Electricians - am I being mugged?

[DS3R]

1960's concrete block flat, all original (and classy with it!)

Fuse boards need changing (even I know that!), most of the face plates (sockets & switches) have been changed, but some originals need replacing.

The wires are in tubes in the concrete, and setting aside that some may have collapsed, the builder says he would insist on a full re-wire irrespective that cable from the 60's is 10 times thicker than today's nonsense.

I accept regs have changed, but am not totally convinced it all needs changing. I would have thought even sparkies are allowed some discretion and common sense to say if the level of conductivity in a wire continues to be acceptable for the purpose required, then does it really need to be pulled out (or worse of course, chiselled)?

We are refurbing the whole property and I'm not going to lose any sleep if it has to be done, I just want to be sure it's being done because (setting aside the false economy of having to do it later of course), and not just because the boss of the building firm is an electrician by trade.

In the grand sceme of the overall price the amount budgeted for it is not huge, but having had fuse boards changed and wires checked by a spark on a 60's house and that was good enough for a certificate for sale, I'm struggling to see how this can be so different.

[dave_s13]

Not sure on the technicalities but it's not about the size of the copper cores, it's the insulation that perishes over time.

I wouldn't want to buy a house that had 40-50yr old wiring.

[crispian22]

Unfortunately wiring doesn't last forever,after 50 odd year's the insulation will have started to degrade and if its all buried in metal conduit in the concrete it won't readily be open to a full inspection throughout the whole installation.it may well test up ok but if there is an unseen section with exposed live conductors then this as you will understand is a potential risk to persons or property.

[z4chris99]

dave_s13 said:

Not sure on the technicalities but it's not about the size of the copper cores, it's the insulation that perishes over time.

I wouldn't want to buy a house that had 40-50yr old wiring.

Alot of new regs mean sparkles are not allowed to just change the odd bit here and there.. If the wiring is old it may not be legal to just change the fuse board

[DS3R]

As I said, I appreciate the false economy of not doing it now anyway, but if it is as straightforward as it literally can't be signed off as is, then that's my answer. I just can't find what says that where!

[simion_levi]

I understand that there are two schools of thought - one says PVC insulated wiring lasts near enough forever (some commentators note specification is over 20 years at full load) and as long as all circuits test OK, have CPCs without any green gunk at connections, appropriate bonding to services and have not been used over their rating (10KW shower installed on existing 6mm cable etc) then no need for wholesale replacement. The other says replace the lot based on age, without even looking at it.

I prefer the first myself, though I am not an electrician.

[northwest monkey]

simion_levi said:

green gunk at connections

O/T but what is the green gunk?

Seen it a few times but always forgot to ask my electrician what it is!

[DrDeAtH]

The 'green gunk' as you put it, is actually the plasticiser leaching out of the insulation, it is NOT verdigris - that is copper corrosion.

Google it and you will see...

Best practice is now to rewire, as even if the insulation resistance is good at the moment, it will quickly begin to fall as the cable degrades and the insulation starts to become brittle.

[hairyben]

If it's original 60's, there probably isn't any earth conductors, as they just used the steel conduit. Unfortunately the joints rust and thus earth continuity can't be guaranteed.

If a client really insisted they didn't want rewiring done, and the installant tests okay, the box could be changed but, depending on test results, you'd be looking at a 1-2 year re-test advisory and negative comments on the test cert instead of 10 year as the spark can't guarantee the condition of conduits within the fabric of the building. Also you can't spur extra sockets/points off the conduit using twin&earth, bad practice, and I'm guessing in a flat redevelopment you'd want some extra bits. Given with conduit installations it's normally fairly straightforward to rewire with earth conductors this is the sensible option.

[DS3R]

Sounds like it makes sufficient sense then, I was just a bit put out that he didn't look at anything before declaring "it needs a rewire" (we weren't even in the property!), so he had no idea if anything had been done, it was just taken as a given and priced accordingly!

Thanks for your input guys, v much appreciate it.