Re: single & earth??? wiring help needed!

[Kevin Hawkins <lists@xxxxxxxxxxxxxxxxx>]

JT @ Home wrote:
> Morning!
>
>
>
> I was asked to install a second light and switch into a friends
property
> yesterday, so I went over and installed the fitting & the switch,
leaving
> just the final connection to be made. So after much insulation
shifting in
> the loft, I found what I understand to be the lighting circuit.
However! It
> only seems to be a single live and earth in one casing.
>
>
>

(Disclaimer - I'm not an electrician !!!!)

Just a comment...  do be careful as you are probably treading dangerously
re the new the regs - even more so if putting in someone elses' property, I
expect there may be lots of liability issues here.  Is it possible this
single wire you found is destined for a switch ? ie a switched live or live
feed to same. ?


> So I need to find the neutral connection to it, would this be located
at the
> light fitting? Iirc there are 3x single and earth connectors at each
ceiling
> pendant.
>
>
All the down pendants must have a switched live, neutral and now under
latest regs an earth connection. Most will also have a permanent live
connection.    . Live and switched live go to switches - plus an earth
of course, neutrals are not usually taken to switches.  I have seen the
lives looped around switches acting as the only supply to the lighting
circuit with only switched live present at pendants, maybe you have this
arrangement.

You need to be very careful to source the live and neutral from the same
feed from the distribution box, thus the current in the neutral and live
wire are exactly equal as one carries the return of the other. In any
one twin feed cable the live and neutral  currents will then be equal
and opposite. This is easiest to achieve I would think from a single
pendant source if live is present - yours sound like they might have
this.  Several reasons for this but if you do have any earth leakage
breaker trips in your supply having unbalanced loads upsets them
(causing them to trip) as they decide the current inbalance indicates a
leakage fault..  Also you can get strange  situations where despite/when
pulling fuses and detaching neutral wires or even isolating the neutral
neutral via the main switch the neutrals can then become live because
their 'live' is fed from a different circuit/dist box and comes back
through the loads to the now floating neutral of a different circuit If
that makes sense) .  I'm sure there's lots of other issues too but
running everything as a T off an existing pendant if possible is
probably the most logical and compliant way (if you have live there) as
if those are wired correctly yours will be too. If you don't have live
there then identify a pendant and the switch that controls it and use
that live (on the switch) and the neutral from the matching light
pendant - you need an earth too of course.    (Poss other suggestion -
may not be easy to do though - run a new twin and earth from the fusebox
??)


I'm sure Ben or someone will chip in with an official (regs compliant) view

K
> I'm stuck as to where I can find the appropriate neutral for this new
light
> fitting, could anyone offer any suggestions as to where would be a
safe bet
> to find it? I just done want to start chopping into cables to find
that I've
> got the wrong one!
>
>
>
> Kind regards,
>
> Jonathan
>
>
>
>