur?

As for the bonding, yes, he meant the earth cable that runs from the CU to the rod.

Can someone confirm if it definitely a no no to put someone else's MCBs into another make's CU?

The CU I have is a MK unit which I bought as a bare unit. it is a metal unit, confirms to the latest regs and as I have an electric account with screwfix, I got a good deal on it. I couldn't find a CU pre fitted with MCBs to the spec I wanted, so went for a bare unit . The MCBs are all Schneider electrics and the profiles and busbar fitment and din rail is the same. Isn't a CU at the end of the day only a housing? I can't understand that he says it can't be done, yet still he goes and buys a RCBO which is diffrent to the make of my current CU and fits it?

 

[flameport]

1 - 6mm bonding or 6mm earthing is not a fire risk. 10mm is the usual size for main bonding on new installations mainly because that is the minimum size for TNCS supplies - it can be smaller for TNS and TT.
The main earth would usually be larger than 6mm, often 16mm is used, but that only applies to TNCS/TNS systems. The main earth can and often is much smaller for TT.

2 - The CU and devices inside should be the same manufacturer, so (2) is correct.

3 - Whether 16mm tails are suitable depends on the total expected load. It's exceptionally unlikely that a domestic house would require larger ones, although 25mm is often fitted on new installations.

An EICR is just a report, it's contents have no relevance to whether it is provided or not. It isn't something which has to say 'all is well' - it could equally say the entire installation has hundreds of defects and is a serious hazard to anyone who goes near it.

It's not necessary to be registered with the NICEIC or any other organisation to issue EICRs.

 

[flameport]

Isn't a CU at the end of the day only a housing?

It is, however to allow consumer units to be sold as complying with a particular standard, they have to be tested and type approved as a complete assembly, and obviously they are only tested with devices from the same manufacturer in them.
Using devices from other manufacturers means the complete assembly doesn't comply with the type approval, and therefore doesn't comply with the standard either.

In reality if the devices fit properly there is unlikely to be any problem.
However there is really no reason to not use devices from the same manufacturer unless they are no longer available, discontinued, etc. as may occur with very old types.

Although many MCBs etc. from different manufacturers are the same physical size, there are plenty which are not.

 

[ban-all-sheds]

Having had to get an electrician involved to replace my CU, as per advise from here and everyone jumping on my back, here is my experience with the so called electrician that came around

Hands up all those here who thinks that Naz chose the cheapest electrician he could find.

 

[Naz1977]

The advise from here, and mainly yourself, was to get an electrician to do the work and don't attempt it myself.

The whole point of getting a few people to provide quotes is to find the cheapest person to do the work.

Cheap doesn't mean necessarily bad, as competition brings prices down.

Do you not go to price comparison sites and change your gas and elec supplier to the cheapest one? It is the same. why should I not use the cheapest leccy?

If you are all ( leccys that is ) covered by the same guidelines and rules and regs to follow, then why should it matter who I use? The chap was on mybuilder.com and apparently with 17 years experience!

 

[securespark]

BAN; Because (if that were true) that would please you as you could then make a point?

There are plenty of not-cheap sparks who don't know their stuff; they do things a certain (and often incorrect) way without questioning it because that is how they were taught.

 

[Naz1977]

1 - 6mm bonding or 6mm earthing is not a fire risk. 10mm is the usual size for main bonding on new installations mainly because that is the minimum size for TNCS supplies - it can be smaller for TNS and TT.
The main earth would usually be larger than 6mm, often 16mm is used, but that only applies to TNCS/TNS systems. The main earth can and often is much smaller for TT.

2 - The CU and devices inside should be the same manufacturer, so (2) is correct.

3 - Whether 16mm tails are suitable depends on the total expected load. It's exceptionally unlikely that a domestic house would require larger ones, although 25mm is often fitted on new installations.

An EICR is just a report, it's contents have no relevance to whether it is provided or not. It isn't something which has to say 'all is well' - it could equally say the entire installation has hundreds of defects and is a serious hazard to anyone who goes near it.

It's not necessary to be registered with the NICEIC or any other organisation to issue EICRs.

It is a TT system, so theoretically the fact that says according to him the installation is not safe and a fire hazard due to using a 6mm cable and not 10mm is total rubbish?

As for the tails, I just get the feeling he didn't want to do the job, charged me £100 for doiing not much and buggered off with nothing left for me.

 

[Naz1977]

It is, however to allow consumer units to be sold as complying with a particular standard, they have to be tested and type approved as a complete assembly, and obviously they are only tested with devices from the same manufacturer in them.
Using devices from other manufacturers means the complete assembly doesn't comply with the type approval, and therefore doesn't comply with the standard either.

In reality if the devices fit properly there is unlikely to be any problem.
However there is really no reason to not use devices from the same manufacturer unless they are no longer available, discontinued, etc. as may occur with very old types.

Although many MCBs etc. from different manufacturers are the same physical size, there are plenty which are not.

I don't know if you are a sparky or not ? However if you are, and you went to install the above, would you refuse to install or would you be happy to install provided the units and the CU fitted with no issues?

 

[flameport]

I would not install any consumer unit provided by a customer, regardless of what devices it contained.

 

[flameport]

Do you not go to price comparison sites and change your gas and elec supplier to the cheapest one? It is the same. why should I not use the cheapest leccy?

Gas and electricity are exactly the same regardless of who you pay - in that instance it makes sense to choose the cheapest supplier.
People working in your house is not comparable, as different people will have different levels of competence including excellent, totally useless and everything in between.

Cheap doesn't mean necessarily bad, as competition brings prices down.

Up to a point - beyond which some people will make a job cheaper by not bothering to do certain things.

 

[333rocky333]

Im confused, if he says he will get the board to come and change the meter tails, i assume he did not want to ilegally break the seal.
If all the materials had been suitable how did he propose to isolate the supply to fit this new metal board

 

[Naz1977]

Gas and electricity are exactly the same regardless of who you pay - in that instance it makes sense to choose the cheapest supplier.
People working in your house is not comparable, as different people will have different levels of competence including excellent, totally useless and everything in between.


Up to a point - beyond which some people will make a job cheaper by not bothering to do certain things.

ok, he quoted me £350 to replace the CU. The other one quoted me £450 as said he would have to notify the council. However I told him he didn't have to as I had a building work going on and council was already aware and all he had to do was to provide a cert to me. First one said fine, second said no he still needs to do it and hence the charge of £450. So I went with the first one.

As mentioned before, I used to work as an apprentice leccy and would have been competent enough to replace it. And then would have had someone to do an electrical test on it and provide an EICR. If you buy a new house, all you can do is to get an EICR done and then act on that if anything is wrong. This is the same, isn't it? Leccy won't come and say to you when you buy a new house that he can't do an EICR on it as he didn't do the wiring!

If I do a job, at least I know what I have done and as it is on my own house I will be neater and done with more care than when it is working on someone else's house.