Some advice please

[hightower]

Went to see the 72-year-old Dad of a teacher at the school because his electric has been tripping. Get there to be told he's had issues with it since he moved in six years ago but it's getting progressively worse.

TT system, single RCD for the whole board, so when it trips it takes the lot. So I get to testing IR on the board, both L-E and N-E readings are kicking about 2-3Mohms. I tested globally first, then starting to test individually each circuit in the hope of finding a single fault. Every circuit except the shower circuit was reading 2-3Mohms L-E and N-E. The shower tested >200, so I can only assume it was a newer install, especially since it's MCB didn't match the rest of the board make/model wise.

So by now I'm at the conclusion that there's a general breakdown of the insulation of the whole install. I fire it all back up and clamp the earth - it was ticking over at 10mA constant but peaked at around 20mA for a brief second a couple of times. While clamped I turned MCBs off one at a time to see what impact each circuit had, and they all contributed in some way or another.

So hopefully after reading this, you're at the same conclusion as me - rewire needed.

However, that's where it gets tricky. The guy is 72, is in ill health (meningitis, recent stroke and heart attack, brain tumour, blind in one eye - basically a ticking time bomb), and he's not sure what to do. I suggested perhaps it could prolong the inevitable to change the board to DP RCBOs so that there's less current for each device - hopefully stopping tripping, or at least if it does trip it'll be isolated to one circuit and won't be without all electricity.

So I need some advice. I said it needs a rewire ideally, but don't want to push him down that path when he could be dead tomorrow - it's a lot of money as well as disruption for someone of such ill health. What would you do:

• Only accept a rewire, walk away if not
• Happily change the board in the hope it gets a little more life from the aging wiring
• Something else

Thanks for your thoughts on this, bit of a pickle.

 

[Leesparkykent]

I would fit a SBS compact RCBO board.

 

[Pete999]

Went to see the 72-year-old Dad of a teacher at the school because his electric has been tripping. Get there to be told he's had issues with it since he moved in six years ago but it's getting progressively worse.

TT system, single RCD for the whole board, so when it trips it takes the lot. So I get to testing IR on the board, both L-E and N-E readings are kicking about 2-3Mohms. I tested globally first, then starting to test individually each circuit in the hope of finding a single fault. Every circuit except the shower circuit was reading 2-3Mohms L-E and N-E. The shower tested >200, so I can only assume it was a newer install, especially since it's MCB didn't match the rest of the board make/model wise.

So by now I'm at the conclusion that there's a general breakdown of the insulation of the whole install. I fire it all back up and clamp the earth - it was ticking over at 10mA constant but peaked at around 20mA for a brief second a couple of times. While clamped I turned MCBs off one at a time to see what impact each circuit had, and they all contributed in some way or another.

So hopefully after reading this, you're at the same conclusion as me - rewire needed.

However, that's where it gets tricky. The guy is 72, is in ill health (meningitis, recent stroke and heart attack, brain tumour, blind in one eye - basically a ticking time bomb), and he's not sure what to do. I suggested perhaps it could prolong the inevitable to change the board to DP RCBOs so that there's less current for each device - hopefully stopping tripping, or at least if it does trip it'll be isolated to one circuit and won't be without all electricity.

So I need some advice. I said it needs a rewire ideally, but don't want to push him down that path when he could be dead tomorrow - it's a lot of money as well as disruption for someone of such ill health. What would you do:

• Only accept a rewire, walk away if not
• Happily change the board in the hope it gets a little more life from the aging wiring
• Something else

Thanks for your thoughts on this, bit of a pickle.

Tricky one Mate, has the Old Gent got any Relations you can approach? sorry for the short reply that's about all I can advise, get the Family involved, that's what I would do, save any accusations that you fleeced the Old Chap.

 

[GMES]

@hightower
I do hate to hear stories like this but we also have to rise to these challenges and look for the best solution, firstly I would agree with Lee's idea and then maybe think about rewiring one circuit at a time, maybe one a week or something like that to keep the disruption, upset and mess to a minimum.
As a last resort is there nowhere he could go and stay for a week while it got done in one go, also I love the idea that on this forum we have a mulitude of great sparks and generous members, wouldn't it be great to get 10-20 of us together and blitz the place in one go and also supply all the gear, it would cost hardly anything per man to get it accomplished.
Now I don't know the location but I would be willing to put my money where my mouth is and offer a couple of my lads for a couple of days free of charge and start the kitty off with £ 100.00 towards the materials.

I did similar a couple of years ago the day before xmas eve some lowlifes had ripped an old guy off and left his house in a right state he had no heating and the db swap was lethal, we sorted all the wiring out and heating free of charge and got him sorted for christmas, The look on his face when it was done was worth every bit of it.

Give me a shout if you need the help and let's see if we can't sort it out for the Guy and see if any other members are up for the challenge.

 

[hightower]

Out shooting so will reply in a bit.

 

[hightower]

I would fit a SBS compact RCBO board.

