Domestic socket loop test puzzle.

[Bobble23]

Hi, I don't know if anyone can help with this. A customer called me out saying that a British Gas boiler service had highlighted a socket showing >2000 on the EFLI test. I went to look and got 1.12 on one side of the (two gang) socket and >2000 on the other. I assumed it was a dodgy socket and replaced it.

Testing the replacement I'm now getting about 1.15 as a loop test when the socket's off the wall but >2000 once I screw it in. I can't find any voltage on the back box.

Any ideas please?

 

[Leesparkykent]

Is this a ring final circuit? If it is have you confirmed continuity end to ends?

 

[westward10]

Somehow earth continuity is breaking down. What do you mean by can't find voltage on the back box.

 

[NDG Elecs]

All I can think of is a dodgy connection on the different test lead or plug adaptor thingy. So you are getting decent-ish reading on the conductors, but a crap reading through a new socket, so have assumed you are using an additional test adaptor or a change of leads to do that test.

 

[Richard Burns]

The initial fault sounds strange as it is difficult to disconnect the earthing from one side of socket but I suppose it is possible, it is more likely (but still unlikely) to have been a damaged earth connector at the socket, e.g. pushed to one side by the plug pin.

Once the socket front has been replaced I woudl assume that there is a poor connection to the earth terminal, perhaps the sleeving is caught on the screw, such that when the conductors are moved as the socket is screwed back the earth disconnects. This would be much more likely if both cpcs are in the same terminal or there is an earth discontinuity on one leg of the ring.

 

[Pat H]

Sounds like the first socket must have been faulty. But the change as the socket is screwed in must be a break in the CPC (s) surely?

 

[stevethesparks]

Maybe the cpc is nor continuous and the leg that does appear to be working has a break in it of which is aggravated when the outlet is pushed into place?

 

[The Ghost]

Are you using plug method and on L-PE? and as others said is it a ring circuit? And what was the gas man doing a loop test for ????

 

[Toneyz]

Are you using plug method and on L-PE? and as others said is it a ring circuit? And what was the gas man doing a loop test for ????

B.G did this with socket tester when they came to service our boiler asked why he said to prove boiler had earth (boiler on own circuit radial)

 

[The Ghost]

This whole thing dont make sense. If the boiler is on own radial then it has a spur yes? Where does the socket come into it? But anyway clearly the earth makes and breaks when the wires are in different position. And anyway a socket tester will not give you an ohmic measurement. Confused I am.

 

[NDG Elecs]

The socket tester that BG used was probably one of those that give a very rough idea of efli: there is one that has measurements something like <1; <5; >5 ohms. So when BG 'measure' it, there is no leeway for TT earthing.

To the OP, is the socket on a stud wall with a socket on the other side of the wall perhaps. The act of screwing back the face plate could be pushing the cable/conductors at an adjacent socket out of position.

Also test the R1 value with the face plate back, as it could be that and not the R2 causing the issue. Although I would suspect the CPC to be the cause.

 

[westward10]

Is there a name for people who start threads and then decide not to respond to anyone's replies.

 

[The Ghost]

Annoying?

 

[Andy78]

Is there a name for people who start threads and then decide not to respond to anyone's replies.

Yes, but the auto filter won't let you write it.

 

[GMES]

He could also have a social life unlike us sad sacks.

 

[Midwest]

Tis a bit rude to ask for advice and not reply. I had to cook the tea last night, but can still find a spare moment.

 

[Leesparkykent]

Tis a bit rude to ask for advice and not reply. I had to cook the dinner last night, but can still find a spare moment.

Corrected that for you mate.......Were have less of that northerner speak

 

[telectrix]

Tis a bit rude to ask for advice and not reply. I had to cook the tea last night, but can still find a spare moment.

you cooked last night and still able to post today. i admire that.

 

[Midwest]

you cooked last night and still able to post today. i admire that.

Well, when I say cooked, I mean walked, yes walked to the chippie & got cod &chips twice.

And wots with all these boxes chippies use now, instead just rolling them up in paper?

 

[Midwest]

Corrected that for you mate.......Were have less of that northerner speak

Can't help it, the old man was from up North. Me Mom was from Barnet, so linguistically it's a frigging nightmare

 

[Wilko]

For me growing up - tea was the name for the evening meal and dinner was lunch - go figure?
Strangely reminds me of "who's on first" -

 

[Toneyz]

This whole thing dont make sense. If the boiler is on own radial then it has a spur yes? Where does the socket come into it? But anyway clearly the earth makes and breaks when the wires are in different position. And anyway a socket tester will not give you an ohmic measurement. Confused I am.

Sorry if my post confused you the point that I was trying to make is regardless of this earth fault to socket B.G plugged their socket loop tester in the socket on our landing to prove earth however our boiler is on its own radial not the ring so not actualy proving earth of the boiler circuit.Going back to the socket earthing problem,unless the cables of the live or earth are trapped by the insulation there must be a break in the cable that is make/breaking as being moved.

 

[westward10]

Don't think we will find out any time soon.

 

[The Ghost]

who's on first

That was great. I remember I think in arabian nights was it? the conversation about the lotion and the potion that the little guy had to put in someones room, been trying to find that clip for ages, dont spose you have it? I will understand if you aint got a clue what I'm on about

 

[Bobble23]

Thanks for the replies all (and sorry for getting back late - you really don't want to know about the weekend I've just had!).

I'm using the socket attachment for my MFT and haven't had any problems with it before so doubt that that's the problem.

The socket in question is a spur from the washing machine RFC socket below. I originally agreed with Steve and thought there was maybe a break in the cable which was made when the socket's pushed back into place. However, when the socket is off the wall the loop test is fine, but even if I don't screw it back but instead connect with 1mm wire the earth of the socket to the earth terminal on the box the reading jumps to >2000 Ohms. Afraid I can't get my head round it at all.

 

[Pete999]

Clutching at straws, but you only have one cable at the socket with the problem, yes? can you gain access or do you know where it is spurred from? if you do can you disconnect that spur cable and check for continuity, making sure the wires are not broken anywhere, I did say clutching at straws that's all I can add.

 

[Jay Sparks]

Clutching at straws, but you only have one cable at the socket with the problem, yes? can you gain access or do you know where it is spurred from? if you do can you disconnect that spur cable and check for continuity, making sure the wires are not broken anywhere, I did say clutching at straws that's all I can add.

This is why I tell my apprentices to test at EVERY point on the circuit when doing continuity. Even though you can see the cpc, doesn't mean it's really there! It could be broken inside the sheath (if using multi core of course).

Jay

 

[Bobble23]

Thanks Pete. I'll try that when I go back but I'm not optimistic - the cpc is there and tests up except when it has any sort of contact with the back box. It's in the kitchen - maybe I should tell the customer to look for a battery-powered toaster!

 

[westward10]

Give the cpc a good pull, if it comes away there is your problem.

 

[The Ghost]

Have you tried moving the socket about when you test? Clearly there is no logic in

connect with 1mm wire the earth of the socket to the earth terminal

causing a break in the loop. therefore the single you attached has pulled in the socket enough to re-create the pushing the socket back into the box and replicated the same break. And as Westward10 asked "what do you mean voltage on the back box" maybe there is a clue there?