"mark al" wrote
| a query for the electrically minded folk.
| i have discovered some of this type of wiring in the lighting
| circuits for my house.the socket circuits are rewired with new
| cable but the previous owner decided not to bother with removing
| it for the lights . obviously it will have to be removed but im
| just interested to know how old this cable would be and how
| urgently should i get it replaced ( all electrics functioning
| ok but safety wise who knows?)
It may well be in surprisingly good condition if it was properly installed
in the first place and not buggered about with since.
However, as the previous owner's rewiring job was rather incomplete it is
possible that the lead sheathed wiring was removed from the old fusebox and
connected to the new consumer unit without due regard to its earthing, as
lead cable is usually earthed by having a termination screwed onto the
sheath and then fixed into a conduit box. Also, at all the junction boxes
and ceiling roses the lead sheaths had to be bonded together. If this wasn't
done properly your lighting circuits and all the cable are unearthed, which
could be rather nasty.
What you can do (or get done) is a megger test for insulation between the
cores and the sheath, and for conductivity between all the switches and
points back to earth. If it passes those tests reasonably well then you
probably don't need to rewire before christmas, but the job should be done
soonish. If it fails those tests then the cabling should be regarded as an
immediate risk and taken out of service asap.