Insulation resistance test at 250v

hedzball · 15-03-2022 12:52am #1

Lads a quick one here.

I'm doing a bit of work for a company installing disabled bathrooms and what I have noticed is when I go to do an insulation test i'm getting flat shorts across the board on my Fluke 1662. Now the houses generally are anywhere from early 1900s to 1960s at a push. Most of the clients are in their 80-90's. I have my main neutralising link out from the board but yet seem to have continuity between E/N . I have been just issuing hazard work forms. I am assuming someone robbed an earth for a neutral down the line etc.

According to ISO 10101 I should be getting a minimum of .5 ohm at 250v. This has happened in 4 houses in a row now and I'm kinda getting the idea that I'm missing something here??

Cheers

'hdz

kirk. · 15-03-2022 7:05am

Are you testing with appliances and lights in-circuit or just the fixed wiring ?

I'd probably pull the main neutral off the bar and make sure there's no reading between that and the MET

If appliances are in-circuit and there's no RCDs it could be them

Wiring is very old too by the sound of it

JL spark · 15-03-2022 9:14am

Would you not be better off pulling in a new circuit for the bathroom as standard, RCBO it an move on , or if installation is below power , walk away ,

kirk. · 15-03-2022 9:27am

https://www.boards.ie/discussion/comment/118786742#Comment_118786742

I assumed he'd have to , hardly be using the old work there ? 1960s wiring

I assume main bonding and earthing has to be in place when working on bathrooms ? Not too familiar

JL spark · 15-03-2022 9:32am

you would hope so , in a lot of cases it’s not , company’s don’t want to pay for it , all these houses need rewired , same with the EV points going into houses , from what I see , nothing is upgraded, that’s why our trade is in **** , sorry to the op , I didn’t mean to go on a rant , just boils my blood , race to the bottom

kirk. · 15-03-2022 9:36am

1960s(latest according to op) installation generally isn't safe . Although maybe there's been some upgrades

Bathroom work needs Main earthing and Bonding in place and as you say work with new final circuits and RCBOs

JL spark · 15-03-2022 9:38am

100% 👍

meercat · 15-03-2022 10:25am

Stopped doing bathrooms for this very reason. Too many issues on older installations. Nph had to be issued on every job and difficult to explain issues to older generations

every job required upgrading earthing and older installations had 10 mm mains

even by upgrading mains and earthing nph had to be issued for other problems in the house whilst testing and certifying

clients and bathroom company thought I was sticking the boot in as other electricians weren’t applying the same standards

JL spark · 15-03-2022 11:27am

https://www.boards.ie/discussion/comment/118786974#Comment_118786974

That’s the sad reality, too many shortcuts been done , and no one can do a thing about it ,

kirk. · 15-03-2022 12:20pm

There's paperwork being filled out here so there's a REC involved somewhere but problems are;

Tester doesn't know what his readings mean

Seems dubious that installations are safe for new bathroom work

And the main issue is that the work is proceeding and hazard work forms are being issued at the same time, so basically the contractor is passing the buck which is probably highly unsafe

meercat · 15-03-2022 12:46pm

https://www.boards.ie/discussion/comment/118787492#Comment_118787492

In fairness to the op,he does recognise and understand what his readings mean

he’s coming across issues on the existing installation

he’s obviously testing and certifying his own work correctly and diligently checking the existing installation whilst there

it is however important not to add additional loads to anyinstallation (showers,fan heaters,car chargers etc)if main cables cannot take the additional power and this should be checked before work commences.

kirk. · 15-03-2022 5:29pm

Yes, I may have phrased that badly

The OP is testing and recording the results fair enough and clearly knows what he's doing

I remember back in the day when the digital IR testers first showed up on the scene ,my inspector used to say to me that there was a lot to be said for an analogue reading

I know what he meant these days when i see the MFTs and myriad of readings and certifications. Sometimes the blindingly obvious and dangerous can be lost in the readings and paperwork

Seen it there with Boeing , when all the paperwork was analysed .Pilots had 10 seconds to make the right call in a certain situation or the 737max was doomed but it was overlooked

My 2C on this stuff anyhow

hedzball · 15-03-2022 11:01pm

https://www.boards.ie/discussion/comment/118789347#Comment_118789347

You're dead right you did phrase it badly but I try to overlook text and forums on a personal level.

