IR reading of 3.4 mega ohms, upgrading CU help

[NellyManjaro]

Ok so I have been to a domestic property today, and carried out an EICR, couple of issues flagged up with regards to the usual no RCD protection bonding cables etc now its quite a big property and the customer has gone with my advice of RCBOs but one question. Most circuits tested fine but the kitchen ring has an IR reading of 3.4 mega ohms.... my question is as this is within the limits (greater than 1) is this ok to still upgrade and issue an EIC I have had a quick look behind all the sockets to check for anything obvious but nothing now i would usually recommend this is investigated further as a side note but the kitchen isn't the easiest place to do this and with an IR reading of 3.4 it is deemed ok and therefore no classification code is required just something I wonder if anyone else has come across before

Thanks

 

[HappyHippyDad]

That's 3,400,000 ohms of resistance to earth. Unless it's a brand new ring you've just put in its fine.

 

[Strima]

Nothing wrong with that reading, still well above the 30mA RCD trip threshold.

 

[pc1966]

Well it is a pass even if on the rather low side. Still with RCD protection it is a lot safer no matter what!

Was it tested with everything unplugged, or done by L+N to E as some things like washing machines too hard to move out to access sockets?

 

[Wilko]

As above I don't think I’d FI rate that value on an EICR but I would think about noting it and it could be a reason to retest more frequently.

Out of interest - how was the test done the result solid, or slowly improving?

 

[buzzlightyear]

What voltage did you put it at?

 

[telectrix]

could be a simple as a bit of water spillage that hasn't quire dried out. i'd not worry aboutit. BS7671 suggests that any reading under 2 Meg. should be investigated.

 

[pc1966]

As above! Probably a dirty or damp back-box causing it, though worst-case some fitter has nicked the cable with a screw or nail.

 

[telectrix]

As above! Probably a dirty or damp back-box causing it, though worst-case some fitter has nicked the cable with a screw or nail.

nicked is lucky. i.ve found a few cables with a rawlplug and screw sraight through 'em. bloody kitchen fitters.

 

[DefyG]

nicked is lucky. i.ve found a few cables with a rawlplug and screw sraight through 'em. bloody kitchen fitters.

Ditto - and the cables have been installed in ‘safe zones’!
[automerge]1602060093[/automerge]
3.4Meg as said before worthy of a note but otherwise compliant!

 

[Wilko]

As above! Probably a dirty or damp back-box causing it, though worst-case some fitter has nicked the cable with a screw or nail.

At my own house I found one of these when I replaced the kitchen bench top last year. The back rail on the wall had a screw in contact with the L of the RFC The cable was correctly in a zone and otherwise worked fine. But IR was about 10 meg if I recall correctly.

 

[pc1966]

If both L to E and N to E are similar and in the few meg region then I would guess damp/dirt. If N to E+MET is high but L to E+MET is low I would worry about cable damage by a screw or similar.

 

[DPG]

At my own house I found one of these when I replaced the kitchen bench top last year. The back rail on the wall had a screw in contact with the L of the RFC The cable was correctly in a zone and otherwise worked fine. But IR was about 10 meg if I recall correctly. View attachment 61247

Looks like the cable route is even marked on the wall !

 

[Wilko]

Looks like the cable route is even marked on the wall !

Ha - that was me - as I’d replaced that leg by the time of the pic and I wanted to make sure the Next Kev (me) didn’t repeat the same error

 

[Mike Johnson]

That is assuming the kitchen fitter could read English, I had a Polish worker on one of my sites that ripped up a piece of plywood that was shot fired to the concrete floor, it had big red lettering on it saying "Hole Under" he jemmied it up and walked forward and fell six stories down a service shaft, at the bottom was all the polystyrene that had been used to form the holes, the shaft was too small for him to turn during the fall and he just sustained a broken leg and hip, he was very lucky, but the accident report was interesting to fill out.

My most interesting accident report concluded "Too many knobs and not enough Knots"