Kitchen cable 4mm or Imperial?

[kingeri]

Hi all, this is my first post so go easy on me!

Now, this may be a really stupid question, but if I don't ask then it'll just bug me.

I have recently been doing some general decorating in the kitchen and before I go too far, I want to have the wiring checked over. It looks pretty old to me. It appears to be a radial circuit with a branch. The cable leaves the CU and then goes to a JB. One branch from this JB then goes to two double sockets at one side of the kitchen, and the other branch supplies a double socket and combi boiler (with a 3a fused switch) at the other side of the kitchen. The circuit breaker is 16amp. The problem is that I occasionally get nuisance tripping (16a ain't a lot for a kitchen!).

So my question is, is this layout ok? I am considering upping to a 32a breaker but I know I can't if I don't have the right cable in place. The problem I'm having is being sure what the cable is. It's red & black and is much thicker than 2.5mm T&E. The live and neutral consist of 7 twisted wires each whilst the earth is solid and not much thicker than one of the strands from the other cables. It seems that it is much beefier than 2.5mm that feeds the ring finals in the house. Is this 4mm cable? My dad (a retired gas fitter) has had a look at it and says it could be old Imperial cable.

On an unrelated issue....is it acceptable for a ring main to span two floors of a house (2 bedrooms plus as loft conversion), so long as the max. floor space and cable lengths are not exceeded?

 

[PC Electrics]

If you look in the downloads section you will see a guide to imperial cables which I uploaded ages ago. Download the guide and obtain a vernier caliper and you will be able to identify the cable. We cannot possibly do so from the other side of a computer screen.

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http://www.talk.electricianforum.co.uk/electrician-talk-forum/7583-imperial-t-e-cable-ratings-4-u-all.html

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http://www.talk.electricianforum.co.uk/electrician-talk-forum/7583-imperial-t-e-cable-ratings-4-u-all.html

 

[tom1]

good idear to get wiring checked over befor decorating ect, many people dont. when the spark comes too check it he will easily be able to work out the cable size and replace your 16amp with a 20 or 32 amp mcb after considering other factors like length of circuit ect

 

[ProDave]

Another good clue to age, is are they bare copper cores, or are they tinned (silvery colour) The older ones tended to be tinned.

Since there are doubts about this particular circuit, and you are about to decorate, is now not a good time to rewire the kitchen and get it done properly once and for all?

It's probably unlikely that you will be able to beyond a 20A circuit breaker (once you have determined the cable size) so I suspect nuisance tripping will remain until you can rewire it as a proper ring final with a 32A circuit breaker.

But of course that opens up the can of worms about RCD's and Part P.

 

[sparkytim]

sounds like 7/029 imperial cable

If used as a radial then 20 A protection will protect it.

A Ring final circuit can supply more then one floor and as many sockets as you like over max floor area proscribed

 

[PC Electrics]

IF it is 7/029, then it is rated at 31A so could be put on a 25A MCB (install method permitting) which ought to reduce or eliminate nuisance tripping.

Even a 20A would be better than 16. You cn pull 26A through one for 15 mins

 

[kingeri]

Thanks guys. If it did turn out to be 4mm, would a 32a breaker be ok?

 

[Zeespark]

It would be fine.

AndyGuinness

 

[kerching]

...or you could be really unlucky and it is copperclad. Used in the mid seventies it is ali cable with a copper coating. It was and is total and utter carp of the first order. It was always sized 'up a size' so, 4mm was used instead of 2.5mm. ...the strands snap off as soon as you look at them

 

[SLIPSHOD & SLAPDASH]

I am sure imperial had a stranded earth which would mean this is 4mm ?

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erm :Blushing

From 14th edition

 

[kingeri]

The spark who initially looked at the cable was about 20 years old. It was obvious to me that he didn't know what it was. He actually made an excuse not to do the job. Do they still teach new sparks about retro cabling? Forums like this are obviously invaluable.......as with anything you can't beat experience.

 

[kerching]

Columns 3 and 4 refer to flat 2 and 3 core and earth cable with a metal sheath [lead?]......5 and 6 refer to flat twin rubber or PVC sheath............how old is that book??....don't think that I have ever seen lead, rubber and PVC on the same page.[except in some of the fringe Adult Special Interest publications... :innocent ].......... :coat

 

[Zeespark]

Kingeri, students these days arent even taught how to fabricate trunking/cable tray, let alone older elements of installation.

AndyGuinness

 

[kingeri]

I am really interested in retraining as an electrician. I just don't know how to go about it, being thirty-odd and working full time. Is it even worth it in todays economic climate?

 

[kerching]

Columns 3 and 4 refer to flat 2 and 3 core and earth cable with a metal sheath [lead?]......5 and 6 refer to flat twin rubber or PVC sheath............how old is that book??....don't think that I have ever seen lead, rubber and PVC on the same page.[except in some of the fringe Adult Special Interest publications... :innocent ].......... :coat

Just seen 14th edition at bottom of table, whoops

 

[kingeri]

ROTFWL true

 

[Doc Hudson]

Welcome to the forum. Irrespective of what size the cable is or isn't you will need to test the insulation resistance and maximum earth loop impedance before even considering uprating the fuse. But at a guess I doubt there would be many problems uprating to 20A,

Doc H.

 

[kingeri]

Welcome to the forum. Irrespective of what size the cable is or isn't you will need to test the insulation resistance and maximum earth loop impedance before even considering uprating the fuse. But at a guess I doubt there would be many problems uprating to 20A,Doc H.

You're right. I think I'm thinking like a typical amateur. Just wish one of you guys lived near me! Should be able to search for a sparky on experience as well as area! ?:|

 

[philbas]

The spark who initially looked at the cable was about 20 years old. It was obvious to me that he didn't know what it was. He actually made an excuse not to do the job. Do they still teach new sparks about retro cabling? Forums like this are obviously invaluable.......as with anything you can't beat experience.

No they don't.

On the other hand how far can you retro teach ? You could fill the enite course time telling them about the 16th , the 15th, the 14th etc.

Do new accountants get taught about Pounds, Shillings and Pence, I very much doubt it, but they may run into it.

What should be taught is the theory and principles, from that you should be able to do a bit of research, apply the theory and come to a conclusion !

Measure the CSA of the cables, apply the theory, do the calculations, then you can work out if its ok.

What seems to happen is an automatic reply, 2.5mm for sockets, 1.5 for lights, thats what is taught but do they understand why?

At least thats my opinion.

And I'm not even an electricion

 

[batty]

I am really interested in retraining as an electrician. I just don't know how to go about it, being thirty-odd and working full time. Is it even worth it in todays economic climate?

I would say stick with what you are doing you could spend a fortune on retraining and then not find a job. There just is not the work out there at the moment.