Hello,
It appears that my whole lighting circuit has no earth. We are family
of four with young children, but it's me who usually handles the
lights ;-) Is this a clearcut case for a rewire or is there an easier
way remedy or avoid the problem.
Fred

It appears that my whole lighting circuit has no earth. We are family
of four with young children, but it's me who usually handles the
lights ;-) Is this a clearcut case for a rewire or is there an easier
way remedy or avoid the problem.

No, its fine, provided you have plastic (or double insulated) light fittings
and switches. Metal switches (and many metal fittings, such as spots/ceiling
fans) are unlikely to comply with this.

However, such a circuit is likely to be old. If done in PVC, there is little
to worry about. However, many old circuits will be done in rubber, which
WILL indicate the need for a rewire.

Christian.

In article ,
(Fred) writes:
Hello,
It appears that my whole lighting circuit has no earth. We are family
of four with young children, but it's me who usually handles the
lights ;-) Is this a clearcut case for a rewire or is there an easier
way remedy or avoid the problem.

If the cable is rubber, then you need to schedule a rewire as a
matter of some urgency, and until then, DON'T TOUCH IT -- any
movement can lead to insulation falling away as a powder, which
is pretty unrepairable except by a rewire. Don't unscrew a
light switch to check this -- look at the wiring in the loft
or somewhere else where you can do so without moving it.

If the insulation is PVC, then you should schedule a rewire, but
it's not necessarily so urgent. What you should do immediately
is make sure all your light switches are plastic (not metal)
faced and the light fittings are all double insulated.

--
Andrew Gabriel

(Andrew Gabriel) wrote:

If the insulation is PVC, then you should schedule a rewire, but
it's not necessarily so urgent. What you should do immediately
is make sure all your light switches are plastic (not metal)
faced and the light fittings are all double insulated.


As someone who has experienced a shock from simultaneously touching a
metal screw retaining a double insulated switch into a metal backbox
that was contacting the live feed, to a metal carpet join strip that I
was standing on in my socks I can confirm it hurts.

Someone ought to provide M3.5 durable plastic screws - but I don't
think they do!

A far more acceptable and viable solution is to install or extend the
RCD to protect the whole house and forget rewiring (unless its rubber)
Of course if you are concerned that loosing all the lights is a
problem then stick a few emergency lights around the place.


--

Someone ought to provide M3.5 durable plastic screws - but I don't
think they do!

You can get plastic caps that clip into the screw holes.

Christian.

As someone who has experienced a shock from simultaneously touching a
metal screw retaining a double insulated switch into a metal backbox
that was contacting the live feed, to a metal carpet join strip that I
was standing on in my socks I can confirm it hurts.

Someone ought to provide M3.5 durable plastic screws - but I don't
think they do!

A far more acceptable and viable solution is to install or extend the
RCD to protect the whole house and forget rewiring (unless its rubber)
Of course if you are concerned that loosing all the lights is a
problem then stick a few emergency lights around the place.

Isn't this advised against in the regulations ? On the basis that if the RCD
were to trip out, you wouldn't want to try and find your fuse box in the
dark ?

"Jethro" wrote in message
...
As someone who has experienced a shock from simultaneously touching a
metal screw retaining a double insulated switch into a metal backbox
that was contacting the live feed, to a metal carpet join strip that I
was standing on in my socks I can confirm it hurts.

Someone ought to provide M3.5 durable plastic screws - but I don't
think they do!

A far more acceptable and viable solution is to install or extend the
RCD to protect the whole house and forget rewiring (unless its rubber)
Of course if you are concerned that loosing all the lights is a
problem then stick a few emergency lights around the place.

Isn't this advised against in the regulations ? On the basis that if the
RCD
were to trip out, you wouldn't want to try and find your fuse box in the
dark ?



I think a small maintained emergency light over the CU (driven from the
circuit that would otherwise provide illumination for the CU) would be a
very good idea in this circumstance.

--
Richard Sampson

mail me at
richard at olifant d-ot co do-t uk

Fred wrote:

Hello,
It appears that my whole lighting circuit has no earth. We are family
of four with young children, but it's me who usually handles the
lights ;-) Is this a clearcut case for a rewire or is there an easier
way remedy or avoid the problem.
Fred

If the wiring is rubber, it will be very old and normally in a
dangerous state, and need rewiring. If its pvc, you have more options:

1. ensure your fittings etc are all either plastic or double insulated

2. Rewire

There is also the option to fit an RCD to the lighting circuit and use
any existing metal fittings. It wont give perfect safety but is a huge
improvement in cases where rewiring is unaffordable. I mention it cos
there are a few in that position.


