A loft wiring horror story - November's Speakers' Corner

The loft had been insulated to meet current Part L regulations. So the loft cabling was totally covered. When moving the loft insulation to inspect the GU10 cabling to my horror I found the connection to the light fitting severely burnt and the wiring severely scorched for about 250mm. And after that the wiring PVC had 'hardened' due to the effect of heat.

Photos are attached. I reported this to the letting agency and subsequently wrote a report to the building company, these properties are less than two years old. My fix was to replace the wiring, install IP and Fire Rated SELV recessed fitting and leave a thermal gap around the light fittings for heat dissipation.

There was also another issue with damp air being pulled along the ceiling across the face of the GU10 units and thus damp air being drawn in to the units by convection heat from the GU10 lamps, hence my upgrading to IP rated units. I recommended and inspection of similar properties at the time. Well all went quiet with no feedback. Then about two weeks ago a similar call from a similar property on the same development. Guess what? Exactly the same problem! So same remedial action and a second report and photographs! Still no feedback.

This issue of Part L and Part P conflict regarding insulation is becoming a real menace. What I mean by that is that even with fire hoods or similar there is questionable effect of good heat dissipation. Roll on adequate LED lamps at a reasonable price to eliminate the heat issues with halogen lamps! Would welcome feedback/advice from readers with similar experiences.

Regards,
 
R J Spencer
RJ Electrical Services

This Speakers' Corner winner had quite response from Voltimum users.  Please read what the electrical community had to say below:

BASEC has seen similar problems, in one case resulting in a serious fire.  Halogen lights can generate and emit significant amounts of heat, particular the open-frame type.  If surrounded by thermal insulation, either in a loft or in sloping ceiling spaces, or if an enclosure is sealed as in outdoor lighting, this can result in problems for the supply cable.  If cables are run hotter than their rated temperature, then they can fail quite quickly – lifetime may be halved for every 7 degrees C above the rated temperature.  Using a low smoke halogen free type of cable such as to BS 7211 can give slightly better protection because such cables are rated at a higher temperature.  However, even this would not be effective if the fitting is completely covered in thick insulation.  Another potential problem to watch out for on inspection is the air-blown paper fibre type of insulation, which could result in combustible insulation in direct  contact with light fittings.

Dr Jeremy Hodge, Chief Executive, BASEC

I have been following the discussion re Insulation and think that the following point should be made.

Insulation installers are only there to do a job and it is fair to assume that they have no prior knowledge of electrical circuits and the effects of enclosing them in insulation.

I do some part time teaching at local colleges and have raised this on many occasions with colleagues as to necessity of recalculating the cable sizes.  Maybe the time has come to use more  LSF  due to its higher  temperature  range as many people are now extending above garages. Building Inspectors require that insulation also goes in the floor space as well as the loft space above and this can mean downstairs lighting circuits need re-rating.
As I see it surely the onus must lie with the Building regulations authority to have published a warning of the possible consequences to householders prior to insulation being fitted.

It is they that have have really pushed this and as much as I agree it is required in our attempts to reduce energy usage and thereby the overall  carbon footprint. Warning should have been posted at the same time.

I think that the horrors section is a very good area for all electrician to read as it really brings home the necessity of using "Best Practice".

(Jeff Rhodes) Rhodes Services

I have also come across similar situation however this was in a bathroom (which was in a posh basement conversion)where the development was 6 months old and a standard GU10 fitting with no IP rating I actually saw it ARC when the resident put the MCB  ON so that he could show me the problem.....Anyway I stopped him immediately and on further investigation found that the insulation burnt away for 150mm and the insulation scorched around it!!!  That was it for me I informed the landlord that all the fittings needed to be changed and disconnected the bathroom downlighters –(there was a shaver light).  Guess what.... the landlord has never paid since I obviously document this he has avoided me .....Apparently the building inspector passed this???

Dal, A1 Affordable Services Ltd.

Ref: RJ Electrical Services letter - I am slightly amazed that we are expected to be surprised by this event. Let me explain.

We all know we are facing very hard times at the moment, the electrical services industry has been very badly effected. Many reputable companies have been forced to cut back on labour, and to cut all profit margins down to the absolute minimum.

The sudden increase in ten week courses, and the acceptance by governing bodies, has resulted in these sort of occurrences being common place. It is not a building regulation in conflict with electrical wiring regulations, it is very poor understanding in design, and  suitability in use.

Whilst we all can sit in the comfort of our homes and be appalled at the graphic illustration of the effects of our neglect, there  are many more that go un reported. How do we control and manage our industry?

Well I have no idea how the scheme providers think, but I have always thought that the idea that the applicant chooses the shown assessment jobs, is a very bad idea. Open to abuse especially from a DI (Domestic Installer) point of view. You could under the current system do 1000 jobs but only conform to the regulations in two of those to be found to be compliant.

A far better way, would be for all scheme providers to pick from the list of notifiable works that the applicant has supplied and spot check them, with or without the applicant present.
Radical I know, but very effective in preventing the very issue Part P was set up to combat.
One day I can see Part P will come back to bite the very people who set it up, because they opened a back door, that should never have been opened. If electrical safety is the main concern, then please stop these ten week I am an electrician courses.

Steven Forsyth

I can only echo that experience having found retrofit insulation contractors placing massive additions to the loft insulation with absolutely no regard to heat generating sources below, or the effect on cable ratings which would not normally be picked up in later wiring test and certifications. This is common in bungalows where the ring mains are most often run through the loft space. There is also the potential physical danger  to anyone who has to enter the loft space and try to find services buried by insulation. How often have we opened the ceiling trap door only to be faced with a sea of insulation with no safe places visible to walk on the joists.

Is it not time for the insulation contractors to also be bound by regulations regarding the dangerous ways they can apply insulation?

David Prewett, S.I.R Cirencester