OLD OLD lighting circuit

[pcboffinuk]

Hi all,

My father has a fairly old house and I'm looking at rewiring the lighting for him, either as one of the jobs for my Part P 'competent person' assessment, or once I have that 'worthwhile' piece of paper.

The wiring is pre 50s, with individual cores all in black and badly deteriorating, running through metal conduit.

I haven't looked too closely yet, but it clearly all needs replacing,

The CU end runs from a fuse box with double pole fuses, which should give you some idea of how old the system is! (the neutral fuses were replaced some time ago with higher values to ensure that the phase ones are the ones that blow)

Does anyone have experience of replacing wiring in this sort of setup? What I am mainly wondering is whether the conduit is likely to be continuous, in which case it may be relatively easy to pull new wiring through it, or if it will just be lengths and it will catch at every change of direction...

From what I have seen on a quick inspection the wire/conduit exits the fuse box then goes down and under the floor - presumably it then comes up in the wall somewhere en route to the light fittings. (There are individual circuits for up and downstairs).

Apart from running for the hills, any advice on working on something this old is welcome.

One thing I certainly don't plan to do is test the existing wiring - I'm sure 500V up it would not do it much good!

Many Thanks

Gavin

 

[Spark123]

Be careful, there may be asbestos in them fuse holders. With any luck the conduit will be continuous so you can pull conduit singles into it, personally I'd run an earth to each point and tap an M4 machine screw in. I take it the wire is VIR? (iirc Vulcanised Indian Rubber?). You may be surprised how good a condition some of it is in, I pulled some out not so long back and it had gone at the ends and a short length into the conduit, the rest was in pretty good condition. Before you pull the old wires out, tie a draw wire or the new cable onto it. You can use some of the conduit grease to help the cables on their way too.

 

[breezer]

tie a draw wire or the new cable onto it. .

why not use the old wire as a draw wire?

although if conduit is rusty at joints etc = no earth continuity, i would not do it, rip the lot out to be safe

 

[the_jinj]

Done a few houses from times of yore where it was all conduit - rewire is 100X easier Them old school knew how to wore a house I tells ya

 

[pcboffinuk]

With any luck the conduit will be continuous so you can pull conduit singles into it, personally I'd run an earth to each point and tap an M4 machine screw in.

Spark, I do hope it is continuous as it will make pulling a lot easier.

However, I was planning to pull standard 1.5mm2 T&E through and provide an earth that way. Is there any reason why that would be a bad thing compared to using conduit singles? If I did use T&E. How important is it to ensure that the conduit is still well earthed? i.e. If a check shows that it is badly earthed would it need to be taken out or corrected to adhere to regs, assuming its left there purely as a route for T&E cable?

Thanks for the reply,

Gavin

 

[Spark123]

tie a draw wire or the new cable onto it. .

why not use the old wire as a draw wire?

Yup, I though I said that too

 

[Spark123]

With any luck the conduit will be continuous so you can pull conduit singles into it, personally I'd run an earth to each point and tap an M4 machine screw in.

Spark, I do hope it is continuous as it will make pulling a lot easier.

However, I was planning to pull standard 1.5mm2 T&E through.....

Conduit singles are stranded which helps them to be pulled into the conduit, flat twin and earth is (normally) single strand and imo will be a pain with conduit, especially where there are bends. I wouldn't consider using this type of cable myself.

 

[dingbat]

I agree with the last post. You simply won't be able to pull T & E through that stuff. Another point to consider is whether the points served are in the right places. Lights tended to be very close to the windows, so you may want to move them.

Usually easier to forget about the old conduit, although the switch drops may be useable... provided the switches are actually still where you want them and not behind re-hung doors.

 

[breezer]

Usually easier to forget about the old conduit, although the switch drops may be useable... provided the switches are actually still where you want them and not behind re-hung doors.

but to use the switch drops wpuld mean gaining access to the conduit, sawinging it off, trying to thread it (which will be very hard considering it will not be 20mm dia) to put a female bush or socket and bush to stop the cables bing chaffed.

hence my first post on this, dont use it, just rip it out

another thing, although i am assuming here, if its in the wall it may not be in a good condition

Oh and spark 123, yes, yes you did (sorry it was late and i only saw the first bit)

 

[bondy]

why were the light fittings fitted near windows. the house im in now has this with granny switches hanging above my head.

 

[breezer]

why were the light fittings fitted near windows. the house im in now has this with granny switches hanging above my head.

simple.

people could not afford curtains (seriously) so the light was put near the window to stop shadows being cast on them and to make it harder to see inpast the light from outside

 

[Steve]

breezer, i was told that the lights were hung near the window to mimic the natural daylight. Maybe this is why they were "hung" in pendant drops too, to simulate window-level light?

Anyway, any chance of a picture of that olde-worlde fuse box?

 

[JohnD]

I've found the old conduit switch drops are the only bits worth re-using. If you're doing the lighting in an entire house it save a lot of chasing, dust and grit, and redecoration.

All the rest of the lighting is easier without the conduit.

You need some kind of gland, nut or end" to protect the conduit edges (which in cheap household insrallations is likely to be pressed steel with a seam, thin and sharp) from cutting into the cable, especially in the loft where it is more likely to be disturbed or stood on.