Court case

[Singer]

Hi everyone,
Just been reading about a court case against two electricians which is being heard at Wolverhampton Crown Court at the moment concerning the electrocution of a 22 year old mother in 2007.
You would think that a professional prosecution barrister would have done some thorough research on the subject to compile a case against the 2 electricians in the dock, and would more than likely have received professional advice from experts within the industry.
I am therefore confused to read
"He told the jury that when a working circuit is insulation tested it should show a meter reading of 200 mega-ohms, and anything under that reading should have alerted an electrician to a problem.Of the faulty circuit, he said: “A resistance test would have produced a reading of 0.02 mega-ohms, some 10,000 times less than the 200 mega-ohms figure.”
Nevertheless, he said a reading of 200 was recorded by xxxxxxx. Prosecution barrister also said that, on the same form, a reading of 200 was given by xxxxxxx for a circuit that did not exist in the flat."

I am at a loss to understand where he gets the figure of 200 mega-ohms from.

My understanding is the Health & Safety Executive quotes anything under 2 m ohms should raise alarm and be further investigated.
Your thoughts please

 

[NickD]

It has been reported as being a new install. A newly installed circuit IR tested on its own, especially something simple like a short cooker or immersion radial, can be expected to produce an out of upper range meter reading, which could be >200Mohm (my MFT out of range is >1000Mohm on the 500V test range).

Resistance test would have produced a reading of 0.02Mohm between what and what, Mr Barrister? Line and CPC? It has been reported that the line was shorted to metal studwork by a screw which had nicked the line conductor. If that is the case and the studwork was bonded to earth and the IR test was carried out with the CPC connected to the means of earthing, you would expect the test to show a dead short (possibly an out of lower range reading, which could be 0.02Mohm I suppose).

This is an extremely good example of why it's important to IR test with CPC connected to means of earthing. Test it with the CPC connected to nothing and (unless it has a chance connection to a parallel path to earth somewhere), it'll pass with flying colours.

 

[Marvo]

Have you got a link to the news article you were reading?

 

[Singer]

Test may have found electrical fault which killed mother, court told « Express & Star

 

[Geoffsd]

Where have you been?

http://www.electriciansforums.co.uk/electrical-forum-general-electrical-forum/89056-electrician-qs-trial-death-woman.html

 

[NickD]

One assumes the studwork cannot have been bonded to the MET, as the screw taking it live did not not trip the circuit 3 fuse. In which case the circuit 3 IR test L-E would read whatever the path was between the studwork and earth on the day of the test - if carried out with the CPC connected to means of earthing.

I believe the particular emphasis on IR testing with CPC connected to means of earthing is relatively recent, can anyone confirm/deny?

 

[jimmymac]

Hi everyone,
Just been reading about a court case against two electricians which is being heard at Wolverhampton Crown Court at the moment concerning the electrocution of a 22 year old mother in 2007.
You would think that a professional prosecution barrister would have done some thorough research on the subject to compile a case against the 2 electricians in the dock, and would more than likely have received professional advice from experts within the industry.
I am therefore confused to read
"He told the jury that when a working circuit is insulation tested it should show a meter reading of 200 mega-ohms, and anything under that reading should have alerted an electrician to a problem.Of the faulty circuit, he said: “A resistance test would have produced a reading of 0.02 mega-ohms, some 10,000 times less than the 200 mega-ohms figure.”
Nevertheless, he said a reading of 200 was recorded by xxxxxxx. Prosecution barrister also said that, on the same form, a reading of 200 was given by xxxxxxx for a circuit that did not exist in the flat."

I am at a loss to understand where he gets the figure of 200 mega-ohms from.

My understanding is the Health & Safety Executive quotes anything under 2 m ohms should raise alarm and be further investigated.
Your thoughts please

That could easily be a printing error or an error on the court reporters side. If not, the defence should jump on that

 

[Marvo]

Where have you been?...

Mostly in sub-Saharan Africa.

