House wiring age

goodValue

A recent survey stated that the lifetime of wiring is only 25 years.

Whereas a recent post suggested that 40 year old wiring would normally be ok.

Are the any Building Industry Standards that say what the life expectancy of wiring should be?

Slithery

It all depends on the wiring material.

Some will only last 15, some will last 50+.

NameUnavailable

I don't think many places are rewired after 25 years.

macman

It's not just the wiring: a house last rewired in 1980 will have an inadequate no. of sockets, no RCD protection on the CU, possibly no earthing on the lighting circuits. The wiring itself might still be satisfactory though.

tacpot12

PVC-covered electrical cable have a life well in excess of 25 years, and there is a perfectly adequate method for assessing whether the PVC is breaking down - insulation resistance testing which is part of a standard Electrical Installation Condition Report (EICR). You need an electrician qualified in testing to perform an EICR. Ideally, you would have one done every 10 years and can see if the insulation resistance of any circuit is falling over the years. Once they start deteriorating badly, that's the time to consider the timing for a re-wiring job - the electrician will know the acceptable levels. There are no industry standards for how long materials should last for, it is down to each manufacturer to set the warranty that they will honour, but the warranty on PVC-covered electrical cables is generally a warranty against manufacturing defects, not for a specific life-span. 

GDB2222

macman said:

It's not just the wiring: a house last rewired in 1980 will have an inadequate no. of sockets, no RCD protection on the CU, possibly no earthing on the lighting circuits. The wiring itself might still be satisfactory though.

A new consumer unit is an awful lot less expensive than a complete rewire.

If the existing CU is big enough, you may be able to fit RCBOs. These replace the individual circuit breakers and include an RCD. They are actually better than the usual arrangement that has several circuits protected by one RCD.

ProDave

I would be horrified if cable installed only 25 years ago was at the end of it's life.  That simply does not happen for internal PVC wiring within a house.  About the only case I can think where that might apply would be if someone has wrongly used PVC wiring surface mounted outside say for outside lighting where that would be in a poor state after 25 years.

I regularly see 50 or more year old wiring still like new.

FreeBear

Other things that can affect the life of cabling..

• Vermin chewing through the insulation.
• In contact with polystyrene (insulation) - The polystyrene leaches plastisers out of the insulation and it becomes brittle.
• UV light can degrade the insulation - Not normally an issue as most wiring is buried in walls/floors/ceilings.
• Bodger Joe doing a bunch of well dodgy DIY on the electrics.
  

pumas

Sold my 1965 built, house last year after I'd been there 35 years. Bits and pieces added over the years, but no re-wiring and original fuse box. Nothing failed in 55 years. 

GaleSF63

macman said:

It's not just the wiring: a house last rewired in 1980 will have an inadequate no. of sockets, no RCD protection on the CU, possibly no earthing on the lighting circuits. The wiring itself might still be satisfactory though.

ProDave said:

I regularly see 50 or more year old wiring still like new.

My mother's house was built in 1953 and not rewired until about 2010. Apparently the wiring was still in very good condition, but yes, the house needed an army of extra sockets and up to date consumer unit and other things I'm not knowledgeable enough to name. 

I expect, like most things, the need for updating varies with the quality and adequacy of the original installation. 

AdrianC

GaleSF63 said:

macman said:

It's not just the wiring: a house last rewired in 1980 will have an inadequate no. of sockets, no RCD protection on the CU, possibly no earthing on the lighting circuits. The wiring itself might still be satisfactory though.

ProDave said:

I regularly see 50 or more year old wiring still like new.

My mother's house was built in 1953 and not rewired until about 2010. Apparently the wiring was still in very good condition, but yes, the house needed an army of extra sockets and up to date consumer unit and other things I'm not knowledgeable enough to name. 

I expect, like most things, the need for updating varies with the quality and adequacy of the original installation. 

There's replacing the original componentry - and there's upgrading and extending it.

Consumer units? There's massive benefits in replacing an old bakelite rewirable-fuse CU with a modern split-load RCD/MCB one. There's little benefit in replacing a 20yo plastic one with a current-reg metal one.

Sockets and light fittings? There's cosmetic benefits in replacing old hardware with new. There's functional benefits in adding a lot more sockets to support modern living, removing the mass of trailing extension leads that you'd otherwise be saddled with.

Actual wiring? If it's still lead-clad or cotton-wrapped, replace it. If it's PVC black/red, your call for simplicity. If it's PVC brown/blue, little point.