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Yes, all of the lighting back boxes I opened had them. Have see them a couple of times before, similar aged propertiesInteresting I note that the metal back boxes have plastic threads on both sides?
Discuss 70s house, aluminium conductors in the UK Electrical Forum area at ElectriciansForums.net
Yes, all of the lighting back boxes I opened had them. Have see them a couple of times before, similar aged propertiesInteresting I note that the metal back boxes have plastic threads on both sides?
Yes i figured as much. In this example it could make for a nasty swap if someone were to fit a class 1 switch and not link the CPC currently terminated in the back box to new metal fitting. Interesting stuffVery common for installations with wiring or switch drops with no CPC. Insulates the plate screws from the back box.
Very common for installations with wiring or switch drops with no CPC. Insulates the plate screws from the back box.
View attachment 54887rank Mate it's not helpThe conductors should probably be coated with an anti-oxidant paste designed for aluminium electrical terminations. I use Ideal Noalox, though it's usually on much larger conductors.
View attachment 54888The conductors should probably be coated with an anti-oxidant paste designed for aluminium electrical terminations. I use Ideal Noalox, though it's usually on much larger conductors.
Diameter I should imagine, with a micrometre as the test instrumentAre you measuring the csa….or the diameter?
Yeah, that installation looks very odd, 1mm2 was not normal, nor would be the use of twin & earth on lighting circuits in that period, also running the neutral to the switch was old-style - a sign of the use of singles just prior to using twin cable.
I would guess that it was an old electrician following the 'old' ways with the new cable of the time!
Btw, since there is a new consumer unit (mcbs or cartridge fuses) then you can up the cable rating by 133% as it's no longer course protection, but I guess you would know that
Are you measuring the csa….or the diameter?
Diameter I should imagine, with a micrometre as the test instrument
Twin cable was in use for many years before PVC insulated cable came along, TRS or lead twin was widely used much earlier than that aluminium cable was installed.
In all the old books I have read or collected on electrical installation I think I've only seen neutrals at the switches as a relatively recent method.
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The diameter is being measured and the CSA calculated from that.
The diameter appears to be 0.210mm on the micrometer (if I'm reading it right) which gives a CSA of 1.03mmsq which is within a sensible tolerance of a 1.0mmsq nominal size.
Just to complicate matters, the hall and landing lights are 3 plate/ loop in at the rose (with obligatory borrowed neutral), and the bathroom is loop in at a junction box.
@Julie. , you also have a copy of the 14th ed of the regs, am.1976? I'd not heard of rewireables as being referred to as course protection before, until I saw it mentioned in the tables in it a couple of days ago. Also highly frustrating that table 24M is missing from it.
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