Advice needed for less experienced electrician.

[Davisonp]

Hi,

I have been asked to move some plug sockets from the skirting board (they are too low and this causes problems plugging in equipment) to higher up the wall in a domestic property. I will be chasing in and fitting new flush mounted sockets.

I am after advice on the best way to proceed. There seems to be several options. If the cable under the floor is long enough to reach the new socket position, then there will be no need to extend any cables and no major problems, but if it is not long enough, what is the best method for extending it? NOTE: The cable is in good condition so a full rewire is not necessary due to deterioration as it appears to have been changed in the late 70’s or early 80’s.

To get to the new socket if the cables are too short, I had planned either to use Hagar Maintenance free junction boxes, with the idea of spurring off the ring under the floorboards and having a single new cable to the new sockets, or I could extend both legs of the ring by crimping each conductor then putting the joint in a “chock box” for strain relief and to enclose the uncovered insulation. What is the best practice for extending cables in this circumstance?

Also, I think the best option for the chasing in and putting in the back coxes may be to take my equipment into a room (with three or four sockets) and do them together, then move all the equipment onto another room or location and do another group of sockets in the area. Is this a good plan, or is there a better way to do this?

 

[sparks1973]

It’s a TNS system, and at the moment, there are two consumer units one with MCB’s supplying the kitchen extension and the lighting, and the other ( an old Mem wooden box) with 30 Amp fuses supplying the two ring mains for upstairs, downstairs and a 15 amp fuse for the boiler radial. The old MEM box has had a cupboard built round it so now you can only open the lid just enough to get the fuse out, but you cannot get access to the wires at all.
I have explained the benefits of RCD’s to the client, and that I cannot test the ring circuit as I cannot access the cables without damaging the consumer unit, so the first job here is to change the two consumer units for a single 17[SUP]th[/SUP] edition, giving me chance to run the standard tests on the rings and radial while changing the unit.

you can break out the cables for the ring final at a convenient point (outlet)..for your end to end resistances....and can also cross em for R1 R2 at the outlet...it doesn`t need to be at the C/U....same for IR....

 

[Davisonp]

look, if the existing install has been done by someone with the foresight....they will have left enough cable looped under floors in order to pull em up........

Yes, if they have thought ahead, but the sockets in the skirting boards have no back boxes, they are chiselled out to the point where the socket just fits in the gap and is held in by the size of the hole. The screws are just for show, they screw into the woodwork.
Is this normal for skirting board sockets? Or do most of them have back boxes?

 

[Hobsoni]

Well, it's a variable that can be interpreted in many different ways. For me, anything inaccessible usually means it's 'hidden' (this is again open to debate) and the second discription I would use would be anything that I determine to be 'hard work' to access, like taking up floorboards (lol).

In this instance a JB under the floor would tick both boxes. I have heard some electricians say that a JB in the loft is deemed 'inaccessible' if the loft doesn't have a dedicated ladder affixed to it! For me, thats questionable.

 

[Hobsoni]

Skirting sockets done 'properly'.......I use this term cautiously as I think it's improper placement for a socket in the first place. Either they have a metal conduit going into a metal back box fixed behind the Skirt or they are plastic external back boxes.

It sounds like a bit of a bodge job to me, if they have not used ANY back box.

 

[sparks1973]

Yes, if they have thought ahead, but the sockets in the skirting boards have no back boxes, they are chiselled out to the point where the socket just fits in the gap and is held in by the size of the hole. The screws are just for show, they screw into the woodwork.
Is this normal for skirting board sockets? Or do most of them have back boxes?

it sounds like an old install...14th or15th...my mothers house had some switches for the wall lights installed in the skirting like this....
well, as for if it was acceptable then....cant be sure....
you wouldn`t do it now of course....

 

[sparks1973]

Skirting sockets done 'properly'.......I use this term cautiously as I think it's improper placement for a socket in the first place. Either they have a metal conduit going into a metal back box fixed behind the Skirt or they are plastic external back boxes.

It sounds like a bit of a bodge job to me, if they have not used ANY back box.

you woudn`t need metal conny going into the knockout box....
a lot of councils used to wire their housing stock with conny n singles though...