"And the main issue is that the work is proceeding and hazard work forms are being issued at the same time, so basically the contractor is passing the buck which is probably highly unsafe".

It's not passing the buck by any means merely informing them of faults in their house. It is not my job to sort out every issue when I walk in the door. I wont get paid for that nor will they pay for it. I have had this issue highlighted with safe electric (J.C) and this is what I've been told to do. If I walk in the door and do everything to a level of 10101 I stand over the work I do and obviously deal with any obvious potential dangerous issues.. to a point..

I am a REC and I would hope to think I would know what I am at and can read my meters.... but I will admit houses aren't my primary focus hence my honest question of

"This has happened in 4 houses in a row now and I'm kinda getting the idea that I'm missing something here??"

FWIW new circuits yeah. Cert 3's being issued . 1 for tails change etc

Regards to bathroom bonding the whole bathroom is ripped out and all pipes are plastic and bonding is "Exposed conductive parts and extraneous conductive parts using supplementary protective equipotential bonding."

Regards to bonding you don't have to bond a tank if its a cert 3 but if theres a cert 1 you do (plus the sink if path to earth blah blah) I do it out of habit anyway.

Regards to every second fella doing it a different way I fully agree.. But you cant go into anyones house and tell them well what I did is up to spec but you need to do the rest of your house to be on par. Our job is merely to inform the client of issues and to wipe our hands of it.. Feck sake if you went through these houses with stevie wonder none of them would pass.

I had one today, 1950's bungalow.. That black rubber singles (I actually dont know the name of that stuff considering I was born 40 years later) Did my insulation test at 250V and I maxed out my meter so all good. I was merely curious to having 4 in a row if I was at something wrong or missing something...

On a separate note regarding testing of earth electrodes I see in the regs most readings come in "On average 0 to 20ohms" but I don't see a limit mentioned in the regs? I rang SE earlier and I got a figure of 1600ohms.. Most of my readings on the rods have been 200-300 .. I must admit none of these were new and I am just curious (again)

Cheers

'hdz

meercat · 16-03-2022 7:47am

https://www.boards.ie/discussion/comment/118791046#Comment_118791046

when you did that insulation test on a 1950s bungalow and you say it maxed out,what exactly do you mean.

i would expect an insulation resistance test on an installation that age to be quite low

JL spark · 16-03-2022 9:29am

are you saying ,If your working in a property with black rubber cables , you would cert the upgrade tails for your own work and just leave the old cables as they was ,

hedzball · 18-03-2022 1:08am

https://www.boards.ie/discussion/comment/118792102#Comment_118792102

No.

Antenna · 19-03-2022 11:49am

https://www.boards.ie/discussion/2058237413/insulation-resistance-test-at-250v

Regarding N and E touching somewhere, a high possibility is it is at lighting that requires an earth. Metallic light pendants might get pulled at during bulb changes , dusting/cleaning etc and this could eventually happen (insulation frayed/ pulled back on wires, and they come in contact). Obviously if L shorts to N or E they will know about it straight away (other lights also failing and it will have to be fixed), but not N to E (unless there is an RCD on lighting, which is only a recent requirement).

maestroamado · 19-03-2022 1:32pm

https://www.boards.ie/discussion/2058237413/insulation-resistance-test-at-250v

I expect you are being asked to sign off on the whole house as all connected to the board... the house clearly needs re-wiring...

Over the years i have seen earths and neutrals joined... i have also seen neutrals earthed where there was not an earth present...

It could be anywhere... good luck...

Insulation resistance test at 250v

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