I'm looking at reinstating a 15A spur to a socket in our kitchen for an
oven. The previous owner had an all gas cooker which (I guess) whould
just have been plugged into the ring main for any leckie it needed.

There's an existing cable with plenty slack terminated under the kithen
floor connected though to a 15A fuseway in the fusebox. The cable looks
quite old, slightly heavier than 2.5mm2 (based on my vernier
measurement) and the earth is twisted steel (?) strand rather than
solid copper.

I'm pretty sure I'm going to rip it out and run a new cable just to be
sure, but before I go to all the trouble (and it will be a lot of
trouble) is there anyway to test the integrity of the existing cable?

How do I tell if it's got the old friable insulator on it?

"urchaidh" wrote in message
oups.com...
I'm looking at reinstating a 15A spur to a socket in our kitchen for an
oven. The previous owner had an all gas cooker which (I guess) whould
just have been plugged into the ring main for any leckie it needed.

There's an existing cable with plenty slack terminated under the kithen
floor connected though to a 15A fuseway in the fusebox. The cable looks
quite old, slightly heavier than 2.5mm2 (based on my vernier
measurement) and the earth is twisted steel (?) strand rather than
solid copper.

I'm pretty sure I'm going to rip it out and run a new cable just to be
sure, but before I go to all the trouble (and it will be a lot of
trouble) is there anyway to test the integrity of the existing cable?

How do I tell if it's got the old friable insulator on it?

Don't chance it either way. Renew it and be sure it's safe. Old tinned
cable isn't going to be near the present requirements for the wiring, so
it's cheaper, safer and lots less hassle to replace it all while the jobs
opened up to see it all.

To test the integrity fully means expensive meters and megers. It's not
worth the expensive on one cable mate, believe me. Just take a look on the
web for "Electrical Insulation Tester" and you'll see what I mean.

"urchaidh" wrote in message
oups.com...
I'm looking at reinstating a 15A spur to a socket in our kitchen for an
oven. The previous owner had an all gas cooker which (I guess) whould
just have been plugged into the ring main for any leckie it needed.

There's an existing cable with plenty slack terminated under the kithen
floor connected though to a 15A fuseway in the fusebox. The cable looks
quite old, slightly heavier than 2.5mm2 (based on my vernier
measurement) and the earth is twisted steel (?) strand rather than
solid copper.

Are the circuit conductors stranded or solid?
The old 7/029 or thicker cables often had tinned copper conductors. You may
be mistaking tinned copper for steel if you are basing your idea on colour.
Steel conductors would be very unusual and easily confirmed with a magnet.

I'm pretty sure I'm going to rip it out and run a new cable just to be
sure, but before I go to all the trouble (and it will be a lot of
trouble) is there anyway to test the integrity of the existing cable?

The conductor continuity can be checked with a low resistance tester, the
insulation value can be easily checked with a Megger. Unfortunately you
should also inspect the condition and verify there are no branches or spurs
off it and it is in good/satisfactory condition (no rodent or other damage)
This may not be possible:-(

How do I tell if it's got the old friable insulator on it?

With your eyes and try bending it to see if bits crack and falls off. If its
anything but PVC or MICC you should chuck it anyway. You can of course use
it as a pull wire to draw in a new cable

Kitchens are special locations under the fat controllers new regs and
require notification of ANY work to building control. Proper Testing and
Certification is required.

urchaidh wrote:
I'm looking at reinstating a 15A spur to a socket in our kitchen for an
oven.
There's an existing cable with plenty slack terminated under the kithen
floor connected though to a 15A fuseway in the fusebox. ...
I'm pretty sure I'm going to rip it out and run a new cable just to be
sure, but before I go to all the trouble (and it will be a lot of
trouble) is there anyway to test the integrity of the existing cable?

Don't bother. Put in a new cable and use 10mm while you're at it. That
will be ample for anything anyone is likely to want to run off it in the
future. Leave spare length at each end. (The fusebox can be upgraded
later if needed, but putting in the bigger cable now will save the
disruption later.)

Owain

In article .com,
urchaidh wrote:
I'm looking at reinstating a 15A spur to a socket in our kitchen for an
oven. The previous owner had an all gas cooker which (I guess) whould
just have been plugged into the ring main for any leckie it needed.

There's an existing cable with plenty slack terminated under the kithen
floor connected though to a 15A fuseway in the fusebox. The cable looks
quite old, slightly heavier than 2.5mm2 (based on my vernier
measurement) and the earth is twisted steel (?) strand rather than
solid copper.

