Rewiring - cost estimate

[Chris B]

Now I know before I ask this question that the answer is "it depends", but I am hoping that someone could give me at least a vague idea about numbers before we get someone in for a formal quote

A friend has inherited part of a standard 4 bedroom detached house with garage. It was built in the early 70's and the electrics have not been touched since (still has re-wirable fuses in the CU).

I suspect that it needs all the wires replacing (currently has electric cooker but no electric shower), all faceplates and switches replacing (for cosmetic if no other reasons), CU replacing and a few extra sockets adding.

Can anyone give me a rough estimate of likely cost (£100 - obviously not, £1000 - still no, £3000 - is this getting close, £5000 - surely not).

I rewired a complete house myself in the mid 80's but with all of the new regulations probably wouldn't want to do this again, especially as this is not my house, but is there any DIY prep work that I could usefully do which might reduce the cost. I could easily remove most if not all of the old ring wiring/fittings and replace with new, leaving it to be terminated at the new CU, but would this mean anyone replacing the CU would not sign up for it?

Thanks for any advice.

[Tim Watts]

Does conduit exist or is this going to involve chasing all the walls? If so, tell them to use conduit (20mm oval will take up to 2.5mm2 cables with little extra chasing).

[Dave Plowman (News)]

Unless things have been badly bodged, there's a good chance the wiring is still in perfectly serviceable condition.

[Chris B]

Don't know the answer to that one - havn't really inspected it in that much detail yet.

[GB]

How long does the PVC insulation last?

[Robin]

And I expect they are naturally cautious. (I was up close and person last year to 2.5mm T&E installed under floors over 30 years ago. After wiping off the dust if look and felt like new.)

[Dave Plowman (News)]

I re-wired this house in the '70s, and there's no sign of deterioration anywhere. A couple of years ago, I did a pretty major refurkle of one room which involved quite a bit of electrics, and the original wiring was still fine. If the PVC had suffered, I'd assume it would go brittle.

Might be different on any wiring exposed to the sun, etc.

[Harry Bloomfield]

GB explained on 15/02/2017 :

Usually forever, providing it was properly installed, not overloaded, or otherwise damaged, there are no botches and it has proper earth wires included.

I would guess at £2000 to £5000, but much depends on what extras might be needed beyond the basics. Best to get network cable installed at the same time if they might be needed, plus TV/satellite cables too.

Worth deciding exactly what you want, then getting three quotes and making sure they have Part P qualification, can prove it and can provide references too.

[The Natural Philosopher]

I have seen PVC exposed to sunlight be rubbish in less than 5 years. Conversely I've seen 70's PVC cable still in perfect nick.

[spuorgelgoog]

and better than the crap sold nowadays.

Even comes in proper colours too :-)

Owain

[spuorgelgoog]

It probably needs a lot of extra sockets adding, and it may be useful to sp lit existing lighting circuits halfway and put a new cable from the split b ack to the CU, to spread the lighting across more circuits, but it probably does not need all the wires replacing unless there is actually something w rong with them.

I split my lighting circuit in half and used the new leg to put in smoke de tectors and wall lights, and put in a new socket radial (which if it gets a ny longer will find itself back at the CU and can become a 2nd ring).

Owain

[Dave Plowman (News)]

If DIYing, most would probably make use of existing wiring if good where possible.

But in terms of cost when getting the whole job done by a pro, it might be easier to simply rip the lot out and start afresh. No dispute then if anything needs fixing afterwards.

[Brian Gaff]

To be honest our house was done in the 70s, and looking at some of thewiring, pvc covered in most places it still looks good, so unless there is some strange fault or other mitigating circumstance, could one just not do the Cu and fixtures and fittings on the old wiring after a cursory inspection for gotchas? If I look at ours we replaced the fuses with breakers, but nowadays a more techy type of protection should be used no doubt but apart from that.... Brian

[Tim Lamb]

Hmm.. I have lots of red and black 1.5 and 2.5 tw+e in a tasteful white pvc:-) Once used but carefully gathered.

[ARW]

Agreed.

The biggest problems (at a guess) is that there are probably only two single sockets per bedroom (just where you don't want them) and possibly only one socket circuit for the whole house. The main bonding will be in

4mm or non existent and you can bet they borrowed a neutral for the landing light strapper.

[Nick]

As lights are now lower power, approximately 20% the level, when the house was originally designed. Why would the light circuit need to be split in two.

[Harry Bloomfield]

Brian Gaff expressed precisely :

Ours was done around 1983, since when I found it necessary to add numerous extra sockets and a few lights, a higher power shower. Were I wanting what I have now installed, I would likely be thinking of a bottom up refurb.

[Harry Bloomfield]

Nick laid this down on his screen :

For safety, you would then still have a working lighting circuit, if one developed a fault.

[Andrew]

So what ?. I still have those in a 1976 built house.

Why ?. It will have modern PVC wiring, so why would you replace it ?. The lighting circuits might only be 1mm2 but so what, these days we only have low energy bulbs.

The ring mains will have a 1mm2 earth wire (went up to 1.5mm in ?1984) so simply adding some RCD's to the power circuits would suffice if you are worried. Even my 3 bed semi had two lighting circuits, one up and one down, but with some odd arrangement for the 2-way switching on the stairs (bottom switch allowed landing light to be tuened off, but landing switch did not affect hall light).

Only if you intend renting it out would a CU replacement be deemed 'necessary'.

[GB]

Useful for all sorts of things. Holding bundles of wood together, for example.