I recently had an electrical problem where a short on a lighting
circuit in the loft caused my radiators and water taps to become live.

Obviously the plumbing is inadequately earthed, which I will remedy.
Additionally, a short-circuit tripped my (very old) trip switch. I
called an electrician, who sucked air through his teeth and told me
that all of the old rubber-insulated wiring in my house (both lighting
circuits and one ring main) would need to be rewired. He also took out
the fuses from the lighting circuits (which he said were reading very
low insulation levels), and fitted a 30mA RCB for the entire house.

I am wondering whether he took the best course of action. Might my old
rubber-insulated wiring still be serviceable? If so, could I simply
rewire the shorted/failing sections (which are in the loft and easily
accessible)? I'm worried that if I try to do this, my old lighting
circuit will not work with the newly fitted 30 mA RCB.

Will such a repair be possible, and if so, what are the risks
associated with it? Will it be safe?

Will a qualified electrician undertake repairs like I've described, or
will they require me to rewire the whole house!?

Will a house with (functional) rubber insulated wiring pass an
electrical safety inspection for e.g. renting?

Thanks for any help or advice.

Best wishes

Harry

On 2 Feb 2006 10:29:34 -0800, Harry wrote:

Might my old rubber-insulated wiring still be serviceable?

Absolutely, categorically, no.

--
Nigel M

Harry wrote:

I recently had an electrical problem where a short on a lighting
circuit in the loft caused my radiators and water taps to become live.

Obviously the plumbing is inadequately earthed, which I will remedy.

Sounds like an understatement!

Additionally, a short-circuit tripped my (very old) trip switch. I
called an electrician, who sucked air through his teeth and told me
that all of the old rubber-insulated wiring in my house (both lighting
circuits and one ring main) would need to be rewired. He also took out
the fuses from the lighting circuits (which he said were reading very
low insulation levels), and fitted a 30mA RCB for the entire house.

I am wondering whether he took the best course of action.

Not quite sure if I follow the bit about removing fuses... The RCD ought
to save your life should something similar happen in the near future. I
would make sure you heve plenty of smoke alarms as well.

Might my old
rubber-insulated wiring still be serviceable?

Not a chance - you are living on borrowed time.

*You may not get another warning*

Will such a repair be possible,

might be

and if so, what are the risks
associated with it?

Your house bursts into flames or you get eletrocuted.

Will it be safe?

Nope

Will a qualified electrician undertake repairs like I've described,

I would hope not.

or will they require me to rewire the whole house!?

yes

Will a house with (functional) rubber insulated wiring pass an
electrical safety inspection for e.g. renting?

In your case no - you have already said that it is failing insulation
resistance checks.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
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| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Thank you both for your feedback. I will get on the case urgently (by
removing the fuses, I meant that I have cut off both lighting circuits
until I can resolve the issue - I am however still running power
through one rubber insulated circuit - see below).

The one ring main circuit which has rubber insulated wiring passed the
insulation resistance checks easily (the electrician said three times
the suggested minimum), and has caused no problems. In spite of this,
should I still be seeking to replace it, and how urgently?

Thanks again for the advice
Harry

Harry wrote:
Thank you both for your feedback. I will get on the case urgently (by
removing the fuses, I meant that I have cut off both lighting circuits
until I can resolve the issue - I am however still running power
through one rubber insulated circuit - see below).

The one ring main circuit which has rubber insulated wiring passed the
insulation resistance checks easily (the electrician said three times
the suggested minimum), and has caused no problems. In spite of this,
should I still be seeking to replace it, and how urgently?

Yes.
Rubber not only degrades in terms of insulation resistance, it also
becomes crumbly, and degrades physically to the extent that any
disturbance at all can cause it to fail.
This could be as little as a mouse walking over it, causing a failure.

This probably has a fairly small chance (under 10%) of actually causing
a fire, if the circuit is properly designed.

If it's not, and the wire is a bit small, then a fire is more likely.
It will probably fail some time in the next couple of decades.

Harry formulated on Thursday :
I recently had an electrical problem where a short on a lighting
circuit in the loft caused my radiators and water taps to become live.

1st warning bell!

Obviously the plumbing is inadequately earthed, which I will remedy.
Additionally, a short-circuit tripped my (very old) trip switch. I
called an electrician, who sucked air through his teeth and told me
that all of the old rubber-insulated wiring in my house (both lighting
circuits and one ring main) would need to be rewired. He also took out
the fuses from the lighting circuits (which he said were reading very
low insulation levels), and fitted a 30mA RCB for the entire house.

