I'm totally baffled !!??

[Torturedsole]

Hi All

New here !

So this has me stumped .

I'm currently renting my house privately and i asked permission to have smart meters installed as i currently have really old analogue ones . When the chap , who was from a subby of Scottish power , Turned up he plugged his socket tester ( cant remember the brand ) and he got the weird reading as i have gotten in the attached pictures ( the fluke one is my own , i have also tried 2 other ones ).
As you can see the red LED lights up even when the switch is off on the socket , but it isn't always present , some times its dimmer , sometimes its not there at all. For instance when i was taking these photos , at first it didn't light up , then after like 30 seconds or so it came on .
The installation has passed its inspection , i have the cert , and i asked the landlord to send someone to take a look to be sure and they said they hadn't see it before . Ive searched the net and i cant find any reason for this ??

Trouble is the subbie wont come out to fit the smart meters as they seem to think its massively dangerous ??

Any ideas ???

TIA !

 

[timhoward]

Is it like that in ALL sockets?
If the cooker switch has a socket on it pls try that one too (it will be a different circuit)
A picture of consumer unit, meter area and cutout (where supplier fuse is) might help too.

 

[snowhead]

So the Scottish Power subby thinks it's massively dangerous, pressumably did not carry out any other tests and walked away leaving the installation Live without a known explanation for the apparent fault??

It may not be dangerous but untill proven otherwise it should not have been left live.

And did the Landlord's Electrician arrive pretty quick and come to the same conclusion or have they not arrived yet?

 

[Torturedsole]

So the Scottish Power subby thinks it's massively dangerous, pressumably did not carry out any other tests and walked away leaving the installation Live without a known explanation for the apparent fault??

It may not be dangerous but until proven otherwise it should not have been left live.

And did the Landlord's Electrician arrive pretty quick and come to the same conclusion or have they not arrived yet?

He has been , chucked his meters on and said he cant find out why .
Also to add i think the guys the subby sends aren't spark's they just plug in the socket tester to check , i doubt they know how to use any other meters .

Ive got this off the recent test report for the house " Circuits are satisfactory . Problem with earth fault test reading too high on TT system . Exposed conductors on RCD enclosure . Cooker MCB 40a too high for a 6mm cable , RCD doesn't trip a 5 x fault current " And as a whole it received a satisfactory

 

[Torturedsole]

Is it like that in ALL sockets?
If the cooker switch has a socket on it pls try that one too (it will be a different circuit)
A picture of consumer unit, meter area and cutout (where supplier fuse is) might help too.

Yes all sockets , up and downstairs. (diff circuits)
No cooker socket

 

[littlespark]

He has been , chucked his meters on and said he cant find out why .
Also to add i think the guys the subby sends aren't spark's they just plug in the socket tester to check , i doubt they know how to use any other meters .

Ive got this off the recent test report for the house " Circuits are satisfactory . Problem with earth fault test reading too high on TT system . Exposed conductors on RCD enclosure . Cooker MCB 40a too high for a 6mm cable , RCD doesn't trip a 5 x fault current " And as a whole it received a satisfactory

Sorry… “exposed conductors….” And he gave it a satisfactory?

I take it he means there’s excess copper showing at the terminals, but can’t be touched because it’s inside an enclosure… so not actually “exposed”

40A is fine for a 6mm cable, generally.

And RCD not tripping is a C2. Potentially dangerous.


Now, the plug in tester…
I can’t quite see what the pattern of lights means, but green lights normally means good… Red light bad.

If the red light indicates a neutral/ earth fault, then that will still be there with the switch off at the socket, as the switch only breaks the live, not neutral conductor. (Some are double pole, but obviously not this one)

 

[pc1966]

He has been , chucked his meters on and said he cant find out why .

Looking at the tester photo (other site, sharper picture) I think the red LED shows N-E voltage. Normally that is quite low as N is linked to E somewhere (just where defines the TN-S / TN-C-S / TT systems). But in your case it clearly is not so either N is at an elevated voltage w.r.t. true Earth, or your E is somehow "livelier" than it should be.

Also to add i think the guys the subby sends aren't spark's they just plug in the socket tester to check , i doubt they know how to use any other meters .

Probably...