Well that was my thinking. Even though the IR is 2-3Mohms on each circuit, I was thinking an RCBO board might delay the inevitable. I just wanted a second opinion to sort of say it wouldn't be a bodge job.

Tricky one Mate, has the Old Gent got any Relations you can approach? sorry for the short reply that's about all I can advise, get the Family involved, that's what I would do, save any accusations that you fleeced the Old Chap.

Yep, I did explain as much as I could to the guy, but he did seem a little confused in areas. I said I'd speak to his daughter on Thursday when I'm back at the school and explain everything to her so they can make a decision together.

@hightower
I do hate to hear stories like this but we also have to rise to these challenges and look for the best solution, firstly I would agree with Lee's idea and then maybe think about rewiring one circuit at a time, maybe one a week or something like that to keep the disruption, upset and mess to a minimum.
As a last resort is there nowhere he could go and stay for a week while it got done in one go, also I love the idea that on this forum we have a mulitude of great sparks and generous members, wouldn't it be great to get 10-20 of us together and blitz the place in one go and also supply all the gear, it would cost hardly anything per man to get it accomplished.
Now I don't know the location but I would be willing to put my money where my mouth is and offer a couple of my lads for a couple of days free of charge and start the kitty off with £ 100.00 towards the materials.

I did similar a couple of years ago the day before xmas eve some lowlifes had ripped an old guy off and left his house in a right state he had no heating and the db swap was lethal, we sorted all the wiring out and heating free of charge and got him sorted for christmas, The look on his face when it was done was worth every bit of it.

Give me a shout if you need the help and let's see if we can't sort it out for the Guy and see if any other members are up for the challenge.

GMES, as you've shown time and again, that's an outstanding offer and show of generosity. I've no doubt some forum members would get involved in this, but it's not really about him having nothing and being a charity case. He lives in a very nice two-bed stone terrace house, and I can't comment on his financial situation but he strikes me as the sort that wouldn't be skint. I might have missed this point in my OP, but he's worried that spending money on a rewire might not be the best use of his money when he's in such ill health - for want of a nicer way of putting it, he's conscious of spending so much money today when he might not be here tomorrow.

There is of course the other side of the argument where he might have a good 10 years left, but this tripping RCD might be the death of him when he can't get his heating on, or when he falls down the stairs due to the house being pitch black.

Ultimately the decision is his (and his daughters) to make, but given the details in my OP, I guess what I'm asking is, in your professional opinion do you think replacing the single RCD board with a DP RCBO board is a viable cost effective solution to his problems. I guess to simplify it even further, would you be happy carrying out a board change when circuits have 2Mohm IR?

 

[GMES]

Just picking up on the last part of your reply mate I would say yes swapping the board out is at least a very good place to start. It has to be better than the situation he has at the moment, now on the subject of your IR readings while they are far from perfect they are technically greater than the required figure and therfore meet current regulations, now before I got bashed by anyone in a normal everyday situation we would all rewire the place but this chap in my opinion deserves a break.
One last comment on the matter of him being plunged into Darkness would it not make sense in addition to the new Board to also add some form of emergency lighting on the staircase and in high risk areas of the house.
Just food for thought mate.

 

[Octopus]

If the client is experiencing occasional nuisance tripping with a cu with a single RCD, an rcbo board would be my suggestion.

How many circuits?

 

[hightower]

One last comment on the matter of him being plunged into Darkness would it not make sense in addition to the new Board to also add some form of emergency lighting on the staircase and in high risk areas of the house.
Just food for thought mate.

Thanks GMES. That's more or less what I was thinking, that surely there's justification for doing the swap in this instance even given the low IR. As for the emergency lighting, I think that's a brilliant idea and will be mentioning it to his daughter tomorrow,

If the client is experiencing occasional nuisance tripping with a cu with a single RCD, an rcbo board would be my suggestion.

How many circuits?

Thanks Murdoch - there's six circuits total, 5 with low IR and the shower circuit with great IR.

 

[Octopus]

Thanks Murdoch - there's six circuits total/QUOTE]

So shopping carefully would get you a RCBO board for about £105 so that's a no brainer

 

[hightower]

So shopping carefully would get you a RCBO board for about £105 so that's a no brainer

Double pole? I think it would be prudent in this case to fit double pole

 

[Bobster]

Double pole? I think it would be prudent in this case to fit double pole

SBS double pole would be ideal in this situation. If a circuit trips it will at least clear the N>E fault if there is one. Keeps every circuit completely isolated from the others. An from what I've seen they are around £12 an RCBO, not going to break the bank.

 

[hightower]

Thanks everyone. From the start I was thinking of replacing the board which is the reason I posted up in the first place - I didn't want to suggest that to the guy and then have a forum full saying it's a bodge. The fact I got the answer I was looking for is great news for this guy. I'll be suggesting a board change as well as talking about emergency lights. Thanks to all who contributed.

 

[Dave OCD]

Hightower this is probably a silly question but did you do the I.R testing with the neutrals disconnected within the board ? It just seems odd that 5 circuits have very similar relatively low results ?