I'm surprised he was willing to even touch it at all. He could well
have decided the whole lot was such a risk it needed to be disconnected
from the supply without further delay.


I am wondering whether he took the best course of action. Might my old
rubber-insulated wiring still be serviceable?

Not a chance.

If so, could I simply
rewire the shorted/failing sections (which are in the loft and easily
accessible)?

You could, but it would be a complete waste of time.


Will such a repair be possible, and if so, what are the risks
associated with it? Will it be safe?

Safe? absolutely not. The risks... The place going up in smoke possibly
your insurance refusing to pay out. Risks of death and/or serious
injury.


Will a qualified electrician undertake repairs like I've described, or
will they require me to rewire the whole house!?

An odd job man might do it, but certainly not someone with a reputation
and qualifications to guard.

Will a house with (functional) rubber insulated wiring pass an
electrical safety inspection for e.g. renting?

Highly unlikely. The safety should be taken even more seriously if your
intention is to put someone elses life at risk, than your own.

--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

On 2 Feb 2006 10:29:34 -0800, "Harry" wrote:

He also took out
the fuses from the lighting circuits (which he said were reading very
low insulation levels), and fitted a 30mA RCB for the entire house.

I'm surprised he left you any fuses at all.

I am wondering whether he took the best course of action. Might my old
rubber-insulated wiring still be serviceable?

What part of "NO" are you having the trouble with?

On 2 Feb 2006 12:27:31 -0800, "Harry" wrote:

Thank you both for your feedback. I will get on the case urgently (by
removing the fuses, I meant that I have cut off both lighting circuits
until I can resolve the issue - I am however still running power
through one rubber insulated circuit - see below).

The one ring main circuit which has rubber insulated wiring passed the
insulation resistance checks easily (the electrician said three times
the suggested minimum), and has caused no problems. In spite of this,
should I still be seeking to replace it, and how urgently?

Thanks again for the advice
Harry

Whilst I agree that the rubber has to go and that without any doubt,
the lighting circuits WILL be in an extemely dangerous state, I
removed the last two rubber insulated rings from my house last spring,
admittedly the kitchen load had already been removed and so they were
both lightly loaded but they were in a perfectly serviceable
condition, with no sign whatsoever of brittleness, even after 50 years
since the house was built, and so I would suggest that condition very
much depends on location.

Having said all that, you should get it replaced ASAP.

Andy

"Harry" wrote in message
oups.com...
Thank you both for your feedback. I will get on the case urgently (by
removing the fuses, I meant that I have cut off both lighting circuits
until I can resolve the issue - I am however still running power
through one rubber insulated circuit - see below).

The one ring main circuit which has rubber insulated wiring passed the
insulation resistance checks easily (the electrician said three times
the suggested minimum), and has caused no problems. In spite of this,
should I still be seeking to replace it, and how urgently?

Rubber insulated wire has a service life of 20 years, but has not been
installed for at least twice that long. Any rubber insulated cable should be
replaced immediately and it would be very advisable to pull the fuses on any
circuit using it until it has been replaced.

Colin Bignell

On 2 Feb 2006 10:29:34 -0800
"Harry" wrote:

I recently had an electrical problem where a short on a lighting
circuit in the loft caused my radiators and water taps to become live.
snip

IANAE (I am not an electrician)

Some 20 years ago I moved into a 1930's semi. I knew when I bought it
that it would need rewiring as it had just two 15 Amp (round pin) power
sockets, plus the cooker point and lighting. The fuseboard didn't even
have a 'consumer unit', just a couple of Steel and Ceramic fuse boxes -
I wish I had taken a photo.

Well, on the morning of moving in, I checked the insulation resistance
with a megger and immediately condemned the lot - pulled the fuses and
went down to the local Electrical Dealer to buy a consumer unit and
lots of cable and so on. I tacked 2.5 T&E to the skirting to wire
up a couple of double 13Amp sockets, and put in two lights over the
stairs and in the kitchen. Then, illegally and probably foolishly, I
moved the meter tails to the new CU - I even had SWMBO standing by to
stop anyone making a loud noise while I did it. But I could sleep at
night until the full rewire was done.

When I started the rewire proper I found rubber dust in steel conduit
buried in the hair plaster - the wires were just hanging there - bare!
Where the conduits ended there were rubber 'boots' on the end to prevent
chafing of the isulation on the sharp metal - hard and crumbly. Now I
assume that the rubber was intact until I disturbed it, but a passing
truck could have done that. I stood and shivered for some time after
the discovery.

