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R

Richard Redman

Hi all, after some advise on bonding in a bathroom, ive fitted an electric shower, its RCD protected and ive bonded the water pipes. 2 of the walls in the bathroom are steel stud walls, another electrician says it doesnt need bonding as its on a RCD ? Help
 
Found this extract online
The case relates to the Death of 22 year old Emma Shaw who was the occupant with her 18 child month of a rented 1st floor flat in West Bromwich in December 2007.

The flat was one of new 42 flats that had electrical installation carried out by Anchor Building and Electrical services an NICEIC Approved Contractor in 2006.

The internal walls were constructed of "C" section metal studwork covered with plasterboard. A hall cupboard contained a pressurised water boiler above which was mounted a consumer unit supplied from a distribution circuit from a switch fuse in a an riser cupboard external to the flat. The means of earthing was TN-C-S. None of the circuits in the consumer unit were RCD protected. Circuit No. 3 supplied one of the immersion heaters in the boiler.

The electrical installation had been 1st fixed the plaster board fitted to the metal studding before the installation was 2nd fixed. Circuit 3 supplied a 20A double pole switch at high level which supplied a cable outlet at low level, this in turn supplied the water heater in flex.

The cable to the flex outlet was longer than it should be and when the plasterboard was installed the cable was trapped between the plasterboard and the stud-work. In addition a plasterboard screw passed through the cable clipping the Line and CPC conductors and in to the studwork.

The installation had been energised without any testing and the fault current had blown away part of the screw and CPC. This was verified by forensic examination at the HSE laboratories. This left a high resistance fault from the line conductor to the metal studwork.

18 months later the stat. on the water heater failed and the cylinder over pressurised and the safety valve operated and the safety valve operated and discharged in to a tun dish. The plastic waste pipe from the tun dish had parted because it was not glued and the water spilled on to the floor soaking the carpet. The water soaked under the foot of the wall and in to contact with the live studwork.

Miss Shaw was mopping up the water and had texted her partner to come home telling him the hall was flooded and the "electricity was sparking". he partner tetxed back to say to turn off the water stop cock sited in the same cupboard as the boiler.

Later she was found kneeling in the cupboard slumped forward and apparently lifeless. Subsequent examination and a Post Mortum determined that she was kneeling in the charged water and received a fatal shock when she touched the earthed stop valve.

West Midlands Police, the ambulance service and the fire service attended the scene. The police commenced an investigation for a suspicious death.

The police later arrested both the QS Hoult and Tomkins the electricians mate and they were interviewed under caution. Tomkins had signed an Electrical Installation Certificate as the Inspector. He admitted he was not qualified or competent to do so. He said he had been taken to the flat by the electrical site foreman and told to do ring continuity and loop impedance testing.He said when he got to the flat the installation was already energised. He did no other inspection and testing. He said that in the site hut they had sat around the table with the site foreman and was told the other tests had been done and he was told what to write on the test certificate.

This EIC was submitted to Anchors offices where a type written certificate was produced. The type written version had differences to Tomkins hand written version. The typed version had "P/P C Tomkins" in the single signature box for design. construction and inspection. Tomkins said in court he had not seen the typed form and he would not have consented to his signature being used. Mr Hoult the QS said that he just checked the figures on the form and signed it as the QS. he did not go to site and was not involved in the testing and inspection. Mr Hoult had known Tomkins for many years and it was alleged he knew about Tomkins status as a mate and his lack of qualifications.
 
Last edited:
None of the circuits were RCD protected, which must have been contrary in 2006 (?) and his signature has been put onto the EIC for design for the house. Then the Nice Guys didn't investigate the bang test properly which left the construction fault in place waiting.
Reading this, seems the fault may not show up on IR test during EICR unless the steel studwork is bonded (?). Also, if an RCD had been used the tragedy might well have been avoided. Appreciate any feedback ...
 
I suppose if the initial energisation, had 'blown away part of the screw and CPC', then this may not have been noted on a L-E IR test?

However, the missing continuity (on CPC) should have been noted, in the very first of the dead tests, and investigated further.
 
Incidentally, I was told of a similar fault a few years ago.

Whilst a domestic properties bathroom property was being refurbished, the plumber was getting an electric shock whilst touching a plastered wall (block construction) and copper pipe.

Turned out, landing light one of the strapper's wires in a twin & e, had been penetrated by a nail. Not touching the cpc, nor breaking the strapper wire. But made the whole wall 'live'.
 
None of the circuits were RCD protected, which must have been contrary in 2006 (?) and his signature has been put onto the EIC for design for the house. Then the Nice Guys didn't investigate the bang test properly which left the construction fault in place waiting.
Reading this, seems the fault may not show up on IR test during EICR unless the steel studwork is bonded (?). Also, if an RCD had been used the tragedy might well have been avoided. Appreciate any feedback ...
From what I can remember about the 16th edition was that cables in prescribed zones did not require additional protection buried in walls <50mm.
Circuits such as lights had a 5 second max disconnection time apart from a circuit in a bathroom which was 0.4 seconds and required supplementary equipotential bonding to pipework and all location circuit cpcs.
If it was assumed that no equipment could be used for outdoor use as was the case with a non ground floor level flat then omission of rcd protection of socket outlets may have been allowed. I'm not 100% sure of the omission tho unless others know for sure?
 
Is the steel exposed?
If not then no as it can't be touched between this and an exposed conductive part.
Is it extraneous? Can it introduce earth potential?
If not then no.
If it's extraneous then it needs bonding as you would with the gas and water services.
 
At present some of it is exposed due to the builder working on the other side of the stud wall, but once complete it wont be exposed. The fact the there will be a lighting circuit and socket circuit running through the stud wall, would this make a difference?
 
Thanks for the advise on this, ive conflictincting views from other sparks, which has made me dout my own knowledge of whats an extraneous part or not.
I think it comes down to years ago they use to make you bond everything and the kitchen sink! But systems hsve changed, and RCD's are in play now.
Its an older type plastic c/u but ive arranged it so that all circuits are RCD protected except for down stairs lights, as not enough room on that side, so all circuits upstairs and the bathroom are protected.
 

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