 

[sparks1973]

if using existing cable then be sure to zap it first wont you...before reusing it..just to be sure....thats before you change the C/U (when you will of course be testing it again)...last thing you need is to be testing for the C/U change...only to find that 1 (or more) legs of the old stuff is low...

 

[Hobsoni]

it sounds like an old install...14th or15th...my mothers house had some switches for the wall lights installed in the skirting like this....
well, as for if it was acceptable then....cant be sure....
you wouldn`t do it now of course....

Going by what is being said, I think if you delve deeper into this one you could find a few more bits of trickery that wouldn't fill you with confidence. To me it's showing all the signs of there being no earth in the lighting circuits............and then you have to change the board as well now.............so your going to have to find a solution to the lighting etc etc..................and then you will be a bit panicky as you only went to move a socket............and now its a re-wire.

Maybe i'm being facetious but the customer will be thinking about procrastination if my outlook proves correct??

 

[sparks1973]

the state of the existing cable`s insulation will be dependant on age and how much fault its been subjected to over time....
so a good giveaway would be to inspect the fuse carrier for that circuit....
if theres loads of splash in it....or evidence of numerous disconnections....you may find the IR comes back low.....
this is of course not cast in stone but its often a giveaway....

 

[sparks1973]

well a way round the no CPC in the lighting cable will be solved when the new C/U goes on...RCDs yes...
another alternative open to you is to use some 4mm CSA earth cable from point to point on the offending lighting circuit.....this can then be taken back to the MET or a convenient point (you would need to verefy that the CPC used is capable of handling the extra fault for disconnection times)....just watch the class 1s though wont you...
dont forgrt that BS7671 referes to there being a means of earthing AT EVERY POINT` within an installation.....
not that every cable needs a CPC

 

[Hobsoni]

Maybe I'm misunderstood, but I didn't think an RCD solely being fitted was a satisfactory way of overcoming a circuit with no cpc's? If in the regs it does state this, then i must apologise to a certain Mr.......... who I made sure had earthing installed as well as an RCD.

Ultimately, your name is on there to sign off the said works...........If your not confident, then you don't do it. However, we all have to start somewhere............i agree with sparks1973...........slap 4mm protective earth cable in rather than the smaller CSA's that would probably suffice.

 

[Davisonp]

you can break out the cables for the ring final at a convenient point (outlet)..for your end to end resistances....and can also cross em for R1 R2 at the outlet...it doesn`t need to be at the C/U....same for IR....

Yes, I did not try too hard to get these readings as the consumer unit is going to be changed, which gives a good opportunity to perform these tests at that time. The one test you cannot do from the back of a socket is IR between neutral and CPC as they are joined together at the transformer for TNS systems.
I did try and look behind several sockets, but they were so tightly jammed into the skirting that there was a real risk of breaking them, so the few sockets I could get access to were not easy to get at so I decided to wait for the consumer unit change for the circuit tests and I just checked the connections, visually checked the cable and put them back.

 

[Davisonp]

Skirting sockets done 'properly'.......I use this term cautiously as I think it's improper placement for a socket in the first place. Either they have a metal conduit going into a metal back box fixed behind the Skirt or they are plastic external back boxes.

It sounds like a bit of a bodge job to me, if they have not used ANY back box.

I agree.

 

[Hobsoni]

[QUOTE=Davisonp;632463. The one test you cannot do from the back of a socket is IR between neutral and CPC as they are joined together at the transformer for TNS systems.

Is the main switch on the board not double pole? The neutral will be isolated when you have the power off to perform the pre-commisioned tests? Although, I always IR test from the consumer unit.

 

[DPG]

Theoretically speaking, having a single cable spurred to a socket off a ring main JB, how would this differ from spurring off of a ring main socket? Or for that matter, spurring out of the circuit breaker of a ring main? I admit, it's not something I would go 'looking' to do....................but is it really as bad as your making out?

I maye be wrong here but I didn't think you could have more spur sockets than there are sockets on the ring. Using your method, all the sockets would be spur sockets, unless I'm misreading things. Daz