Probably 7/0.29 line and neutral and 3/0.29 earth. Tin plated copper.

If PVC insulated quite likely to still be in perfectly serviceable
condition. If rubber - not.

I'm pretty sure I'm going to rip it out and run a new cable just to be
sure, but before I go to all the trouble (and it will be a lot of
trouble) is there anyway to test the integrity of the existing cable?

Just about all cables deteriorate most where they are terminated. So if it
looks in good condition at the ends it should be fit for further service -
if PVC.

How do I tell if it's got the old friable insulator on it?

Rubber verses PVC?

However, you say you wish to run an oven off it. As a radial?
Many ovens may be just plugged into the ring main. Those that can't
usually require rather more than a 15 amp feed, for which this cable
wouldn't be suitable.

--
*Be nice to your kids. They'll choose your nursing home.

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

Dave Plowman (News) wrote:
In article .com,
urchaidh wrote:

I'm looking at reinstating a 15A spur to a socket in our kitchen for an
oven. The previous owner had an all gas cooker which (I guess) whould
just have been plugged into the ring main for any leckie it needed.

There's an existing cable with plenty slack terminated under the kithen
floor connected though to a 15A fuseway in the fusebox. The cable looks
quite old, slightly heavier than 2.5mm2 (based on my vernier
measurement) and the earth is twisted steel (?) strand rather than
solid copper.

Probably 7/0.29 line and neutral and 3/0.29 earth. Tin plated copper.

If PVC insulated quite likely to still be in perfectly serviceable
condition. If rubber - not.

I'm pretty sure I'm going to rip it out and run a new cable just to be
sure, but before I go to all the trouble (and it will be a lot of
trouble) is there anyway to test the integrity of the existing cable?

Just about all cables deteriorate most where they are terminated. So if it
looks in good condition at the ends it should be fit for further service -
if PVC.

How do I tell if it's got the old friable insulator on it?

Rubber verses PVC?

However, you say you wish to run an oven off it. As a radial?
Many ovens may be just plugged into the ring main. Those that can't
usually require rather more than a 15 amp feed, for which this cable
wouldn't be suitable.


Condition test: bend the exposed ends, after isolating them. If it
doesnt crack, its ok mechanically.

A bit of basic electronics makes it easy to insulation test. dioe and
capacitor from mains gives 330v. 2 of those gives +330 and -330, a
total of 660v difference. Add a cheap meter set to current range and
you get a reading of any leakage current at 660v. Or a fried =A35 meter.

To do that youd need to be competent enough to regard it as obvious how
that would be connected up, that it is live working, and that it must
be disconnected from CU and insulated from people cats etc. If not,
leave well alone.

CPC resistance test: parallel N and L conductors at one end, and join
all 3 at other end. Now youve got 3 strands of CPC and 14 strands of
phase. Now:

Total R =3D Rphase + Rcpc.
And we know that Rcpc =3D 3/14 x Rphase.
thus total R =3D (1 + 3/14) x Rcpc.

Rcpc =3D 0.82 x Rtotal.


A much easier option is to get someone with a PAT tester to come test
its Rtotal (to work out Rcpc) and insulation. If necessary.


I'm only saying this because the OP indicated it would be a grim job to
replace, and theres no need to replace if it works fine. It might well
be plastered in here there and everywhere, and require removing fitted
stuff to get to it, replaster etc. Theres nowt wrong with using old
wire iff its in good condition and upto the job, and sometimes it is.


NT

In article .com,
wrote:
I'm only saying this because the OP indicated it would be a grim job to
replace, and theres no need to replace if it works fine. It might well
be plastered in here there and everywhere, and require removing fitted
stuff to get to it, replaster etc. Theres nowt wrong with using old
wire iff its in good condition and upto the job, and sometimes it is.

Yes - I recently found some dead 7/029 PVC in my house and removed it. It
was in perfect condition.

--
*The man who fell into an upholstery machine is fully recovered.*

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

Dave Plowman (News) wrote:
In article .com,
urchaidh wrote:
I'm looking at reinstating a 15A spur to a socket in our kitchen for an
oven. The previous owner had an all gas cooker which (I guess) whould
just have been plugged into the ring main for any leckie it needed.

However, you say you wish to run an oven off it. As a radial?
Many ovens may be just plugged into the ring main. Those that can't
usually require rather more than a 15 amp feed, for which this cable
wouldn't be suitable.