 

[hightower]

Hightower this is probably a silly question but did you do the I.R testing with the neutrals disconnected within the board ? It just seems odd that 5 circuits have very similar relatively low results ?

Not a daft question at all and I see what you're saying. I didn't, so it's probably a neutral earth fault on one circuit in particular. Although I did do line neutral individually and it got the same results. I've had a drink, sorry, i don't even think I'm making sense in my own head

 

[Dave OCD]

Give it a try mate and I bet one circuit will be the main culprit.

 

[hightower]

Yeah, I will do. I will be updating the thread when they make a decision

 

[Midwest]

Not withstanding the low IR results, I guess the culprit for the RCD tripping could be a plugged in appliance, as you mentioned your clamp meter readings suddenly momentarily peaking.

Whilst spreading the circuits across RCBO's, the culprit could still be lurking. Just clamped my supply, and it was chugging along at 6ma, until the fridge freeze kicked in and it went up to 16mA. Dunno what other appliances the old chaps got?

Something to consider, what they might think after you've installed a new CU, and the socket RCBO still trips. Just saying.

 

[hightower]

I think before I do I'm going to go back and disconnect the neutrals and ir test again. Just to be sure if it's the general wiring age or a particular circuit

 

[HappyHippyDad]

I'm a bit confused why a rewire is being taked about with results of 2-3Mohms? I realise that HT will probably find that the 2-3Mohms is only on one circuit after disconnecting the neutrals but even if they were on most circuits this is still >2'000'000 ohms of resistance to earth which does not even require investigation.

Sorry HT, I've read it a little slower this time and I see that you were probably realting the re-wire more to the contribution to earth leakage for each circuit.

I think I would do more testing and investigations and I bet you find a circuit or appliance that is causing more earth leakage than the others, you could then recitify that and give the install a few more years until the chap has passed on.

I find our approach to death pretty barbaric, we keep someone alive with tubes in every orifice and force feed them whilst they are in pain. A massive rewire seems a bit akin to this, causing huge disruption when it may well not be necessary. Fault find further and then a board change with RCBO's if really necessary.

 

[hightower]

I'm a bit confused why a rewire is being taked about with results of 2-3Mohms? I realise that HT will probably find that the 2-3Mohms is only on one circuit after disconnecting the neutrals but even if they were on most circuits this is still >2'000'000 ohms of resistance to earth which does not even require investigation.

Sorry HT, I've read it a little slower this time and I see that you were probably realting the re-wire more to the contribution to earth leakage for each circuit.

I think I would do more testing and investigations and I bet you find a circuit or appliance that is causing more earth leakage than the others, you could then recitify that and give the install a few more years until the chap has passed on.

I find our approach to death pretty barbaric, we keep someone alive with tubes in every orifice and force feed them whilst they are in pain. A massive rewire seems a bit akin to this, causing huge disruption when it may well not be necessary. Fault find further and then a board change with RCBO's if really necessary.

To be fair, if you got called to a house and you were getting 2-3MOhms on each circuit you would probably suggest a rewire. 2Mohm doesn't REQUIRE investigation, but I wouldn't be happy working on an install ordinarily with readings as low as that. Yep, it might be fine for the now, but how long does that cable have left?

As I've said, I think in this instance I'd be happy to replace the board in a bid to get a few more years out of the wiring - but that wouldn't be my go to in every situation. I've taken on board what people have said about splitting the neutrals, and I've yet to get back for that. However, I did clamp the earth and turn each circuit on one at a time - and each circuit was individually contributing to earth leakage. Added to the fact this guy claims the problem has gotten progressively worse over 6 years tells me there's a general breakdown of insulation.

 

[Deleted member 26818]

Thought it was said, that the earth leakage increased as each circuit was energised?

 

[Dave OCD]

To be fair, if you got called to a house and you were getting 2-3MOhms on each circuit you would probably suggest a rewire. 2Mohm doesn't REQUIRE investigation, but I wouldn't be happy working on an install ordinarily with readings as low as that. Yep, it might be fine for the now, but how long does that cable have left?

As I've said, I think in this instance I'd be happy to replace the board in a bid to get a few more years out of the wiring - but that wouldn't be my go to in every situation. I've taken on board what people have said about splitting the neutrals, and I've yet to get back for that. However, I did clamp the earth and turn each circuit on one at a time - and each circuit was individually contributing to earth leakage. Added to the fact this guy claims the problem has gotten progressively worse over 6 years tells me there's a general breakdown of insulation.

I'm sorry if you've already mentioned it HT but are the cables as far as you know all PVC insulated ? Any sign of rubber anywhere and it would definitely want rewiring with the age that would be now.

 

[hightower]

Thought it was said, that the earth leakage increased as each circuit was energised?

It was said, hence each circuit must be individually contributing to the overall leakage.

I'm sorry if you've already mentioned it HT but are the cables as far as you know all PVC insulated ? Any sign of rubber anywhere and it would definitely want rewiring with the age that would be now.

I've not seen rubber, but I haven't done a massive amount of digging about