I just wanted to make sure that the details being discussed were on public record

 

[spark 68]

One assumes the studwork cannot have been bonded to the MET, as the screw taking it live did not not trip the circuit 3 fuse. In which case the circuit 3 IR test L-E would read whatever the path was between the studwork and earth on the day of the test - if carried out with the CPC connected to means of earthing.

I believe the particular emphasis on IR testing with CPC connected to means of earthing is relatively recent, can anyone confirm/deny?

This was installed to the 16th edition Nick, before 2007 prior to the 17th (2008), in the 16th there was no need to bond or earth metallic parts (excluding screws, nails, fixings etc.) in walls until the 17th came out.

In fact it was more than likely that that incident itself lead to the reg being put in the 17th in the first place, or had a large bearing on it

 

[Singer]

So now the Qualifying Supervisor has been found guilty of breaching Health & Safety Regs having never set foot on the premises in question.
What else could he have done?

Electrician ?signed off? job that left young West Bromwich mother dead « Express & Star

 

[NickD]

Not signed whatever it was that he signed. It depends what it was that he actually signed. Do we guess it was the I&T box on a multi signature EIC?

 

[snowhead]

What else could he have done?

Made sure the "Electrician" he was countersigning was exactly that.
According to the article in the Mail he wasn't Qualified.

Ps think they meant Electricians Mate not mate of Electrician;

However, in a police interview, Mr Tomkins described himself as 'a mate of an electrician' and 'was not qualified as an inspector', Wolverhampton Crown Court heard.

Read more: Emma Shaw electrocuted 'because electrician was UNQUALIFIED' | Mail Online

​

 

[Singer]

Made sure the "Electrician" he was countersigning was exactly that.

​

Not sure if that is one of the responsibilities of a QS.

 

[Zebra Stripe]

This was installed to the 16th edition Nick, before 2007 prior to the 17th (2008), in the 16th there was no need to bond or earth metallic parts (excluding screws, nails, fixings etc.) in walls until the 17th came out.

In fact it was more than likely that that incident itself lead to the reg being put in the 17th in the first place, or had a large bearing on it

I feel a little uncomfortable talking about this for obvious reasons, but hey when has it been a requirement to bond metal work which is not extraneous whether under 16th or 17th ???

 

[telectrix]

the metal studding does not need to be earthed/bonded now. 522 6.103 applies .

 

[spark 68]

I feel a little uncomfortable talking about this for obvious reasons, but hey when has it been a requirement to bond metal work which is not extraneous whether under 16th or 17th ???

You are of course correct Zebra,

It was this bit that I meant that was specifically added to the 17th edition wrt metallic stud work, and was actually more to do with RCD protection and other protective measures (see 522.6.8) rather than bonding per se.

In the 16th there was no requirement to add RCD protection to anything other than S/Os for use outdoors and showers (unless TT).

The reason that reg was specifically added was (apart from the on going court case), a) the metal studding would not be exposed in the finished building, and b) unlikely to test as extraneous either.

Adding an RCD may have saved the poor young ladies life.

Bonding may, or may not be practicable if the metallic stud work is in multiple parts, plus of course how would the connections remain accessible for T&I.

I made a mistake in my original reply to Nick by referring to his use of the word bonding in his original post, it was very late when I replied to this post originally. lol

 

[Geordie Spark]

the metal studding does not need to be earthed/bonded now. 522 6.103 applies .

Maybe after this case that will all change?

 

[Zebra Stripe]

Ive tried to reply to this about 4 times now, maybe my usless piece of carp Iphone , but its like pulling teeth… i give in… cool spark 68 i understand what you mean

 

[NickD]

Maybe after this case that will all change?

Maybe it needs to be like supplementary bonding in bathrooms - required unless all circuits in the location (or in this case passing through the location) are RCD protected, all extraneous are protectively bonded, ADS disco times are met.

 

[Marvo]

TBH it's probably a moot discussion, I see RCBO's being standard fitment for every circuit a couple of years from now.