Two electricians telling me different things, confused and a bit concerned

[ebee]

FWIW if it was built in 1977, and has white twin and Earth on the sockets it’s almost certainly 2.5 mm / 1.0 mm

I disagree

 

[securespark]

AFAIR, white twin and earth (not LS0H) started appearing in sheds in the 80s.

But certainly, I would expect late 70s-installed cable to be metric.

 

[ebee]

If it`s rubber then it would not automatically be bad, you could actually find it all tests OK and is in good condition, not impossible but is starting to become more unlikely. I would err on replacing it in reality though.

Old colours do not matter, it`s only us humans that (sometimes) follow colour codes. Electrons don`t give a damn about insulation colours.

Unless you definitely certainly know it is TNS and is very unlikely to change in the near future I would bond as if TNC-S even if it presents as TNS at the moment. It could be quite TNC-S like! it only needs a joint or two between you and the transformer to make it very TNC-S ish in behaviour.

If the twit next door has linked E & N together then would it not affect yours?

 

[ebee]

Sometimes when you know or suspect it needs a rewire and the customer wants "a few sockets and lights moving" then a rewire becomes a more prudent course to consider anyway.

Ref consumer unit - I would RCD (Preferring RCBOs) and I would SPD, I would be averse to AFDDs.

 

[Murdochcat]

I disagree

Our house is about that vintage and was 2.5 / 1.0 before being refurbished

 

[TONY1966]

Sorry John I do not agree "anybody saying a rewire is required without doing any testing needs be shown the door".

First of all, the most important piece of equipment to use - the Mark One Eyeball. Sometimes can indicate it needs a rewire, sometimes indicates it might not need a rewire (although might indicate a few fixes or sometimes indicates it looks ok so far). That equipment is the first thing, a look around at what is.

Then, again the Mark One Eyeball and this time we will open a few things up to have a better look (sockets, switches consumer unit). Again we might think one of the three options above might apply.

Either of these might lead us to confirm or suspect it might well need a rewire.

If we need further info then testing occurs.

I do not do much in the way of PIRs/EICRs but on occasions I have there are a few I have cut short and reduced my fee accordingly because I have concluded a rewire required in full or in part, without any testing.

I definitely wont assume the first guy was a scammer, i will get a condition report done. It was the remark about wire insulation lasting 25-40 years that made me question it a bit since i dont think people have rewires every 20 years. That and the fact he had condemned my entire house wiring by looking in the garage and i couldnt see any damaged wires

My colleague who gave such different advice is qualified but wasn't after work as he is fully employed... he wasn't particularly thorough as it was just a quick look as a favour, he looked in the garage, popped into the loft and took 2 sockets off the wall (one upstairs one downstairs) and said what he had looked at seemed fine, aside from the bonding.

 

[EFLImpudence]

aside from the bonding.

That will only be because the rules about size have changed - nothing to do with its condition.

 

[Adam_151]

It was the remark about wire insulation lasting 25-40 years that made me question it a bit since i dont think people have rewires every 20 years.

This is one of those things that has historic basis, but doesn't really hold true anymore. The old vulcanised rubber insulation was said to have a design life of 25 years, although some of it would last longer. That stopped being put in about the early 1960s so any still left is is probably approaching pensionable age these days....

When we moved on to PVC, generally it has a much longer lifespan, and generally 80+ years shouldnt be an issue if not overloaded, or suffering environmental damage, although none of it is yet that old. There were some issues with early PVC with plasticiser migration (generally shows itself at accessories where the cable drops down from above), up until the early 80s the CPC was undersized (a problem with the rewireable fuses fitted at the time, but unless fault current is really high then no longer a problem when on type B cirucit breakers)

The main things that could lead to a rewire on an installation from the 70s are if its been bodged about with too much by DIYers or kitchen fitters over the years (easier sometimes to start again if there is too much bodgery) or if you are wanting a load of extra points in all the rooms and its easier to just start fresh rather than to add on all over the place, although this might be limited to some areas (i.e. complete kitchen refurb might be done as new power cirucits for just that area, and joint the existing ring through)

 

[securespark]

Our house is about that vintage and was 2.5 / 1.0 before being refurbished

I'm not sure when the 2.5 CPC was upgraded to 1.5. I think it was the mid 80s. That came about because of an issue with protection by BS 3036 fuses.

It can be solved by switching them to MCBs.

 

[securespark]

The main things that could lead to a rewire on an installation from the 70s are if its been bodged about with too much by DIYers or kitchen fitters over the years (easier sometimes to start again if there is too much bodgery) or if you are wanting a load of extra points in all the rooms and its easier to just start fresh rather than to add on all over the place, although this might be limited to some areas (i.e. complete kitchen refurb might be done as new power cirucits for just that area, and joint the existing ring through)

The other is green goo.

 

[Harry Bloomfield]

said what he had looked at seemed fine, aside from the bonding.

and that doesn't have to be upgraded, retrospectively - though advisable.

 

[JohnW2]

Sorry John I do not agree "anybody saying a rewire is required without doing any testing needs be shown the door".

I was perhaps not clear enough. I was not agreeing with the comment as a generalisation but, rather, in the context of a house built in 1977 and wired with PVC cable. I also 'assumed' (I know!) that 'testing' would also include at least a cursory visual inspection (with the 'Mark One Eyeball'), whereas we are told that "...

..... he literally looked at the fuse box and told me 'rewire needed'

Do you really believe that an 'electrician' should not be 'shown the door' if he/she declared that a complete re-wiree is needed, of a 1977 house with PVC wiring, purely on the basis of just looking at the 'fuse box' ?

Kind Regards, John

 

[Murdochcat]

and that doesn't have to be upgraded, retrospectively - though advisable.

Not sure I agree with that. Any spark changing circuits or adding them would need to confirm earthing and bonding are up to spec

 

[SUNRAY]

AFAIR, white twin and earth (not LS0H) started appearing in sheds in the 80s.

But certainly, I would expect late 70s-installed cable to be metric.

Silver Jubilee year 1977 we added a temporary feed for an event which was white 2.5mm² and after we recoiled it on a bigger drum, the same thing happened for golden Jubilee with the same length of cable and it was finally 'used up' for some 13A theatre dimmer lighting circuits 2007.

 

[SUNRAY]

Not sure I agree with that. Any spark changing circuits or adding them would need to confirm earthing and bonding are up to spec

Possibly but depends on the works being done.