Can I confirm how to test for and how to find a borrowed neutral?

[HappyHippyDad]

During some testing I found a N-E IR fault on the kitchen lights of 0.1Mohms. I also found a N-E IR fault on the ring sockets, again 0.1Mohms.

This could have been a coincidence, but I disconnected both neutrals from the neutral bar (i.e the kitchen lights and sockets) and tested between them. They showed continuity (0.97 ohms). Just FYI, there was no continuity with these neutrals to the neutrals of the other circuits.

This is a dual RCD board. K lights and sockets on the same side.

Does the fact the neutrals showed continuity mean this is a borrowed neutral? I have not come across continuity between neutrals before. Is this the correct test for them? Does it actually mean they are connected together somewhere, or am I missing other possibilities?

Also, as the neutrals have been connected together somewhere in the house between these 2 circuits, how do I find this join? The house is full of shoddy DIY alterations. I would like to offer at least a guess as to how you find this join, but for the life of me I cannot think of a way.

 

[7029 dave]

What he means is there are two different scenarios:
A) no neutral there at all so one is stolen from elsewhere (like your conservatory light example)
B) two neutral conductors from different circuits are joined (what this thread is about and not really a borrowed neutral. All my ideas for what we could call this don’t get past the language filter….

That is more of an interconnection than a borrowed neutral IMO

 

[Dave OCD]

I dont think so! Keep taking the pills if you think a screw has gone through 2 different cables. Im assuming you dont do much domestic stuff.

There's really no need for that attitude - particularly towards such a highly respected member with more knowledge than you could ever get close to.

 

[davesparks]

I dont think so! Keep taking the pills if you think a screw has gone through 2 different cables. Im assuming you dont do much domestic stuff.

Why couldn't a screw have gone through 2 different cables?

 

[mainline]

A pair of cables running along a ceiling joist could both get penetrated.
Hanging a light fitting, if you used long screws and only caught the edge of the joist you could easily cause an N-N short, and maybe also cause a resistance to the CPC at the same time.

The same goes for cables in partitions.


A bit more info on the type of house/size etc maybe of help.

 

[HappyHippyDad]

Well, I must apologise as I shall not be returning to the customer, so I will not be able to update. I've just had the most odd conversation with him on the phone and he does not want me back. Bit shocked as that hasn't happened before. As in the opening post, he was a very difficult man to deal with but I wasn't expecting that.

His reasons were that I miss diagnosed a faulty cooker and I left the loft lights on!

I'm not a 100% sure I didn't miss diagnose the cooker. The cooker itself showed 0.1Mohms N-E. Is this perhaps acceptable for some cookers? Its an older looking rangemaster. Even so, bit harsh!

Happy not to be going back though, he was a very un pleasant man and shockingly rude to his very pleasant wife.

Oh yes, and he isn't going to pay for the 2 hours fault finding or fixing his 3 kitchen lights. I will not be going to the small claims for a £100 and shall take it on the chin, albeit a little grumpily

The neutral problem will remain and we shall never know!!!

 

[DPG]

Well, I must apologise as I shall not be returning to the customer, so I will not be able to update. I've just had the most odd conversation with him on the phone and he does not want me back. Bit shocked as that hasn't happened before. As in the opening post, he was a very difficult man to deal with but I wasn't expecting that.

His reasons were that I miss diagnosed a faulty cooker and I left the loft lights on!

I'm not a 100% sure I didn't miss diagnose the cooker. The cooker itself showed 0.1Mohms N-E. Is this perhaps acceptable for some cookers? Its an older looking rangemaster. Even so, bit harsh!

Happy not to be going back though, he was a very un pleasant man and shockingly rude to his very pleasant wife.

Oh yes, and he isn't going to pay for the 2 hours fault finding or fixing his 3 kitchen lights. I will not be going to the small claims for a £100 and shall take it on the chin, albeit a little grumpily

The neutral problem will remain and we shall never know!!!

Sounds like you're better off out of it.

 

[SJD]

Happy not to be going back though, he was a very un pleasant man and shockingly rude to his very pleasant wife.

Perhaps the real reason for not wanting you back is he has read your post #23 !

 

[timhoward]

It would be brilliant if the next sparks he calls happens to be a member on here.....
Personally I'd take great delight in telling him this is a tricky job and needs an expert - there's a guy I know that specialises in this kind of thing, probably the only guy for miles around that stands any chance of working it out for you....and then give him HHD's number....!

 

[123]

Well, I must apologise as I shall not be returning to the customer, so I will not be able to update. I've just had the most odd conversation with him on the phone and he does not want me back. Bit shocked as that hasn't happened before. As in the opening post, he was a very difficult man to deal with but I wasn't expecting that.

His reasons were that I miss diagnosed a faulty cooker and I left the loft lights on!

I'm not a 100% sure I didn't miss diagnose the cooker. The cooker itself showed 0.1Mohms N-E. Is this perhaps acceptable for some cookers? Its an older looking rangemaster. Even so, bit harsh!