Ive got this off the recent test report for the house " Circuits are satisfactory . Problem with earth fault test reading too high on TT system . Exposed conductors on RCD enclosure . Cooker MCB 40a too high for a 6mm cable , RCD doesn't trip a 5 x fault current " And as a whole it received a satisfactory

Well it should only get satisfactory if those issues have now been fixed!

The very first point sound suspicious to me as a VERY poor / missing earth rod could result in the system CPC ("earth" conductor) being at enough of a voltage w.r.t. neutral to light an LED.

The RCD failing to trip is also worrying if it has not been replaced or another reason found and fixed. Personally you need to get back to landlord and get someone out who does find the reason for the high N-E voltage. At the very least measure the earth rod Ra value to confirm it is adequately low, and measure the N-E voltage to see if it is sane (handful of volts typically, probably no more than 10-15V if voltage drop is being met I guess).

 

[timhoward]

I had a hunch this was TT.
A non working RCD is a very big deal on TT systems and even more so in your case if the impedance is too high even for TT.
There is no guarantee a fault will disconnect the supply at the moment and this is a fire risk.
In short the installation needs looking at again prettty urgently by someone competent.
What area in Wales btw?

 

[Torturedsole]

Sorry… “exposed conductors….” And he gave it a satisfactory?

I take it he means there’s excess copper showing at the terminals, but can’t be touched because it’s inside an enclosure… so not actually “exposed”

40A is fine for a 6mm cable, generally.

And RCD not tripping is a C2. Potentially dangerous.


Now, the plug in tester…
I can’t quite see what the pattern of lights means, but green lights normally means good… Red light bad.

If the red light indicates a neutral/ earth fault, then that will still be there with the switch off at the socket, as the switch only breaks the live, not neutral conductor. (Some are double pole, but obviously not this one)

Yea , on my socket tester , there isnt actually a pic that show all 3 leds lit up , generally the 2 green is all good , then its either of the greens with a red indication reversed live/neutral . Which is whats throwing me , no idea what all 3 means

 

[Torturedsole]

I had a hunch this was TT.
A non working RCD is a very big deal on TT systems and even more so in your case if the impedance is too high even for TT.
There is no guarantee a fault will disconnect the supply at the moment and this is a fire risk.
In short the installation needs looking at again prettty urgently by someone competent.
What area in Wales btw?

I'm in Abergavenny .

Problem is hes signed it off as satisfactory , so the landlord is likely to laugh me off . Only way round it is to actually catch fire then i can say something

 

[timhoward]

Yea , on my socket tester , there isnt actually a pic that show all 3 leds lit up , generally the 2 green is all good , then its either of the greens with a red indication reversed live/neutral . Which is whats throwing me , no idea what all 3 means

My long range complete guess - a Neutral Earth fault in fixed wiring or a connected load (which would normally trip your RCD), and loose connection on earth rod.
That would lead to a basic tester thinking earth has too much voltage to be earth and cause the LED to glow.

 

[Torturedsole]

The test certs if that helps ?

 

[snowhead]

Did the "Smart Meter" person leave any paperwork saying it's "massively dangerous" or anything saying why they wouldn't fit the meter?
I'd be amazed if someone left paperwork saying the installation is too dangerous, but also left it live.

He has been , chucked his meters on and said he cant find out why .

And what does he propose doing about it?
Any paperwork?

 

[Torturedsole]

Did the "Smart Meter" person leave any paperwork saying it's "massively dangerous" or anything saying why they wouldn't fit the meter?
I'd be amazed if someone left paperwork saying the installation is too dangerous, but also left it live.


And what does he propose doing about it?
Any paperwork?

No to both.

the smart meter guy just rang his supervisor and told him , who in turn told him to walk away
And the landlords sparky came like 2 days later and he tightened a few terminations up and the led went out , so he thinks he fixed it , but like i said on the origional post , the leds dont stay one , they are random

 

[littlespark]

Normally, there is no voltage neutral to earth… so it’s possibly not an option on these testers.

Looks like VIR tails between cutout and meter which could do with being replaced, but that should be done if the meter is changed.

The test certificate doesn’t have a number for “points served”
How difficult is it to count light bulbs?

 

[OnlQQker]

You wouldn't happen to have an outside light tapped into that circuit by any chance?