Yeah, it'll have to be a 13A oven with a plug. I thought I might add an
extra radial (on a spare 15A fuseway) for it rather than have it on the
kitchen ring main.

Would that have to be 20A fuseway? In that case I guess I could make it
a proper radial and have another socket on it for the fridge (20m2
kitchen, 30m cable). Then if I ever upgrade the CU I could have an RCD
on the kithen ring main, MCB only for the cooker/fridge.

To many options! Should I just plug the 13A oven it into the kithen
ring and the job is done.

I can never see me wanting a leckie hob so I doubt that I'd bother with
the whole 10mm2 dedicated cooker radial.

In article .com,
urchaidh wrote:
However, you say you wish to run an oven off it. As a radial?
Many ovens may be just plugged into the ring main. Those that can't
usually require rather more than a 15 amp feed, for which this cable
wouldn't be suitable.

Yeah, it'll have to be a 13A oven with a plug. I thought I might add an
extra radial (on a spare 15A fuseway) for it rather than have it on the
kitchen ring main.

Would that have to be 20A fuseway? In that case I guess I could make it
a proper radial and have another socket on it for the fridge (20m2
kitchen, 30m cable). Then if I ever upgrade the CU I could have an RCD
on the kithen ring main, MCB only for the cooker/fridge.

To many options! Should I just plug the 13A oven it into the kithen
ring and the job is done.

I can never see me wanting a leckie hob so I doubt that I'd bother with
the whole 10mm2 dedicated cooker radial.

Has the kitchen got its own ring? If not, would it be feasible to use this
cable to do that? Then modify the rest of the ground one into a new ring?

It obviously depends on where your CU is and accessibility under floors,
etc.

--
*Funny, I don't remember being absent minded.

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

Dave Plowman (News) wrote:
In article .com,
urchaidh wrote:
However, you say you wish to run an oven off it. As a radial?
Many ovens may be just plugged into the ring main. Those that can't
usually require rather more than a 15 amp feed, for which this cable
wouldn't be suitable.

Yeah, it'll have to be a 13A oven with a plug. I thought I might add an
extra radial (on a spare 15A fuseway) for it rather than have it on the
kitchen ring main.

Would that have to be 20A fuseway? In that case I guess I could make it
a proper radial and have another socket on it for the fridge (20m2
kitchen, 30m cable). Then if I ever upgrade the CU I could have an RCD
on the kithen ring main, MCB only for the cooker/fridge.

To many options! Should I just plug the 13A oven it into the kithen
ring and the job is done.

I can never see me wanting a leckie hob so I doubt that I'd bother with
the whole 10mm2 dedicated cooker radial.

Has the kitchen got its own ring? If not, would it be feasible to use this
cable to do that? Then modify the rest of the ground one into a new ring?

The kitchen has its own ring, just finished that sorting that out. I
didn't do a diversity calcualtion for load, but my tendancy to
over-engineer led me to the idea of a second dedicated spur for the
oven, even though it will be a sub 13A device on a socket.

Am I being overcomplicated, should I just plug in the oven to the ring?


It obviously depends on where your CU is and accessibility under floors,
etc.

Access around the kitchen is fine and easy as I have the floors up at
the moment and it's going to be replastered soon. From the kitchen to
the CU is a real PITA. The CU is an old sytlee fuse box. Upgrading it
is on the list. Cables from the last possible accessable point in the
hall to the CU are well buried in the wall.

urchaidh wrote:

The kitchen has its own ring, just finished that sorting that out. I
didn't do a diversity calcualtion for load, but my tendancy to
over-engineer led me to the idea of a second dedicated spur for the
oven, even though it will be a sub 13A device on a socket.

Am I being overcomplicated, should I just plug in the oven to the ring?

Well, many houses are done like this, and it works ok in practice.


It obviously depends on where your CU is and accessibility under floors,
etc.

Access around the kitchen is fine and easy as I have the floors up at
the moment and it's going to be replastered soon. From the kitchen to
the CU is a real PITA. The CU is an old sytlee fuse box. Upgrading it
is on the list. Cables from the last possible accessable point in the
hall to the CU are well buried in the wall.

In that case I would seriously consider using the cable to run a
dedicated feed to the fridge freezer, not the oven. Put this feed on a
non RCDed line, if youre not TT. Now an RCD trip wont cost you your
freezer contents. Kitchens contain the majority of the prime RCD
tripping items.


NT