Replacing a consumer unit

[paulp51d]

Hi,

I would like some basic advice on replacing a consumer unit. I am an electrical engineer, but not a qualified electrician, so I am not familiar with the regs, nor with working practices.

When replacing a consumer unit how is the incoming main isolated? Presumably it's not just rubber gloves.

My son knows an electrician who can test and certify after the event, but I am wondering if it's feasible to do this work myself?

Thanks

 

[1john]

You cant really do the job without the use of some proper calibrated test equipment. The installation needs testing beforehand to show up any herrings, red or otherwise. You may have issues with neutral to earth faults which will be very inconveinient when the consumer unit has been installed and you cant reset an RCD. You also need to check for borrowed neutrals on lighting circuits, and finally, the LABC fee's may cost more than getting a spark in.

 

[flameport]

t I am wondering if it's feasible to do this work myself?

Highly unlikely.

Replacing a CU is notificable work, which is likely to incur LABC fees of £100 - £300 in most areas.
Getting someone to test afterwards is no use, since all of the circuits must be inspected and tested before they are connected to the new CU.
For virtually all CU replacements, there will be other remedial works to do. These will probably take longer than replacing the CU itself.

 

[paulp51d]

OK thanks, comments much appeciated. An electrician it is then.

 

[Taylortwocities]

You'll need to use one that is registered to notify his own work.

Most of these are listed here
www.competentperson.co.uk

Type in your postcode. Get quotes from two or three.

 

[ban-all-sheds]

As ever, personal recommendations are always the best way to find a reputable tradesman, but if you're having to go ahead without much in the way of those, or references, don't put any store by registration itself - sadly it is possible to become registered with woefully inadequate qualifications and zero practical experience.

Like never having replaced a CU, for example.

You don't have to spend long here to see people cropping up who are registered and "qualified", but who are clearly seriously incompetent in reality and who should not be charging for their services.

It's your money, £'00s of it, and you have every right to ask prospective tradesmen what their qualifications are. Just being listed here is not a good enough guide. No genuinely experienced electrician, with the "full set" of C&G qualifications will mind you asking - in fact he will wish that everyone was like you.

I feel sorry for people who have been misled by training organisations and (shamefully) the Competent Person scheme organisers into thinking that a 5-day training course, a couple of trivial examples of their work and some basic understanding of how to use test equipment will make them an electrician, but not sorry enough to agree with them trying to sell their services to Joe Public.

 

[paulp51d]

Yes, thanks for the advice, but finding a good guy should not be hard.

Just by chance I am contact rich at the moment. My son is a plumber and they use a good spark, his girlfriend's dad is a builder, the kid across the road is a qualified electrician and another neighbour is an electrical contractor. They have to be good for at least one recommendation between them. Don't they?

 

[1john]

Ask about, get various quotes, dont use anyone willing to change the consumer unit, or even who insists on changing it without an inspection and testing beforehand, you could end up with a new consumer unit fitted with an RCD or two that wont set and a spark having to fault find at £xx an hour for an absolutly indeterminatable amount of time.

Make sure you main equipotential bonding is upto scratch, this is a job you can do yourself.

Also know what type of consumer unit you want installed, with the regs as they are there are many ways of acheiving the standard with hugly different costs and also different levels of inconvenience when something trips.

 

[paulp51d]

The reason I was thinking about getting a new CU is that the house currently has an old-style fuse board. My son and his girlfriend have only just bought the place and are in test and tear-down mode at present. They have yet to move in.

At the weekend my son turned on the emersion heater, which immediately blew a fuse that evidently was used for the emersion heater and the ring main. So, we had to go out and buy some fuse wire.

Being a plumber, he intends to get rid of the emersion heater and replace it with a combi-boiler, but that episode, plus some criminal wiring in the loft suggests to me that the electrics are in a mess.

With regard to RCD's in the CU, are you saying that these frequently introduce on-going problems? Can I get a CU without RCD's?

 

[electronicsuk]

With regard to RCD's in the CU, are you saying that these frequently introduce on-going problems? Can I get a CU without RCD's?

They only introduce problems with faulty wiring or appliances, and are worth fitting for the extra protection they provide. You could fit a CU without RCDs, but without rewiring the whole house in SWA, flexishield, earthed steel conduit or with all cables buried >50mm deep, it would be difficult to certify compliance with BS7671 or part P!

 

[ban-all-sheds]

And even then what about all of the sockets?

 

[ban-all-sheds]

The reason I was thinking about getting a new CU is that the house currently has an old-style fuse board.

Which probably means only a few circuits as well.

My son and his girlfriend have only just bought the place and are in test and tear-down mode at present. They have yet to move in.

There will never be a more convenient or cheaper opportunity to do a complete rewire, or add all the new circuits they might want, add all of the sockets and switches that they want, and so on.

The electrician will be able to make as much mess as he likes with chasing tools and SDS chisels without having to worry about soft furnishings, possessions and full-spec hoovering up each day. He won't have to worry about restoring power, moving furniture around, replacing floorboards etc. All of these things will shorten the job.

Your son and his g/f won't have to worry about mess and decorative damage, nor end up damaging their new hardwood/tiled floors, wallpaper etc in a year's time.


They should think hard about where to have sockets - it's difficult to have too many, and also about what circuits to have. The items on the list below won't all apply to them but they are worth thinking about:

• Upstairs sockets
• Downstairs sockets
• Kitchen sockets
• Circuit for appliances
• Cooker circuit
• Non-RCD circuit for F/F
• Non-RCD circuit for CH boiler
• Dedicated circuit for hifi
• Dedicated circuit for IT equipment
• Upstairs lights
• Downstairs lights
• 5A round pin sockets controlled by light switches for table/floor lamps
• Immersion heater
• Loft lights
• Shower
• Bathroom circuit
• Alarms
• Supply for outside lights
• Supply for garden electrics
• Supply for shed/garage

Plus any peculiarities brought about by the house layout & construction - e.g. in mine because of solid floors and where the socket circuits run, I have a radial just for a socket in the hall, the doorbell and the porch lights.

I like the idea of putting all wiring in conduit for ease of future changes. And if they specify metal conduit for switch drops, or BS 8436 cable it removes the need to have RCDs where they'd rather not.

Unless they want to go to the expense of RCBOs throughout, the CU should have at least 3 sections, 2 on RCDs and one not into which they can install a mix of RCBOs and MCBs.

If they live somewhere where supplies are dodgy in the winter, have the lights, the boiler supply, and a socket in each room wired to a separate CU, or a separate section in a large one, that can be supplied by an emergency generator - lights, heating, TV and a kettle/microwave make life a lot more bearable.

Flood-wiring with Cat6 or Cat6a cable is worth thinking about.

 

[electronicsuk]

And even then what about all of the sockets?

You'd have to have RCDs at the point of utilisation, and quite frankly, not only would RCD sockets be ridiculously expensive, they would also look pretty horrendous all over a house.

 

[paulp51d]

A very good point about this being a good time to bite the bullet and get all the work done. I think based on what has been said it's time to get somebody to look at it.

Cheers all.