Trying to understand my wiring.

[MarkFish]

I've just bought a 3 bed semi build in 1960.

All walls are brick.

The original sockets, of which there are few, have pre-pvc cables. (Rubber? Cotton?) I've had a look at one or two and there's no evidence any of them are part of a ring main. The cable reaches the sockets through conduit built into the walls originally.

There are a larger number of surface mounted sockets which look pretty old to me, but I suspect have been retro fitted at a later date but together, at the same time. These have PVC wiring. Again there's no evidence these are part of a ring main. The wires to these appear to come through a hole drilling in the wall. I assume that the cavity has been used to route the cables but that could be wrong.

I can't see what's going on the (rather elderly) consumer unit end and really don't want to touch it. Having said that, it's pretty clear there isn't a wire from every single plug back to the Socket fuse.

Clearly nobody can know how my wiring is set up without looking at it, but I wonder if people might have some general insights into how wiring might typically have been routed/wired up between the 60s and the 80s.

Specifically:

1) How long should the pre-pvc cable rubber/cotton cable last before it must be replaced?

2) The lack of any evidence of a ring main raises the rather scary prospect that all of the retro-fitted sockets (and perhaps all of the original sockets) and getting their power from one thin wire going back to the consumer unti which must get rather hot. Is what I'm describing sounding typical for a house of this age? - By which I mean did they use a minimal ring main and then run a load of sockets off as spurs?

3) Was routing cable through wall cavities typical?

I don't actually have to touch the wiring in the house - is leaving sleep dogs to lie a bad idea? (These dogs appear to have slumbered for 30 years plus already.)

What's the situation with building insurance? Will it cover me for historic bodges?

I fully understand that nobody can tell me specifics about my wiring without looking and that if I want to touch the wiring I have to get a pro to do it. I just want to understand what's could be going on.

 

[ricicle]

If you are considering any building work and/or redecorating now is the time to consider a rewire. Any wiring that predates PVC is in desperate need of replacement so you might as well face facts.
It sounds like a condition report would be a waste of time from your description as the outcome would be rewire anyway.

 

[jj4091]

I think what you are trying to say is does your house need re-wiring or not? Really you have answered your own question in saying we don't have crystal balls ( not personally anyway ), but I would say that the life of the vir cables you describe has past it's sell by date & in looking inside the sockets you may have already disturbed dodgy insulation & introduced potential hazards. Call a spark in for a definative answer, in fact call several in for estimates.

 

[PrenticeBoyofDerry]

Are you sure these cables are still in use and have not just been left after the circuits have been rewired?
If they are still part of the installation

1) How long should the pre-pvc cable rubber/cotton cable last before it must be replaced?

It's time to go, it will likely fail and insulation resistance test

2) The lack of any evidence of a ring main raises the rather scary prospect that all of the retro-fitted sockets (and perhaps all of the original sockets) and getting their power from one thin wire going back to the consumer unti which must get rather hot. Is what I'm describing sounding typical for a house of this age? - By which I mean did they use a minimal ring main and then run a load of sockets off as spurs?

If not all or some of the cables in the circuits are rubber/cotton as you described above, sounds typical of alteration and addition that have been done, which could well be dangerous.

3) Was routing cable through wall cavities typical?

Yes but not suitable

I don't actually have to touch the wiring in the house - is leaving sleep dogs to lie a bad idea? (These dogs appear to have slumbered for 30 years plus already.)

It's a matter how long does a sleeping dog lie before it wakes and bites you where it hurts?

What's the situation with building insurance? Will it cover me for historic bodges?

did you not get a report on the installation when you purchased the house and how was the house described when sold?

I fully understand that nobody can tell me specifics about my wiring without looking and that if I want to touch the wiring I have to get a pro to do it. I just want to understand what's could be going on.

Appreciated and you are wise in doing so.

I would say that you should be looking at upgrading your installation. It sounds like your cables are very dated and by your description could well be declared dangerous. What you must consider is the safety aspect and not just about things working, how long they will work for or whether insurance will cover you if anything should go wrong. You must consider the worst case scenario if a hazard does occur.
I would suggest you employ an electrician and have at least a report done on the installation and expect the worst.

 

[riveralt]

Without seeing your installation in situ it is impossible to tell but where there are rubber cables you are looking at rewire terroritary.
Given the house age I woulde also suspect that there is no earth to the lighting circuits - wasn't required then but is now - and I would suspect that there will be no RCD's present.
You probably will not have main protective bonding in place and the main earth cable, if it exists, will probably be too small.
A rewire would probably cost around £2000 or more depending where you live.
I'd hope, but seriously doubt from your comments, that you had some form of electrical survey done before you bought the house. If you had you could have negotiated a discount of at least £3000 of the list price.

