Insulation resistance test issue

[naylorpd]

Back in 2013 I had a Domestic Electrical Installation Condition Report done on my rented property - nothing horribly major but one thing I didn't understand...

I had a C3 code for "0 ohms readings for I.R test for sockets & lighting (unable to remove all loads sockets, lighting had electronic dimmers)"

I didn't do anything about this at the time, but 5 years on I'm thinking that cables don't improve with age so perhaps I should get the insulation testing done this time.

So...
1) Yes I have some electronic dimmers, so how do I overcome this? Do they need to be taken off to do the IR testing? And do I need to put ordinary switches back on temporarily, or can I just unscrew the live cable, do the test and put the switches back?
2) I don't understand how sockets would have been a problem, surely it's easy enough to just unplug everything. Was the tester just being lazy, or is there another problem that isn't really being explained?

Thanks
Phil

 

[Silly Sausage]

I would say the N-E IR was probably done with the main switch on !

How much were you charged for this "report"?

Maybe they have TNC installations in Azerbaijan?

 

[johnduffell]

Im not after the limitations or i woukd be asking for page 1. Im after the deviations that he has found on his EICR.

Ok but a deviation is a design decision made that doesn't comply with the regs but provides an equivalent level of safety to that which would comply.
If they were listed on the eicr, it would only be a comment referencing the eic. If a non compliance was found it would be given a classification code depending on what kind of danger it posed.

 

[naylorpd]

I think this time round I'll be there when it's done. Sounds like I need to be!

S'funny, 20-30 years ago when you hired an expert you just left them to get on with it, nowadays you need to have a much higher degree of understanding to even define the job that needs to be done. But that's getting a bit philosophical...

This is for my house in UK, but where I (mainly) live in Azerbaijan all tradesmen are called "meister" - but most of the time I know more about how to do the job than they do.

 

[Silly Sausage]

S'funny, 20-30 years ago when you hired an expert you just left them to get on with it,

Sadly true.
Read these forums and you'll find that there is a lot of discontent within the industry!

 

[naylorpd]

Maybe they have TNC installations in Azerbaijan?

This is my house in Reading!

In Azerbaijan many, even most, houses are wired without earth cables at all. I have a 3 phase supply with 4x16mm aluminium cores. I put two large earth rods in the garden. The house is wired with T&E and CU imported from the UK, apart from first fix I did most of it myself, including learning to strip 4x35mm SWA.

But over in the thread where you post photos of bad installations I added some pics of the usual standards here.

 

[Ian1981]

A L—N IR test is not a limitation if not carried out as it’s not an essential test for a eicr and the actual IR testing should be carried out between live conductors together and earth

 

[Risteard]

and then test L to N at 250V

I don't ever test between live conductors during a periodic inspection. It's not remotely feasible. It is always an agreed limitation of mine. (If they declined the agreed limitation then it would have a very large upward effect on the quoted price.)

 

[M-Ty]

Which was the 0MOhms recorded? L-N, L-E or N-E?

It was given as 0 ohms, not 0 megohms, nor "less than 1 megohm", nor even 0.1 milliohm.
It was obviously untrue, as the installation hadn't gone bang!

 

[Lucien Nunes]

The IR columns are headed MΩ, so a reading of '0' strictly means 'less than 500kΩ to one significant figure' but I don't think whoever wrote that thing understood such subtleties. Since an L-N reading of '0MΩ' could range from 500kΩ (non compliant but might be relatively safe) to 100Ω (probably on fire) to 1Ω (can't close the MCB) it's obviously not a helpful result to give and a bit more work is required during testing to find out what the actual resistance is.

And then there's the likely numpty-factor behind the N-E readings. I bet there's one N-E fault, the tests were done with all the N's still connected, and the circuits reading '0MΩ' for L-E still had load on so the line could see through to the neutral fault.

 

[freddo]

Was 6.0mm T+E ever made with a 1.5mm CPC?

 

[Dave OCD]

I don't think so,always 2.5mm cpc. And in the old imperial stranded equivalent it was almost certainly bigger.