Testing cabling

[Pocster]

I’ve almost completed the socket wiring install 1st fix for the ground floor .

Is there any way I can test each part of the cable ?

My concern is that it’s not impossible to imagine that a screw has gone through a cable . Rather than have everything wired up and find the fault it would be much easier to rectify a cable issue now at this stage .

So for example in the pics ...

Test the cable coming into the socket at ‘this’ end - and where it goes into the next socket .

Edited January 10, 2020 by pocster

[SteamyTea]

Take your pick.

https://www.test-meter.co.uk/multifunction-testers/

 

Have you documented the installation method?

 

Or just plug it in with a very low amperage fuse in place.

Or, lick your right index finger and flick it across the earth and neutral.

 

Get a sparky in.

[Mr Punter]

With the sockets you could strip the cable ends and use wagos x3 to join earth-earth, live-live, neutral-neutral.

 

You could then short all the wires one end and test for continuity the other end.

 

A sparky will probably post soon with a much better suggestion.

[Pocster]

  On 10/01/2020 at 13:57, Mr Punter said:

With the sockets you could strip the cable ends and use wagos x3 to join earth-earth, live-live, neutral-neutral.

 

You could then short all the wires one end and test for continuity the other end.

 

A sparky will probably post soon with a much better suggestion.

Expand  

Yeah I was thinking that . But would say a screw through a cable be picked up with this method ? I.e you’d still have continuity.

[Pocster]

  On 10/01/2020 at 13:53, SteamyTea said:

Take your pick.

https://www.test-meter.co.uk/multifunction-testers/

 

Have you documented the installation method?

 

Or just plug it in with a very low amperage fuse in place.

Or, lick your right index finger and flick it across the earth and neutral.

 

Get a sparky in.

Expand  

Document the installation!!!! ????????????????

 

That’s a no . A sparky will check my work though .... 

[Carrerahill]

  On 10/01/2020 at 13:49, pocster said:

I’ve almost completed the socket wiring install 1st fix for the ground floor .

Is there any way I can test each part of the cable ?

My concern is that it’s not impossible to imagine that a screw has gone through a cable . Rather than have everything wired up and find the fault it would be much easier to rectify a cable issue now at this stage .

So for example in the pics ...

Test the cable coming into the socket at ‘this’ end - and where it goes into the next socket .

Expand  

Are you keeping your wires within prescribed areas and immediately horizontal or vertical of any switch or socket? I am not trying to be that annoying twit that just pokes, I only ask as the top image shows a wire but no apparent outlet/device to give someone the indication a wire may be present. Photograph everything before you sheet over (or are we too late for that?). I even wrote on sheets as I installed them the distances from walls, and plotted out danger zones. When it comes to installing the kitchen in particular I will lightly re-plot these out across the whole kitchen double checked with a wire finder so that there is no excuse for hitting a wire!

 

For testing, there are various tests from very basic to more advanced.

 

As a starter do basic continuity test, as said above, Wago the wires together at one end, and bell them out at the other.  This can test for breaks and shorts, but not for a nail or screw which has penetrated a single core and no other.

 

 

Edited January 10, 2020 by Carrerahill

[Markblox]

Good idea to test it. The regs say "test during and on completion", and it isn't supposed to be optional!  These dead tests include continuity and insulation resistance tests and the IR uses a specialist tester and you also  need to know how to use it and with rings it is also a bit complex re the continuity test so I would advise you use wago's as previously described and get the sparks in who is going to sign off the work to test it because he will need to record the results on the installation certificate. Doing it this way will also give you piece of mind and will mean when you energise the circuits you don't have to worry about a bang or the RCD tripping which is always a good thing.

Also good point re cable position.

[MrMagic]

Typically first fix is just get the wires in and leave them normally untested. Then when you're counting down the weeks to move in you'll find a nail or screw through your cooker circuit or something and have to smash a big hole in the wall to get at it... ?

[MrMagic]

  On 10/01/2020 at 15:52, Markblox said:

These dead tests include continuity and insulation resistance tests and the IR uses a specialist tester

Expand  

 

Yep, IR is the test that'll show up the gremlins.. even little things like dragging a cable through or over something causing a nick in the insulation is enough to warrant further investigations (depending on the reading).

 

Don't be tempted just to pull a cable through or over a joist, feed with one and guide/pull with the other.... I know this is common sense for most people but I've seen T&E back to bare copper when installed badly - rip and replace in some instances.