 

[chivers67]

Sounds like some of your circuits are radials as opposed to ring finals, but difficult to say

Have to echo what others have already stated Rewire before you decorate the house to your own taste....

 

[JohnW2]

I agree with everything that has been said, and have nothing useful to add. The one thing which slightly surprised me is that a new build in 1960 was not wired in PVC cable. When did PVC become the norm (I thought it was mid/late 50s, but clearly must be wrong)?

Kind Regards, John.

 

[flameport]

How long should the pre-pvc cable rubber/cotton cable last before it must be replaced?

It should have already been replaced 20+ years ago.
When manufactured, it was expected to have a 25-30 year lifespan. Therefore it's already two decades beyond that.

Rings were common then, but as various questionable modifications have been made, there is no way to know what kind of mess you have now.

Cables were pulled through cavities, but this is no longer allowed for several reasons - cavity wall insulation, damage to cables where you can't see them, cables making a track for water to cross the cavity.

What's the situation with building insurance? Will it cover me for historic bodges?

Maybe, but there will be a section in the policy which requires the property is maintained in a proper state and this would include replacing items which are life expired.
Therefore if your house sets on fire because the wiring is ancient and should have been replaced long ago, it is likely you will not be covered.

If the wiring is singles in round steel conduits, there is a reasonable possibility of new wires being pulled in which would avoid damage and destruction to the walls.
However that is only likely to be of use for the lights, as the number of sockets in a 1960s house was very small and totally inadequate for a property today.

 

[MarkFish]

Thanks everyone for comments so far.

If the consumer unit is replaced with something more modern with an RCD will everything 'downstream' of that need to meet current regs? (especially with regard to routing.)

Secondly, I'll be wanting a new ring circuit to serve the kitchen alone. Is it against regs to use the kitchen ring main to add one double socket in the lounge?

I'll have a look under some boards at the weekend before the guy comes to give the first quote on Monday but in the meantime: The plug sockets I've investigated have only one cable going to them, hence I'm concerned that there's no ring main or that they're in some horendous daisy chain with a ton of load ultimately going through one 2.5mm wire. Now the panic has subsided a bit, it occurs to me that a more likely explanation for the apparant lack of a ring circuit is that there's a ring circuit under the floorboards upstairs which I haven't clapped eyes on yet and they've run all the downstairs sockets off that on spurs (one spur per socket), presumably to save them the return cable IYSWIM. If so, personally, I have no problem with leaving that (if it were legal for the electrician to do that whilst making changes elsewhere in the same circuit.) Was it typical for people in the 60's on new builds to run every individual socket on spurs off a ring main? If it was it would make my wiring make sense.

Why the hell isn't it standard practice for every house to have a decent wiring diagram. In fact, decent plans of everything. Even if it became out of date it would make life so much easier.

 

[MarkFish]

If the wiring is singles in round steel conduits

Could you exaplin "singles"?

Yeah, the original wiring is in conduit and would probably pull through.

However 60pc of the sockets have been added later. Although the PVD cabling looks sound the routing appears to be via the cavities and therefore wouldn't meet regs.

I think the major electrical work has been carried out in the four phases:

- Original.
- Addition of a large number of surface mount sockets probably routed throught the cavities. Assuming they are individial spurs off a ring main I'd be happy with keeping that if there were a legal way to do so.
- New lighting wiring. (Still no earth) Again if it were legal to do so with a new consumer unit I'd be ahppy to keep this.
- Very modern looking abortion wiring. Terrifying and none salvageable IMHO. Spurs on spurs on spurs. Spurs with no fuse. I fear as the guy progressed deeper into old age he didn't really keep an eye on the people doing work for him.

 

[Adam_151]

There are various strange implementations of ring circuits which happened in the 60's.

Ring round a chain of joint boxes and a 2.5 (well actually a 7/.029) off each joint box to a socket.

Ring round the upstairs, dropping spurs downstairs, often each spur having two sockets as a previous edition allowed two singles or one double per spur.