Don't mess with Rubber Insulation.

R.

Andy Cap wrote:
On 2 Feb 2006 12:27:31 -0800, "Harry" wrote:

Thank you both for your feedback. I will get on the case urgently (by
removing the fuses, I meant that I have cut off both lighting circuits
until I can resolve the issue - I am however still running power
through one rubber insulated circuit - see below).

snip
Whilst I agree that the rubber has to go and that without any doubt,
the lighting circuits WILL be in an extemely dangerous state, I
removed the last two rubber insulated rings from my house last spring,
admittedly the kitchen load had already been removed and so they were
both lightly loaded but they were in a perfectly serviceable
condition, with no sign whatsoever of brittleness, even after 50 years
since the house was built, and so I would suggest that condition very
much depends on location.

And maybe even batch of rubber, or age.
Then there's the issue of - if you've got 1950s wiring in, did the
electrician completely rip out all the 1940s stuff, or is there some
going through that hard to drill wall.

Harry wrote:

The one ring main circuit which has rubber insulated wiring passed the
insulation resistance checks easily (the electrician said three times
the suggested minimum), and has caused no problems.

I would not take too much comfort from that. The minimum is 250K ohms -
with decent insulation you would expect a reading of at least tens of
meg ohms with modern PVC insulated wire. Rubber when new would have
probably been higher still.

In spite of this,
should I still be seeking to replace it, and how urgently?

Yes, within the month.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Richard A Downing wrote:
On 2 Feb 2006 10:29:34 -0800
"Harry" wrote:

I recently had an electrical problem where a short on a lighting
circuit in the loft caused my radiators and water taps to become live.
snip

IANAE (I am not an electrician)

Some 20 years ago I moved into a 1930's semi. I knew when I bought it
that it would need rewiring as it had just two 15 Amp (round pin) power
sockets, plus the cooker point and lighting. The fuseboard didn't even
have a 'consumer unit', just a couple of Steel and Ceramic fuse boxes -
I wish I had taken a photo.

Well, on the morning of moving in, I checked the insulation resistance
with a megger and immediately condemned the lot - pulled the fuses and
went down to the local Electrical Dealer to buy a consumer unit and
lots of cable and so on. I tacked 2.5 T&E to the skirting to wire
up a couple of double 13Amp sockets, and put in two lights over the
stairs and in the kitchen. Then, illegally and probably foolishly, I
moved the meter tails to the new CU - I even had SWMBO standing by to
stop anyone making a loud noise while I did it. But I could sleep at
night until the full rewire was done.

When I started the rewire proper I found rubber dust in steel conduit
buried in the hair plaster - the wires were just hanging there - bare!
Where the conduits ended there were rubber 'boots' on the end to prevent
chafing of the isulation on the sharp metal - hard and crumbly. Now I
assume that the rubber was intact until I disturbed it, but a passing
truck could have done that. I stood and shivered for some time after
the discovery.

Don't mess with Rubber Insulation.

R.

20 years ago it was not uncommon to find old rubber installations. As
often as not, removing a fitting would reveal what Richard describes,
bare L&N wires twisting around each other with only air and the
remaining lumps of broken down rubber for spacers. And that was 20
years ago.


NT

Harry wrote:
Thank you both for your feedback. I will get on the case urgently (by
removing the fuses, I meant that I have cut off both lighting circuits
until I can resolve the issue - I am however still running power
through one rubber insulated circuit - see below).

The one ring main circuit which has rubber insulated wiring passed the
insulation resistance checks easily (the electrician said three times
the suggested minimum), and has caused no problems. In spite of this,
should I still be seeking to replace it, and how urgently?

Thanks again for the advice
Harry


Given the overall condition of the install, which is evidently
terrible, yes it all needs replacing. If youre getting bit by the
radiators, you quite likely have no earth on the system, which is a
relatively serious risk. If so, connecting rads and taps to what you
think is earth wont make the least difference.

There are also risks not yet mentioned. If you rent this property, jail
time would be a very real risk, following the death of your tenant. You
also run the risk of being prosecuted on less dramatic grounds.

If it were mine I'd disconnect the lot at the CU, fit a few sockets on
new wire, and use extension leads taped out of the way until it was all
done. And that would be an ideal time to replace the CU too, with a
split job. (note if your supply is TT then both CU halves will need an
RCD)

If perchance its round pin, which I doubt, I know someone who would
make a sensible use of the old plugs and sockets.