 

[timhoward]

It looks as though this is a report completed after some of the concerns were addressed.
According to the report and pictures the cooker is now on a B32, there is no longer an RCD enclosure, and the (presumably) two RCD's are both operating within required times, assuming the 333 was a typo and should be 33 like it's neighbours.

The main thing that jumps out now, as the OP already mentioned is the earth electrode impedance is well above what I'd be happy with, mitigated by the fact that fault protection is being provided by the RCDs.

 

[Torturedsole]

You wouldn't happen to have an outside light tapped into that circuit by any chance?

There is an outside light , which may be tapped into it

 

[goasis]

The test certificate doesn’t have a number for “points served”
How difficult is it to count light bulbs

The tester apparently didn't even know what voltage he/she was doing the IR testing at, or any mention of how they've managed to get RCD test results when there's no RCD mentioned, and presumably don't know where to find max zs values in bs7671 as they are N/A as well.

 

[Dave OCD]

And all the circuit Zs readings are waaay below Ze value ?! Were these measured with all the bonding connected ?

 

[goasis]

And all the circuit Zs readings are waaay below Ze value ?! Were these measured with all the bonding connected ?

That's to be expected though isn't it?

 

[littlespark]

The tester apparently didn't even know what voltage he/she was doing the IR testing at, or any mention of how they've managed to get RCD test results when there's no RCD mentioned, and presumably don't know where to find max zs values in bs7671 as they are N/A as well.

I had to look at that… the BS number suggests MCB, but there’s RCD trip times. Wasn’t until I noticed the times were all the same that I realised.
Must be a dual rcd board,

 

[goasis]

I had to look at that… the BS number suggests MCB, but there’s RCD trip times. Wasn’t until I noticed the times were all the same that I realised.
Must be a dual rcd board,

So why aren't they listed at the top of the certificate then? The cert is a load of crap.

I think I over worry about getting things wrong/ missing something and look back at some things I've done or not understood correctly in the past and cringe, but then you see something like this, this is just poor.

 

[timhoward]

So why aren't they listed at the top of the certificate then?

I certainly would do this for clarity, and I know what you mean, but is there an absolute requirement to list the two RCD's on their own line?
Ultimately we are listing final circuits and what is protecting each one.

 

[goasis]

I certainly would do this for clarity, and I know what you mean, but is there an absolute requirement to list the two RCD's on their own line?
Ultimately we are listing final circuits and what is protecting each one.

I was thinking the " characteristics of this db" section, "associated RCD's". Would you not use that?

 

[timhoward]

I was thinking the " characteristics of this db" section, "associated RCD's". Would you not use that?

No, as that is "Complete only if not connected directly to the origin", i.e. a sub main
Napit's certifcates could be better worded in that part.

 

[goasis]

No, as that is "Complete only if not connected directly to the origin", i.e. a sub main
Napit's certifcates could be better worded in that part.

Oh yeah, see that now. Good point.

 

[littlespark]

There’s enough lines to add in a couple of rcd’s.
That gives a chance to note their BS numbers, size etc… which could be wrong when you total the load that it’s expected to carry.
N/A or leave blank a lot of the other columns, but put “for circuits 1-5” or whatever it is.
Looks understandable when you’ve got the sheet, and the board in front of you.

Just lazy not to

 

[telectrix]

Normally, there is no voltage neutral to earth… so it’s possibly not an option on these testers.

Looks like VIR tails between cutout and meter which could do with being replaced, but that should be done if the meter is changed.

The test certificate doesn’t have a number for “points served”
How difficult is it to count light bulbs?

all depends on how deep you planted them.

 

[Deleted account]

Split board on a TT system. I hope there is an up front time delayed RCD.

@Torturedsole , any chance of photo of CU with lid up.

 

[Dave OCD]

That's to be expected though isn't it?

I must be having a thick moment ?! Thought Zs was Ze + R1&R2 ?

 

[goasis]

I must be having a thick moment ?! Thought Zs was Ze + R1&R2 ?

Interesting, by calculation yes, but would you take a Zs measurement without bonding connected?

 

[Julie.]

The tester apparently didn't even know what voltage he/she was doing the IR testing at, or any mention of how they've managed to get RCD test results when there's no RCD mentioned, and presumably don't know where to find max zs values in bs7671 as they are N/A as well.