Happy not to be going back though, he was a very un pleasant man and shockingly rude to his very pleasant wife.

Oh yes, and he isn't going to pay for the 2 hours fault finding or fixing his 3 kitchen lights. I will not be going to the small claims for a £100 and shall take it on the chin, albeit a little grumpily

The neutral problem will remain and we shall never know!!!

Better off rid of him.

I'm confused though, 0.1M Ohms N-E Fault on sockets, lights and the cooker as well?

 

[Lucien Nunes]

If anything is likely to be giving a 0.1 meg fault it's the cooker. But clearly HHD tested around the lighting and socket circuits carefully, hence discovering the interconnection between them, so it seems most unlikely that he mis-identified which circuit(s) had low IR. I agree it's a bit peculiar.

The cooker itself showed 0.1Mohms N-E. Is this perhaps acceptable for some cookers? Its an older looking rangemaster.

It's entirely possible due to moisture in elements that don't get used often. The figure is likely to be very variable. I bet if you turned all the rings and oven on for 30 minutes, it would go down first, maybe trip the RCD, then up and away into the megohms as the moisture dissipates, only to fall again over time. Whether that constitutes a fault or a pathology of sheathed heating elements is a matter of semantics. Of course it could also be a 'real' fault like charred insulation but that would be a rare exception.

Keep taking the pills if you think a screw has gone through 2 different cables. Im assuming you dont do much domestic stuff.

I haven't touched domestic for 25 years, but I did see this happen once. Cooker circuit and ring under capping in a chase badly out of safe zone, cupboard fixing screw had connected (IIRC) the ring line to the cooker neutral.

I'm sad that we won't get to hear the resolution and that you won't get the satisfaction of rectifying it. One of the things I found when I often used to get hired as a specialist fault-finder, was that I would go into a job subconsciously expecting an endorphin buzz at the end of it. If that didn't happen, e.g. because we couldn't get access or it was a 2-minute fix which the guy on the spot should have dealt with, it would dent my enthusiasm for a while.

 

[HappyHippyDad]

Sorry, I posted a little too quickly. The figure of 0.1M ohms was for the interconnected sockets/lights. This figure sprang to kind when I was posting regarding the cooker, because it was imprinted on my brain regards the sockets/lights.
I can't find my results now, but I believe the cooker results were lower, how much lower I just can't remember.

 

[marconi]

Well, I must apologise as I shall not be returning to the customer, so I will not be able to update. I've just had the most odd conversation with him on the phone and he does not want me back. Bit shocked as that hasn't happened before. As in the opening post, he was a very difficult man to deal with but I wasn't expecting that.

His reasons were that I miss diagnosed a faulty cooker and I left the loft lights on!

I'm not a 100% sure I didn't miss diagnose the cooker. The cooker itself showed 0.1Mohms N-E. Is this perhaps acceptable for some cookers? Its an older looking rangemaster. Even so, bit harsh!

Happy not to be going back though, he was a very un pleasant man and shockingly rude to his very pleasant wife.

Oh yes, and he isn't going to pay for the 2 hours fault finding or fixing his 3 kitchen lights. I will not be going to the small claims for a £100 and shall take it on the chin, albeit a little grumpily

The neutral problem will remain and we shall never know!!!

As a professional civil engineer he would expect to be paid for his services and similarly so should you. At the very least send him a bill spelling out the work and cost with your bank details and terms for settlement eg within x days of date of bill. He is trying to brow beat you in area of engineering he is incompetent and unqualified. And then follow up with a polite phone call after x days. You are not a charity. What is the make and reg of car on their drive?

 

[ipf]

You are not a charity. What is the make and reg of car on their drive?

Do you mean the one with the flat tyres?

 

[Penguin]

During some testing I found a N-E IR fault on the kitchen lights of 0.1Mohms. I also found a N-E IR fault on the ring sockets, again 0.1Mohms.

This could have been a coincidence, but I disconnected both neutrals from the neutral bar (i.e the kitchen lights and sockets) and tested between them. They showed continuity (0.97 ohms). Just FYI, there was no continuity with these neutrals to the neutrals of the other circuits.

This is a dual RCD board. K lights and sockets on the same side.

Does the fact the neutrals showed continuity mean this is a borrowed neutral? I have not come across continuity between neutrals before. Is this the correct test for them? Does it actually mean they are connected together somewhere, or am I missing other possibilities?

Also, as the neutrals have been connected together somewhere in the house between these 2 circuits, how do I find this join? The house is full of shoddy DIY alterations. I would like to offer at least a guess as to how you find this join, but for the life of me I cannot think of a way.

Please ensure that your IR test is to the Lighting Switch and NOT through their loads…!!!!!

Unless of course you’ve disconnected ALL DC down lights, Flori units, etc etc.

This will otherwise go badly wrong, and resistance tests.