[Ed Davies]

  On 10/01/2020 at 13:53, SteamyTea said:

Take your pick.

https://www.test-meter.co.uk/multifunction-testers/

Expand  

 

Totally OTT for the basic cable integrity checks needed here for which a basic multimeter would be fine. Yes, in theory you might have abrasion on the cable or a screw through it just next to a conductor which won't show anything on the meter but which will break down at 500 V on a mega but the chances of that are so slim that you're better off putting up with the tiny risk that it'll happen and not be detected until the sparks does the proper testing after second fix.

[Ed Davies]

Personally, I'd use a longish bit of flex. Connect one end to the end of the cable to be checked (e.g, with @Mr Punter's Wagos), L-L, N-N, E-E, and take the other end to the other end of the cable then check with a meter continuity L-L, N-N, E-E and discontinuity L-N, N-E, E-L. Checking the discontinuities actually looking at the resistances (on a highish range) might be better than just relying on it not beeping but I'm not sure I'd bother.

[Markblox]

  On 10/01/2020 at 16:03, MrMagic said:

 

Yep, IR is the test that'll show up the gremlins.. even little things like dragging a cable through or over something causing a nick in the insulation is enough to warrant further investigations (depending on the reading).

 

Don't be tempted just to pull a cable through or over a joist, feed with one and guide/pull with the other.... I know this is common sense for most people but I've seen T&E back to bare copper when installed badly - rip and replace in some instances.

Expand  

I remember at college the tutor saying that 60% of wiring faults occur on installation and cable burn must be high up the list.

 

Although Part P is designed for the electrician to design, install, test and certify installation, unless I'm wrong (entirely possible), a three part certificate can always be used where the design, installation and testing has separate signatures. The regs don't say that you must be qualified but do say you must be a  competant person. Please give me your thoughts as to the three sig cert as I don't know the score with a domestic installation.

Edited January 10, 2020 by Markblox

[Markblox]

  On 10/01/2020 at 16:14, Ed Davies said:

Personally, I'd use a longish bit of flex. Connect one end to the end of the cable to be checked (e.g, with @Mr Punter's Wagos), L-L, N-N, E-E, and take the other end to the other end of the cable then check with a meter continuity L-L, N-N, E-E and discontinuity L-N, N-E, E-L. Checking the discontinuities actually looking at the resistances (on a highish range) might be better than just relying on it not beeping but I'm not sure I'd bother.

Expand  

That may well show up dead shorts but not faults that would trip a circuit breaker, RCD or start a fire.

The insulation resistance test uses 500V to make sure the electrons don't jump from one conductor to another. Also the test results have to appear on the certificate.

[Pocster]

  On 10/01/2020 at 15:39, Carrerahill said:

Are you keeping your wires within prescribed areas and immediately horizontal or vertical of any switch or socket? I am not trying to be that annoying twit that just pokes, I only ask as the top image shows a wire but no apparent outlet/device to give someone the indication a wire may be present. Photograph everything before you sheet over (or are we too late for that?). I even wrote on sheets as I installed them the distances from walls, and plotted out danger zones. When it comes to installing the kitchen in particular I will lightly re-plot these out across the whole kitchen double checked with a wire finder so that there is no excuse for hitting a wire!

 

For testing, there are various tests from very basic to more advanced.

 

As a starter do basic continuity test, as said above, Wago the wires together at one end, and bell them out at the other.  This can test for breaks and shorts, but not for a nail or screw which has penetrated a single core and no other.

 

 

Expand  

Hey!

All wires run vertical to all sockets. You spotted that odd one as it's just a pull cord cable so I can pull a tv ariel feed in there later.

[Markblox]

  On 10/01/2020 at 16:08, Ed Davies said:

 

Totally OTT for the basic cable integrity checks needed here for which a basic multimeter would be fine. Yes, in theory you might have abrasion on the cable or a screw through it just next to a conductor which won't show anything on the meter but which will break down at 500 V on a mega but the chances of that are so slim that you're better off putting up with the tiny risk that it'll happen and not be detected until the sparks does the proper testing after second fix.

Expand  

The proper testing should be done during  and on  completion . Not just after second fix.

[ProDave]

As a minimum, insulation test every run of cable L-E and N-E.  That should show up a screw through the cable.  Then all 3 to building earth, that should show a screw that just grazed a single core.

