cables under insulation in loft

[kinnet]

A friend of mine is selling her house. Inspector has told her that all the cables under the insulation in the attic must be moved and put on top of insulation surely this is wrong.

 

[springcrocus]

The regs covering the derating cables that are buried in insulation are generally considered to be more concerned with dense foam-type insulation such as Kingspan, Celotex etc. Standard loft insulation has a high air-to-material ratio and doesn't normally affect the dispersion of heat to any major degree.

If it was a big problem, half the houses in Britain would have burnt down by now.

 

[kinnet]

Thanks thats what i told the estate agent

 

[m4tty]

Excuse my ignorance but what's an inspector mate. A surveyor ?

 

[kinnet]

Sorry mate yes a surveyor.Who i think did t have much electrical knowledge as he did t even pick up that the shower had no rcd protection.

 

[m4tty]

Most surveyors know sweet fa about electrics. Wonder if he done his cable calcs to see if the cables didn't comply after derating ffs. No chance lol

 

[Theorysparky]

They normally look at the fuseboard,,,if it looks old they report it as

'recommend wiring is checked'

muppets

 

[NozSpark]

The regs covering the derating cables that are buried in insulation are generally considered to be more concerned with dense foam-type insulation such as Kingspan, Celotex etc. Standard loft insulation has a high air-to-material ratio and doesn't normally affect the dispersion of heat to any major degree.If it was a big problem, half the houses in Britain would have burnt down by now.

I think that you'll find that this reg was written long before kingspan and the likes became commonly used in houses, insulation is insulation (ok some are better than others) it's there to retain heat and this is why we derate cables when they pass through or are installed underneath it.

In lofts you tended to only have lighting cables for which it isn't a problem. Many lighting circuits only draw 2 or 3A, 1.0/1.0 is rated at something like 11A which is more than adequate even if de-rated by 50%. The problem starts to become more aparent with shower and socket circuits where the current carrying capacity of the cable is much closer to the loads demand, therefore these cables should be at least on top of any insulation if not clipped to the rafters away from all insulation.

IMHO

 

[tom1]

I think that you'll find that this reg was written long before kingspan and the likes became commonly used in houses, insulation is insulation (ok some are better than others) it's there to retain heat and this is why we derate cables when they pass through or are installed underneath it.In lofts you tended to only have lighting cables for which it isn't a problem. Many lighting circuits only draw 2 or 3A, 1.0/1.0 is rated at something like 11A which is more than adequate even if de-rated by 50%. The problem starts to ecome more aparent with shower and socket circuits where the current carrying capacity of the cable is much closer to the loads demand, therefore these cables should be at least on top of any insulation if not clipped to the rafters away from all insulation.

IMHO

+1, bunglows are bad for it, 9.5kw + shower, socket, cooker circuits in loft layed on old insulation all covered with meter high new insulation,

 

[shed69]

I am doing a Rewire where the loft insulation guys are coming after we Rewire, spoke with Nic to confirm what I thought would be best option.. I put to them that if the shower cable is clipped to the joists and the existing bit of insulation is cleared around it before the big stuff goes over top then could I class it to air on the side of caution as ref 100... They told me I could even class as clipped direct....

The insulation guys originally asked me to leave loads of slack on cables and they would put the insulation under!! I said no chance! If you've designed for clipped direct or 100 then your cert has the date on it and your part p has a date, if something was to happen an insulation has gone in at a later date then you cannot be held responsible it's up to the firm putting the insulation in to be aware.. Are they I wonder???

There is an element of you can't be responsible for what could go in after youve done the job isnt there? It's like clipping an armoured in a garden then a year later the homeowner buries it just under a covering of soil... What's on your test sheet for ref meth at time is what it is...

 

[SPECIAL LOCATION]

A friend of mine is selling her house. Inspector has told her that all the cables under the insulation in the attic must be moved and put on top of insulation surely this is wrong.

Yes it is wrong and factually incorrect as without specific information about the actual circuit loading and protective devices used CSA of cables, no decision can be made.

Tell them to either come back with proper figures...

and assessments.

or just shut up spouting rubbish!

:C

Get a qualified competent electrician to do an "proper" inspection if you want accurate advice..

Its a bit like asking the petrol pump attendant if next car service needs a cam belt as well!?

 

[professional]

The issue of loft insulation/cable ccc`s is one that the insulation industry do NOT want to discuss.

They send in the monkeys with rolls of whatever was cheapest the day before, chuck it everywhere and staple a meaningless ticket to the roof joist - the fact that the INSTRUCTIONS on the rolls of insulation STATE that all loose cables should be lifted and placed on top of the insulation is totally ignored.

Here`s one for you :

The insulation drones can chuck insulation into a loft and blast all of the design criteria (which of course we are all aware of) out of the water - no-one bothers or cares as long as they get it done free.

A spark offers to insulate the loft after re-wiring the property - what process do THEY have to go through to ensure that the insulation is not unduly detrimental to the safety of the occupier?

Discuss.

