DIY consumer unit change

[BigRab]

Hi this is my first post here & looking for some advise. I have reaserched this quite a bit & have seen loads of people being shot down regarding DIY changing of a CU.
Im looking to change my old rewireable fusebox for a modern CU with RCD's. It would be a straight swap, no change of location etc. The property is a 3 bedroom semi built in the late 1970's. My background is a vehicle electrician of 15 years, i have always done my own domestic electrical work but have never undertaken a main CU change, only a garage unit when i rewired my garage.
I don't know all the domestic electrical terminology like bonding which i take to mean the earthing of all the pipework in the house to the CU ??
I have a few questions.
Firstly can I legaly do this work myself (i am in Scotland if that makes any difference).
I have read about the Ze testing, If i was to just swap the units over without this test or any testing what problems could i have after the change (assuming that i make all the connections correctly) ? I mean if everything appears to be working ok with the original fusebox how can it be less safe than before ?
I would be intending to upgrade the tails & add 10mm earthing at the same time. I have no problem with pulling the main fuse either to isolate the supply.
Please dont crucify me thanks.

 

[PrenticeBoyofDerry]

Firstly can I legaly do this work myself (i am in Scotland if that makes any difference).

It's not illegal to install one yourself

I have read about the Ze testing, If i was to just swap the units over without this test or any testing what problems could i have after the change (assuming that i make all the connections correctly) ?

Without testing you would never know if it is safe now, or if you have introduced a fault or something unsafe whilst replacing, also without testing you will not find out if a swap for a new RCD protected board would be possible without creating power loss.

I mean if everything appears to be working ok with the original fusebox how can it be less safe than before ?

It will not be less safe unless, whilst changing you introduce something through your work that then increases a risk. But just because it seems to be safe does not mean it is, I would suspect standing at the finishing line at the Boston marathon would seem a safe place to be!

I would be intending to upgrade the tails & add 10mm earthing at the same time. I have no problem with pulling the main fuse either to isolate the supply.
Please dont crucify me thanks.

It's likely that both main bonding 10mm and earthing conductor 16mm will need updating.
I will let others, nail you to the cross!

 

[EFLImpudence]

I don't know all the domestic electrical terminology like bonding which i take to mean the earthing of all the pipework in the house to the CU ??

Not exactly, so first problem.

Firstly can I legaly do this work myself (i am in Scotland if that makes any difference).

Legally, you can.
In England and Wales you must notify the appropriate authority before you start and it will be up to them whether they deem you competent.
I think it is similar in Scotland.

I have read about the Ze testing, If i was to just swap the units over without this test or any testing what problems could i have after the change (assuming that i make all the connections correctly) ? I mean if everything appears to be working ok with the original fusebox how can it be less safe than before ?

You won't know without testing. It may be dangerous now.

It may not be less safe if you do it correctly, it may just not allow the RCD to be closed.

I would be intending to upgrade the tails & add 10mm earthing at the same time. I have no problem with pulling the main fuse either to isolate the supply.

Why? to both parts.

 

[ban-all-sheds]

Hi this is my first post here & looking for some advise. I have reaserched this quite a bit & have seen loads of people being shot down regarding DIY changing of a CU.

Usually because they refuse to accept how much they need to know, and how much it is not just a case of simply bunging in a new one and screwing wires into the tops of MCBs and L&N bars.

Im looking to change my old rewireable fusebox for a modern CU with RCD's.

How many RCDs?

Not thought about an all RCBO design?

It would be a straight swap, no change of location etc

But now would be an excellent opportunity to make changes to your current circuit layout.

I don't know all the domestic electrical terminology like bonding which i take to mean the earthing of all the pipework in the house to the CU ??

Strike 1 - you should know.

I have read about the Ze testing, If i was to just swap the units over without this test or any testing what problems could i have after the change (assuming that i make all the connections correctly) ? I mean if everything appears to be working ok with the original fusebox how can it be less safe than before ?

Strike 2 - you must have the ability (knowledge and tools) to test your work.

I have no problem with pulling the main fuse either to isolate the supply.

Strike 3 - that can be very dangerous. It might be the last thing you ever do. It is seriously inadvisable.

Please dont crucify me thanks.

The thing is installing a new CUs is not a trivial job, and I can assure you that it involves knowing far more than you think it does.

Asking questions here can be a useful part of a learning process, but they are not a substitute for proper structured studying. The key term there is "learning process" - you cannot learn all the things you need to know just by asking questions here. It isn't structured enough - it won't provide you with a way to progress where each step builds on what you learned before.

You can't carry out a job of this magnitude by asking whatever random questions happen to occur to you. You've already shown that you have some dodgy misconceptions (bonding is not what you described above)- what if you get something wrong because you have no idea your knowledge is wrong? What if you miss something because you simply have no idea it even exists, and just don't realise you don't know it?