NT

wrote:

Fred wrote:

Hello,
It appears that my whole lighting circuit has no earth. We are family
of four with young children, but it's me who usually handles the
lights ;-) Is this a clearcut case for a rewire or is there an easier
way remedy or avoid the problem.
Fred

If the wiring is rubber, it will be very old and normally in a
dangerous state, and need rewiring. If its pvc, you have more options:

1. ensure your fittings etc are all either plastic or double insulated

2. Rewire

There is also the option to fit an RCD to the lighting circuit and use
any existing metal fittings. It wont give perfect safety but is a huge
improvement in cases where rewiring is unaffordable. I mention it cos
there are a few in that position.

Good point. Affordability is one issue, a family of four quite
another. Must be one of the worst jobs to get done whilst living in
the house with young children. Found the boiler swap hard enough to
stomach, but going on holidays whilst the electrician rips up all the
floors? Hard to take I must say. Will therefore look into the RCD -
and also consider what other electrics need doing, but it's not
looking good I am afraid.
Fred

In message ,
Shaun wrote:

(Andrew Gabriel) wrote:

If the insulation is PVC, then you should schedule a rewire, but
it's not necessarily so urgent. What you should do immediately
is make sure all your light switches are plastic (not metal)
faced and the light fittings are all double insulated.


As someone who has experienced a shock from simultaneously touching a
metal screw retaining a double insulated switch into a metal backbox
that was contacting the live feed, to a metal carpet join strip that I
was standing on in my socks I can confirm it hurts.

Someone ought to provide M3.5 durable plastic screws - but I don't
think they do!

[...]

There seems to have been a fashion around here at some time in the 1960s
for lighting circuits with no earth, wired through backboxes with
plastic inserts into which the screws for the faceplate screwed. Thus,
although the backbox was metal there was no connection to the metal
screws.

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
Two free issues: http://www.livtech.co.uk/ Living With Technology
.... The wise don't merely stalk their prey, they make the kill.

Will therefore look into the RCD -

Even with a missing earth I wouldn't RCD a lighting circuit, unless it was
required by TT earthing.

Christian.

In article ,
Shaun wrote:
As someone who has experienced a shock from simultaneously touching a
metal screw retaining a double insulated switch into a metal backbox
that was contacting the live feed, to a metal carpet join strip that I
was standing on in my socks I can confirm it hurts.

Someone ought to provide M3.5 durable plastic screws - but I don't
think they do!

Pretty certain RS Components do nylon screws.

However, there's no reason a metal back box should ever be live if the
wiring was well done in the first place.

--
*Never underestimate the power of very stupid people in large groups *

Dave Plowman London SW
To e-mail, change noise into sound.

Christian McArdle wrote:
Will therefore look into the RCD -

Even with a missing earth I wouldn't RCD a lighting circuit, unless
it was
required by TT earthing.

Christian.

I would, benefits outweigh downside, especially with kids, but its only
fair to point out to Fred that if something in the lighting develops or
has already developed an earth fault, which is possible with no earth
wire, you might find the rcd just trips. Its posible. If thats so, its
best you dont use the circuit really.

The main q really is do you have rubber or pvc. If its pvc you shuold
be ok, if its rubber, youve got a mess that needs replacing as soon as
poss.

If its so bad you need to disconnect it, temporary wiring is easy, just
not pretty. If youre stuck, plug in lights are fairly practical.


NT

"Dave Plowman (News)" wrote:

In article ,
Shaun wrote:
As someone who has experienced a shock from simultaneously touching a
metal screw retaining a double insulated switch into a metal backbox
that was contacting the live feed, to a metal carpet join strip that I
was standing on in my socks I can confirm it hurts.

Someone ought to provide M3.5 durable plastic screws - but I don't
think they do!

Pretty certain RS Components do nylon screws.

However, there's no reason a metal back box should ever be live if the
wiring was well done in the first place.

Yes I just noticed they do supply M3.5 but at the time they were
unavailable certainly from the main distributors (Farnell/RS/Vero/STC/
etc) and if I recall correctly one of the major nylon pillar/screw
manufacturers only did M3 and M4

Anyway the whole point was that if the backbox is not earthed then if
as in my case the screw connection to the switch was slightly high
resistance it degraded the insulation gradually (over a period of
10-15 years) This was sufficient to cause contact between the wire and
the backbox - this would have been trivial if non metal screws had
been used or if the backbox had been earthed the MCB/ fuse would have
blown.

I suspect the fault had been there for quite a while though and it was
only accidental simultaneous contact from the fixing screw via sweaty
feet to the carpet strip that was sufficient to be felt - badly
especially as it was a cross chest shock. If I'd been wearing shoes
or been fully on the carpet I doubt there would have been anything
felt at all.


--