 

[kerching]

Surveyors? I've sh1t 'em. Trying to sell late mother in laws bungalow...Surveyor did not even notice that it had slipped on the dpc by about 40mm! FFS he thought it was 'the design', until I pointed out that it was slewed diagonally ! PRANNOCKS the fricking lot of 'em. Wouldn't pay them in "coat checks".......... :coat

 

[PC Electrics]

What needs to be recognised here is that there are TWO subjects.

The first is the technical aspects of the wiring in the loft, in particular whether the existing wiring is safe and adequate in it's curent position under insulation. In this respect you should not take the word of a "surveyor". Only an ELECTRICIAN with good knowledge of the design requirements of the wiring regs (BS7671:2008 [amendment 1, 2011]) can truly report on this by inspecting the installation and checking the design against the requirements of the regs.

Then there is the aspect of selling a house. When you put a house up for sale, you do so with it in its current state, good or bad. And it is priced to reflect it's current state. Now with respect to the safety or suitability of any of the services or features of the house, there is only ONE rule: CAVEAT EMPTOR (or in English, buyer beware). There is NOTHING that the seller MUST do.

So, tell the prospective purchasers that they are welcome to make whatever changes they like once they have bought the house.

 

[SLIPSHOD & SLAPDASH]

They normally look at the fuseboard,,,if it looks old they report it as'recommend wiring is checked'

muppets

And they also normally state that there is no earth connection at the kitchen sink, so the house needs checking/rewiring !!!

 

[NozSpark]

They normally look at the fuseboard,,,if it looks old they report it as'recommend wiring is checked'

muppets

I thought that this was standard clause on their documentation so that they can transfer any liability away from themselves

 

[Technician]

Reputable loft insulation installers must provide a warranty.

Their installers need to know a few things from the guy who

did the initial assessment.

1) Conductors? condition? VIR? laid on ceiling/clipped?

2) Access hatch? sufficiently large?

3) Downlighters? are there any and where are they?

4) Bat droppings (get this- cannot be done if present because bats are a threatened species).

If they are doing their job they will not lay the material on or over

conductors and they cut it to suit so that it will not be in contact

with circuit conductors.

Some will provide fire rated hoods, but more likely will remove

the material in a circle around the fitting.

Further, properly laid, the loft will remain well ventilated.

Loft temperature will fall in winter from the moment it is laid.

The area directly under ANY header tank is left uninsulated so

that the heat will keep the tank from freezing.

Following loft insulation installation, rot in roof structure is a lot

more likely because of the fall in temperature, hence the stress

on ventilation and a lot of cowboy installers just run the material

to the roof edge, and block the air ventilation to the loft space.

If the householder has ANY damp problems, the installer is bound,

contractually, to remove it.

HTH.

 

[Manator]

In real life we all know that those who carry out this work are not trained and paid a meagre amount so will not care less. In fact some electricians do not follow the reputable methods of install and I seldom see any hold off boxes supplied for insulation. I recently failed a new install for a 32amp circuit which was installed using 4mm twin and earth which ran under over 150mm insulation. Obviously some sparks do not de rate cables either.

 

[Andrew M]

Gentlemen,

apologies for reviving an old thread but this is the nearest thing I can find online to helping solve my conundrum and I would greatly appreciate some opinions on this job.

I live in a top floor apartment that was converted 10 years ago,when I moved in there were 14 halogen downlighters in the ceiling counting the main room(10) and the bathroom(4),I've replaced all these halogen bulbs with 3w and 4w LED bulbs.

Standing in the loft there was 100mm of the glass/mineral fibre loft insulation running between the joists but a lot of pretty big gaps where the insulation had been cut to leave room around the spotilghts.
I've seen the caps that go over the spotlights to allow you to isolate them and then run more insulation and considered using them but I ended up using pretty large B and Q garden terracotta pots to cover the rear end of the spotlights.

The thing is the wiring is quite tight and wouldn't allow for lifting the wires so they would sit on top of the top up layer of insulation so I ran the wires across the top of the joists as straight as I could then layed a length of overturned square profile guttering over the cables allowing the cables to sit in a bit of pretty large trunking if you like.
I'd estimate there is at least an inch and a half between any cable and the top of the upside down guttering and probably more room laterally.

Then I layed the top up insulation ( more mineral fibre stuff) over the top of the guttering and plant pots taking a good deal of care to not upset or expose any wiring.

I've had the lights on for a few hours now and there does not appear to be a problem so far also I just used the shower and again there doesn't appear to be anything out of order, I was in there for quite a while too as I was stinking from being in the loft all day.

I would appreciate what you chaps think of all this and I'm a big boy so say it as it is because I need a few opinions before I can sign this job off in my head,as it is now I'm halfway to going back up there now and uncovering the shower cable but in the same breath I think I'll let it sit for a few uses first as well.

Sorry but I have no idea about what kind of cables have been used up there but the shower cable looks like a real beast compared to the lighting runs.

Many thanks in advance.

 

[Andy™]

for the lighting cables, your unlikely to have any problems with the insulation. for the shower cable, at least put it on top