NT

On 03 Feb 2006 10:47:53 GMT, Ian Stirling
wrote:

they were in a perfectly serviceable
condition, with no sign whatsoever of brittleness, even after 50 years
since the house was built, and so I would suggest that condition very
much depends on location.

And maybe even batch of rubber, or age.
Then there's the issue of - if you've got 1950s wiring in, did the
electrician completely rip out all the 1940s stuff, or is there some
going through that hard to drill wall.

In my particular case, it was a new build at that time and I know
there is now no rubber left anywhere in the house.

Andy

Andy Cap wrote:
On 03 Feb 2006 10:47:53 GMT, Ian Stirling
wrote:

they were in a perfectly serviceable
condition, with no sign whatsoever of brittleness, even after 50 years
since the house was built, and so I would suggest that condition very
much depends on location.

And maybe even batch of rubber, or age.
Then there's the issue of - if you've got 1950s wiring in, did the
electrician completely rip out all the 1940s stuff, or is there some
going through that hard to drill wall.

In my particular case, it was a new build at that time and I know
there is now no rubber left anywhere in the house.

True, I was more using the generic 'you', rather than just referring to
your case.

wrote in message
oups.com...
....
20 years ago it was not uncommon to find old rubber installations. As
often as not, removing a fitting would reveal what Richard describes,
bare L&N wires twisting around each other with only air and the
remaining lumps of broken down rubber for spacers. And that was 20
years ago.

In the early 1970s, I was taken to check the lift installation at an
Electricity Board area office, by the senior engineer in charge of the
engineering department at that office. The rules required two people to be
present, for safety. I lightly touched the woven cloth sheath of the
flexible cable that dropped down the length of the shaft and connected the
lift to the control gear and heard a sound like dry leaves rustling. The
senior engineer decided that we would not investigate that cable any
further.

Colin Bignell

In article ,
"nightjar" nightjar@insert my surname here.uk.com writes:

In the early 1970s, I was taken to check the lift installation at an
Electricity Board area office, by the senior engineer in charge of the
engineering department at that office. The rules required two people to be
present, for safety. I lightly touched the woven cloth sheath of the
flexible cable that dropped down the length of the shaft and connected the
lift to the control gear and heard a sound like dry leaves rustling. The
senior engineer decided that we would not investigate that cable any
further.

In my university hall of residence, we had to put up with
the best part of a year with no lifts whilst they were being
reconditioned (which did include complete replacement of the
motors and lifting gear, so it was quite substantial). The
lifts, although in appearence unchanged, same cars, etc, were
much faster. However, it only lasted about 2 months before
the trailing cable to a lift cage caught fire. That was
apparently about the only item which hadn't been replaced.
The fire pretty much wrote off the lift cars, and left the
top two floors of the building completely black and smelling
of burning car tires. It was a few weeks before the top
floors were cleaned up to the point people could use them,
and another year before the lifts were working again.

--
Andrew Gabriel

"John Rumm" wrote in message
...
Harry wrote:

The one ring main circuit which has rubber insulated wiring passed the
insulation resistance checks easily (the electrician said three times
the suggested minimum), and has caused no problems.

I would not take too much comfort from that. The minimum is 250K ohms -
with decent insulation you would expect a reading of at least tens of meg
ohms with modern PVC insulated wire. Rubber when new would have probably
been higher still.


I think you will find the minimum is 500K at 500V.

Steve Dawson

Stephen Dawson wrote:

"John Rumm" wrote in message
...

Harry wrote:


The one ring main circuit which has rubber insulated wiring passed the
insulation resistance checks easily (the electrician said three times
the suggested minimum), and has caused no problems.

I would not take too much comfort from that. The minimum is 250K ohms -
with decent insulation you would expect a reading of at least tens of meg
ohms with modern PVC insulated wire. Rubber when new would have probably
been higher still.



I think you will find the minimum is 500K at 500V.

Yes sorry you are right. Its 250K @ 250V for SELV and PELV circuits,
500K @ 500V for ordinary LV (240V) ones.

To the OP, your 3x absolute minimum is still below the recommended
minimum of 2M ohms.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 2 Feb 2006 12:27:31 -0800, Harry wrote:

how urgently?

Put it this way.

Rather than reading any more replies, get on the phone.

--
Nigel M