Two 7/.029 cables from the fuse to a big joint box (or a few of them in one location) and all sockets in the house (not many, radiating from there)

And other variations of the same

As to whether the board can be changed without bring the circuits connected upto standard. That is totally dependant on the exact none complinace. Unearthed lighting circuits can be reconnected providing all fittings are class 2 and a label is applied. A lashed up circuit with broken earths all over the place would need repair though. And you wouldn't want the electrician to re-connect a cirucit with low insualtion resistance to a new RCD protected board, nuisense tripping sometimes happens on circuits in good condition, bad condition ones would be a nightmare....

 

[riveralt]

Thanks everyone for comments so far.

If the consumer unit is replaced with something more modern with an RCD will everything 'downstream' of that need to meet current regs? (especially with regard to routing.)

The answer to this question is techincally yes. There is nothing in the regulations that stipulate everything must be brought up to current standards.
However, for your own safety, I would suggest that an Electrical Installation Test report be conducted on your premises before anyone fits an new Consumer Unit. This will highlight problem areas and give you a better chance of judging what needs to be replaced and what doesn't.

As a mininum the old rubber insulated cables will need to go, the main protective bonding will need to be brought up to current standard and the lighting circuits will have to be properly earthed.

Secondly, I'll be wanting a new ring circuit to serve the kitchen alone. Is it against regs to use the kitchen ring main to add one double socket in the lounge?

No it is not against the regulations I have done that numerous times where a socket is need in a room and it is easier to drill through from the kitchen rather than damaging a whole wall - the electrician should in any case provide you with a schedule and/or diagram of which sockets are on which circuit and a copy of that should be next to your consumer unit.

I'll have a look under some boards at the weekend before the guy comes to give the first quote on Monday but in the meantime: The plug sockets I've investigated have only one cable going to them, hence I'm concerned that there's no ring main or that they're in some horendous daisy chain with a ton of load ultimately going through one 2.5mm wire. Now the panic has subsided a bit, it occurs to me that a more likely explanation for the apparant lack of a ring circuit is that there's a ring circuit under the floorboards upstairs which I haven't clapped eyes on yet and they've run all the downstairs sockets off that on spurs (one spur per socket), presumably to save them the return cable IYSWIM. If so, personally, I have no problem with leaving that (if it were legal for the electrician to do that whilst making changes elsewhere in the same circuit.) Was it typical for people in the 60's on new builds to run every individual socket on spurs off a ring main? If it was it would make my wiring make sense.

This is why a Electrical Installation Inspection Report is so important......

Why the hell isn't it standard practice for every house to have a decent wiring diagram. In fact, decent plans of everything. Even if it became out of date it would make life so much easier.

It is required now - though not many seem to do it- not sure when it became such a requirement though.

 

[MarkFish]

There are various strange implementations of ring circuits which happened in the 60's.
Ring round a chain of joint boxes and a 2.5 (well actually a 7/.029) off each joint box to a socket.
Ring round the upstairs, dropping spurs downstairs, often each spur having two sockets as a previous edition allowed two singles or one double per spur.
Two 7/.029 cables from the fuse to a big joint box (or a few of them in one location) and all sockets in the house (not many, radiating from there)

Many thanks Adam, that's exactly the kind of information I was looking for. Any of those could be a candidate and fit with what little wiring I've seen under the floorboards.

As to whether the board can be changed without bring the circuits connected upto standard. That is totally dependant on the exact none complinace. Unearthed lighting circuits can be reconnected providing all fittings are class 2 and a label is applied. A lashed up circuit with broken earths all over the place would need repair though. And you wouldn't want the electrician to re-connect a cirucit with low insualtion resistance to a new RCD protected board, nuisense tripping sometimes happens on circuits in good condition, bad condition ones would be a nightmare....

Mucho gracias, all noted.

 

[Adam_151]

I agree with everything that has been said, and have nothing useful to add. The one thing which slightly surprised me is that a new build in 1960 was not wired in PVC cable. When did PVC become the norm (I thought it was mid/late 50s, but clearly must be wrong)?

Kind Regards, John.

There was a cross-over period, some manufacturers produced the new pvc cable, which I expect some electricians refused to use, prefering to stick with the rubber that they'd always used. PVC was in its early days and not every manufacturer had mastered getting the sheath to separate easily from the cores, and variations such as VIR insulated conductors within a PVC sheath, Polythene insulated and sheathed were around, Even when they'd worked out how to stop pvc sticking to itself, the earlier versions would later prove to have an issue with the plasticiser de-grading and dripping out into accessories and terminals, by the end of the 1970's most PVC was reasonably stable, although it would be the 80's before the 2.5mm ended up with an adequatly sized CPC.

 

[ricicle]

How come everyone got a 'thanks' except me