 

I am wiring a new build at the moment, and everything was fine before the plasterboarders came.  Shortly after they finished boarding, they found a stud wall in the wrong place so took it down to move it, and found 2 cables with screws through them.  I am expecting grief with the rest of this house.  Why is it NONE of the other building trades have the slightest idea of the concept of "safe zones" and keep their screws out of them?

[Ed Davies]

  On 10/01/2020 at 16:23, Markblox said:

That may well show up dead shorts but not faults that would trip a circuit breaker, RCD or start a fire.

The insulation resistance test uses 500V to make sure the electrons don't jump from one conductor to another. Also the test results have to appear on the certificate.

Expand  

 

  On 10/01/2020 at 16:27, Markblox said:

The proper testing should be done during  and on  completion . Not just after second fix.

Expand  

 

Right. Of course the proper testing will have to be done at some time by somebody who is qualified to do it; this is just an exercise to reduce the risk of having to rework other stuff and waste the sparks time if there is a cable fault.

 

I did write “after second fix” when perhaps I should have written “when the sparks is on site for second fix”.

[Oz07]

Since when do sparks come back to test during works?! @Markblox

[Markblox]

  On 10/01/2020 at 16:40, Ed Davies said:

 

 

Right. Of course the proper testing will have to be done at some time by somebody who is qualified to do it; this is just an exercise to reduce the risk of having to rework other stuff and waste the sparks time if there is a cable fault.

 

I did write “after second fix” when perhaps I should have written “when the sparks is on site for second fix”.

Expand  

 

  On 10/01/2020 at 16:41, Oz07 said:

Since when do sparks come back to test during works?! @Markblox

Expand  

Not often, but they should do it after first fix to prove no faults exist. Lot of extra work so they usually don't bother and faults are often found a lot later or latent faults are never found as a result. 

[Jeremy Harris]

  On 10/01/2020 at 14:35, pocster said:

Document the installation!!!! ????????????????

 

That’s a no . A sparky will check my work though .... 

Expand  

 

 

How is the electrician who signs this off going to be able to sign to say that he has seen all of the cable runs, that all are in compliance with the requirements, including supports, clipped securely at not more than the maximum allowable cable clip spacing, cable physical protection provided where required, cables in both the right zones and at least 50mm below surfaces, no serviceable connections in inaccessible locations etc?

 

Is the electrician going to lie when he "signs" the IEC and states that he/she can confirm that all wiring is run as per the requirements?

[Onoff]

Problems with your ring? Live by the sword etc! ?

[ProDave]

  On 10/01/2020 at 16:48, Markblox said:

 

Not often, but they should do it after first fix to prove no faults exist. Lot of extra work so they usually don't bother and faults are often found a lot later or latent faults are never found as a result. 

Expand  

The problem with that, is at first fix it is typically a bare timber frame, or quite often the stud walls boarded one side only.  Everything is fine when I leave after first fix.

 

Then along come the bufoons who fit the plasterboard , followed almost immediately by the plasterer.  By the time I get a chance to see if the bufoons have damaged a cable it's too late to do anything anyway, so it all waits for second fix to find the issues.  They don't even have the gumption to look at the wall they are boarding and observe where the cables are and avoid screws at that position.

[Markblox]

  On 10/01/2020 at 16:41, Oz07 said:

Since when do sparks come back to test during works?! @Markblox

Expand  

Well most don't.  They pull all sorts of strokes and maybe it is so common that others think that is the right way.  It doesn't make it right and it doesn't make it safe, just normal.

[ProDave]

  On 10/01/2020 at 16:57, Markblox said:

Well most don't.  They pull all sorts of strokes and maybe it is so common that others think that is the right way.  It doesn't make it right and it doesn't make it safe, just normal.

Expand  

Why is it not safe?  as long as proper testing is done at the end in what way is it unsafe because he may not have come and re tested at some intermediate point in the build?

[Markblox]

  On 10/01/2020 at 16:59, ProDave said:

Why is it not safe?  as long as proper testing is done at the end in what way is it unsafe because he may not have come and re tested at some intermediate point in the build?

Expand  

Yes, if proper testing is done then fair enough, but as you know there is often so little testing done. The only time all tests are or should be carried out is when the install is new but I have seen new installs fired up and left with a so called tester arriving a few days later and plugging in a socket and see and basically making up the rest of the info. Unbelievable but I'm sure you have seen all that before now Dave.