• //www.diynot.com/wiki/electrics
  
  
• //www.diynot.com/wiki/electrics:books
  
  
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/electricity.html
  
  
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/domesticinstallations.html
  
  
• http://www.tlc-direct.co.uk/Book/1.1.htm[/list]I suggest you get stuck into the last link right away - it won't give you design ideas, and unfortunately it doesn't refer to the current edition of the Wiring Regulations, but it's free, and will still give you a good grounding which you can augment with more up to date publications.

 

[Taylortwocities]

do this work myself (i am in Scotland if that makes any difference).
I have read about the Ze testing, If i was to just swap the units over without this test or any testing what problems could i have after the change (assuming that i make all the connections correctly) ? I mean if everything appears to be working ok with the original fusebox how can it be less safe than before ?

Ze is an essential, but not the only, test that you MUST do.

The basis of this test (together with ones that you don't yet know about) will be to ensure that the new shiny MCBs will trip if you get a fault.

If the Ze is too high then Zs will be too high (look it up) and the MCB won't trip within the proper time period causing death, fire, pestilence and an outbreak of haggis.

You are planning to put in a dual RCD board.
A really important thing that you musty do is to test those RCDs.
Got an RCD tester? I thought not.

There's no point doing it AT ALL if you do not know what you are doing.

 

[17thman]

I see it this way. Whether you buy the materials your self or a sparky does, there is not much in it.

If you shop around you may get the job done for £200 Labour.

If you work for a living and you employ and electrician then you don't have to take a day off. If you plan to do it yourself on an evening or weekend then you may have an issue which will cost a lot of money to sort out at short notice.

Why on earth put your life at risk unnecesarrily for £200.00 quid?

How will you know your Ze and Zs are low enough. ow will you know your RCDs work? What will you do if one of your RCD's is tripping, leaving you with no lighting on the stairs?

In your fifteen years of vehicle electrical work have you ever seen a disaster caused by someone that thought they knew what they were doing?

Are you really going to pull the cut out fuse without permission or proper PPE. Would you pull the relace the cut out fuse under load?,for instance.

 

[Taylortwocities]

What he said^^^^^^^^

Plus: Please note PPE to wear when removing service fuse.

BTW, you are breaking the terms of your supply agreement with the electricity company if you do this.

Untitled

• Taylortwocities
• 11 Jun 2011
• 8

EDIT. Not sure if that jacket is kosher.....

 

[AdamCH]

Plus: Please note PPE to wear when removing service fuse.

I don't think I'd be tempted to pull a main fuse after seeing the British Gas fitter nearly cr@p himself when he tried to pull the fuse on mine. Togged up like darth vader, gave it a careful pull and then called Western Power to do it for him.

Turns out he had a colleague who'd had one explode & put him in hospital with face burns, even wearing the kit it's not risk free. The Western Power guy was a bit braver but also very careful also had a colleague who'd had one blow up on him and put him in hospital.

Seems if you pull enough fuses then one day .....

 

[Scoby_Beasley]

Seems if you pull enough fuses then one day .....

Bit like an anti win the lottery> every go you have lessens the odds, but who know when the 13+million:1 will hit?

 

[PrenticeBoyofDerry]

Not sure if that jacket is kosher.....

Doesn't look like a Rabbi would eat it! BigRab might though!

 

[ericmark]

I think the problem is MCB. With the fuse if the loop impedance is a little high then it just takes a little longer for the device to auto disconnect. But with the MCB there are two deices in one a thermal one which will in the fullness of time disconnect and a magnetic which will disconnect within a fraction of a second.

But for the magnetic bit to work enough current must flow. For example a B32 MCB needs 5 x 32 = 160 amp to flow. The impedance needs to be less than 1.44 ohms for that to happen.

There are auto electricians and auto electricians it's a wide subject and those working on trucks like the Electro-haul likely know more about high voltage than the normal house electrician seem to remember 10,000 volt but in the main auto electricians don't work with even low voltage and the problem is ionisation of the atomosphere rare but when it does happen leathal.

To me the big advance was the clip on ammeter. By ensuring no current flow one reduces the risk of ionisation but when I worked on auto electricis the Hall Effect meter was rare and most the clip on meters would not work on AC.

Also the leads were not fused, did not have finger sheilds, has more than 1 mm metal showing and were just not suitable for low voltage (230ac) work.

I am sure it will not matter what we say you will still do it. However I would try and borrow some test kit.

 

[securespark]

causing...an outbreak of haggis.

Nom!

 

[OwainDIYer]

As far as I know I've not blown a house up yet.

You been working in Callander recently?

 

[Scoby_Beasley]

As far as I know I've not blown a house up yet.

You been working in Callander recently?

Never been there. Never heard of it. Don't know what you're on about guv!

 

[ban-all-sheds]

That's what happens when you try to build houses out of cunningly arranged laths made of timber with 10 growth rings per inch.