Domestic Electrical Inspection Query..

[A100man]

Here's one for you..

Mate (honest!) has a rental property that failed an inspection recently - a few easy fixes but also 'Low IR reading on N-E connection at CU'

Now the test sheet shows individual IR readings (all > 999 MOhms) for L-L and L-E but there is no entry column for N-E readings, just this statement.. marked with a C2

Consequence £85 p/h plus VAT to investigate..

My question is whether that test is even valid a 'global N-E insulation resistance check? What if there was something plugged into a socket can that skew readings?

My gut feeling is this is an open ended hunt for money. Thoughts?
____________________
Now: A100, GT250A, XJ598, FZ750

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600

[Islander]

[A100man]

[Islander]

For sure some 'electricians' use EICRs as a quick way to make money and use some suspect results. Less than an hour is suspicious - although for a very small installation it may be appropriate. A full EICR really should take longer as they need to check R1+R2 (live/earth cable resistances - really important for meeting disconnect times etc), IR, Earthing of appliances, polarity and a bit more and that's a lot of work involving removing circuits from breakers etc. I'd expect half a day minimum.

Your friend could ask another known reputable electrician but it won't be free and may involve a recommendation of a retest. If that turns out to be the case then a report to the governing body (NICEIC or whoever) is a good idea.

Recommending board changes is a common one but should only be a C3 at best (recommendation only) unless there are clear dangers or imminent ones. There are good reasons for upgrading, say a fuse based board without RCD protection to a newer standard board but the original board would still comply with BS7671 and unless you're letting a property would not be a requirement.

I should state that although I have good knowledge of the procedures and regs, I'm not an electrician.

[A100man]

Yeah, property is a threes bed semi as far as I know.

Easy-fix faults were a missing blank on main CU, no RCD provision for sockets to be used outside and wrong rated RCD in garage CU (100mA instead of 30mA)..

The main CU already has some RCD I think (I need to check) so I do think the replacement of that is a con.

As you say a full test requires a fair number (half?) of the socket front for be removed an checked and lighting too afaik, on the face of it this inspection seems lacking.

I'm similar though not as well versed in the procedure I'd say - I did once complete a 17th edition course but that was some years ago..
____________________
Now: A100, GT250A, XJ598, FZ750

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600

[A100man]

Ok so now I'm a bit more enlightened but also confused by the report

https://www.youtube.com/watch?v=Ek1u2RjQffU

This video shows the IR test procedure at the CU first testing between lives (L to N in other words) then L&N combined to Earth, (no separate L-E or N-E) -since as I also noted there are only two columns in teh test sheet for IR test result..

But in my mates case all the L-N and LN -E tests are recorded as good passes (>999 MOhm) , so how can there be a N-E low reading
____________________
Now: A100, GT250A, XJ598, FZ750

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600

[Islander]

[A100man]

Ok Update..

Site visit by self reveals oldish MCB CU with auxiliary RCD units for the garage feed and cooker.. also already installed were some socket front RCD power breakers to serve the garden, ones which the erstwhile inspector didn't even spot!

The company is now back tracking I believe on the CU update requirement, and IMO brings into question the competence of tester.

There remains a question mark over the RCD requirement for the garage which is currently 100mA but the tester said should be 30mA, but could that be a retrospective value..?

Interestingly UK power networks had to renew the connection into the house as the main fuse blew in February and stated it was a TN-CS in theri paperwork left, but the tester identified it as TN-S..
____________________
Now: A100, GT250A, XJ598, FZ750

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600

[Islander]

[A100man]

[bugeye_bob]

The Ze would have been way lower on a TNCS system than a TT or TNS, even without a simple visual check as you did,

Any circuit not 50mm or below the surface, obviously surface conduit is different, needs a RCD anyway now,

What was the tripping time for the 100mA RCD circuit?

[A100man]

[Islander]

[A100man]

UPdate 2

The shysters have thrown the towel in.. back tracked completely and
are prepared to sign it off once some blanks have been fitted.

They are saying the presence of an RCD socket they didn't spot will have thrown out the N-E IR reading, but does that explain how they got
a good L - E reading? Possibly - I don't know enough about that.

The earthing bit wasn't relevant really just a point of interest but someone (UKPN or tester) has identified wrong,.. Ze noted as 0.6 for the record.

Many thanks for all the input - mate is happy and about 1k better off.
____________________
Now: A100, GT250A, XJ598, FZ750

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600

[MCN]

Lectric can be risky.
It can cause a fiyah.
Plate someone.
Cause a Power Outage which can effect more sensitive equipment.

Even the 12v shite.

We are more reliant on electricity in today's modern world so stuff has to be Pucka.
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.