Zs isn't really applicable with a TT system as the RCD is providing fault protection, not the mcbs - they would never trip with 315 ohm earth rod.

 

[goasis]

Zs isn't really applicable with a TT system as the RCD is providing fault protection, not the mcbs - they would never trip with 315 ohm earth rod.

Yeah I know... maybe I was over reacting. No excuse for the NA in the IR test voltage tho eh?!!

 

[Julie.]

Yeah I know... maybe I was over reacting. No excuse for the NA in the IR test voltage tho eh?!!

Nope, pure muppetry that one!

 

[Torturedsole]

Yea i can take a photo of the cb.

But we have seemed to of gone wayyyyy off topic here

 

[Julie.]

OK, let's try to explain.

A socket tester basically measures three voltages simultaneously.

The first (LH) green LED indicates that there is some voltage between line and neutral - which there should be in correct operation.

The second (Centre) green LED indicates that there is some voltage between line and earth - which there should be in correct operation.

The third (RH) RED LED indicates that there is some voltage between neutral and earth - which normally there should NOT be in correct operation (at least not too much voltage).

How much voltage? - well that depends on the tester, some containing electronics will indicate at lower voltages than less fancy ones, but typically it may be 50v

So the tester is basically saying there is at least 50v (ish) between L - N -- OK, L - E -- OK, and N - E -- NOT OK.

why are you getting a reasonable level of voltage between N & E - Well that's not too unrealistic with a TT system, the neutral and earth can differ by some amount, these quick testers are not great on TT systems, some are OK as they may trigger at 50v, which would indicate a genuine issue, others may operate at a much lower voltage.

You need firstly to measure the voltage L - E using a high impedance meter (like a multimeter), then via a lower impedance meter such as a MFT (multi function tester), you would need to bring in a proper electrician for this.

Does this actually represent a danger - well it depends on the results - if the voltage measures the same, then you have a genuine voltage, and depending upon the value it is OK, or not.

If the voltage changes between the two measurements, then you have a poor/missing connection, likely in the CPC (earth) which is an issue.

Edit:

Should really have added, that some of the more fancy socket testers actually try to measure the Zs and if greater than a certain value ( typically 1.5 or 2.5 ohm) then the electronics flags it as a fault, and since your Zs are around 315 ohm (TT) then a fancy one would do this.

 

[Julie.]

Also, and not relating to the "issue" , that tester you are using has been recalled for safety issues.

If you contact fluke they will replace it.

Fluke SM100, SM200 and SM300 Electrical Socket Testers Voluntary Recall

Fluke Corporation has identified a safety issue concerning the Fluke SM100, SM200 and SM300 Electrical Socket Testers. As a precautionary measure, Fluke has decided to voluntarily recall all of these products and provide affected customers with free replacement products.

www.fluke.com

 

[nicebutdim]

Also, and not relating to the "issue" , that tester you are using has been recalled for safety issues.

If you contact fluke they will replace it.

Fluke SM100, SM200 and SM300 Electrical Socket Testers Voluntary Recall

Fluke Corporation has identified a safety issue concerning the Fluke SM100, SM200 and SM300 Electrical Socket Testers. As a precautionary measure, Fluke has decided to voluntarily recall all of these products and provide affected customers with free replacement products.

www.fluke.com

They won't directly replace it, but will send a T90 voltage tester.

 

[Julie.]

They won't directly replace it, but will send a T90 voltage tester.

Yeah, there are a couple of options, neither are that good tbh

The issue is really esoteric, basically if the only connection is one 230v live (neutral or line), then you could get circ 10mA if you touched the earth (when the cpc is missing), so I would be happy to use them in any case.

In saying that, I don't have a socket tester, I fid my mft is perfectly capable of testing socket outlets.

 

[nicebutdim]

Yeah, there are a couple of options, neither are that good tbh

The issue is really esoteric, basically if the only connection is one 230v live (neutral or line), then you could get circ 10mA if you touched the earth (when the cpc is missing), so I would be happy to use them in any case.

In saying that, I don't have a socket tester, I fid my mft is perfectly capable of testing socket outlets.

From the wording in Fluke's recall, I suspect someone got a tingle and fell off their ladder.