Badly insulated Attic in New house

stwome01

I live in a 6 year old 2 storey semidetacted house. Recently I decided to check the insulation in the attic. There was 200mm of insulation down so I decided to add 150mm on top (there was no 100mm at my local store). Anyway when I was insulating the attic I notice two things that shocked me.
1) the builders had insulated under the water tank (I have now removed this)
2) the builders had laid the existing insulation on top of most of the wiring.

I am concerned that there might be high current cable underneath the insulation. I assume I would be better going through the attic and uncovering this wiring. Is there likely to be much of this in the attic. Cooker, washing machine, etc are all on the ground floor. An electric shower is the only high current item on the first floor. Is regular wiring safe under insulation (lights, sockets etc). Also I assume I'll be able to identify high current cable by there greater thickness?

I'd appreciate any advice. Thanks,
Seán

Buford T Justice

Wiring should not be under any insulation, it may cause issues with heat dissipation from the cable.

cuculainn

Fingers McGee wrote: »

Wiring should not be under any insulation, it may cause issues with heat dissipation from the cable.

Our home house recently got insulation installed in attic. there was already insulation between the joists......but all the new insulation was laid over the wires.......this was even inspected by SEAI..........should I be looking to get this rectified??

Buford T Justice

cuculainn wrote: »

Our home house recently got insulation installed in attic. there was already insulation between the joists......but all the new insulation was laid over the wires.......this was even inspected by SEAI..........should I be looking to get this rectified??

In a word - YES,

If you have, for example an electric shower which is running on 6square cable, there is the potential for the cable to generate heat due to the load running through it. If this is between two layers of insulation then it won't allow the heat to dissipate, and could overheat and melt the cable.

fodda

Could you get white plastic waste pipe and cut it and then cover cables and then re-lay insulation over the cables/wastepipe?

Then the cables would be in their own 35-50mm trunking, would that be any good?

youtheman

stwome01 wrote: »

1) the builders had insulated under the water tank (I have now removed this)
2) the builders had laid the existing insulation on top of most of the wiring.

1. The SEAI recommend that you don't insulate under the tank, unless the tank is greater than 300 mm off the ceiling level.

2. In theory you shouldn't insulate over cables, but when a house is wired you'll have a maze of cables running across the ceiling. I've personally never seen insulation that wasn't put over cables (but I'll readily admit that my experience is limited to my own house and any neighbour's house that I've visited). I'd like to know how you can 'blow in' insulation and not cover the cables. I'd be happy to just not cover large power cables to items such as power-showers.

In summary, I'd say that the OP's house insulation is in line with 99% of all house built (though I'm open to correction here).

cuculainn

Fingers McGee wrote: »

In a word - YES,

If you have, for example an electric shower which is running on 6square cable, there is the potential for the cable to generate heat due to the load running through it. If this is between two layers of insulation then it won't allow the heat to dissipate, and could overheat and melt the cable.

So would it be enough to just uncover the heavy duty cables such as electric shower etc?

That wouldn't be a big job, but it would be almost impossible to uncover every wire as there is a maze

Buford T Justice

Anything that would be taking a discernible load would need to be uncovered. Maybe not lights, but definitely the shower and the socket cables.

stwome01

Thanks for the all the advice. I have started uncovering most of the wires. It's a pain but I will sleep better once it done. It's fustrating that the builder didn't do the job right in the first place.

EosEnergy

Personally I wouldn't bother lifting cables above insulation, for one reason.
If ANY cable is getting so warm, then your house is going to burn down anyway!
Heat should only develop in the device - water heater or whatever, the exception is where you have a junction box - heat can develop at the junction if not correctly connected but there should be no junction on a heavy load device such as a heater.

It should be possible to run a "power shower" for hours with no detectable heat in the cable, any other result demands replacing/rewiring.

One big exception is these damned downlighter ceiling lights, so popular with the glossy-magazine brigade, they get extremely hot and MUST have firehoods fitted before insulating.

Buford T Justice

EosEnergy wrote: »

Personally I wouldn't bother lifting cables above insulation, for one reason.
If ANY cable is getting so warm, then your house is going to burn down anyway!
Heat should only develop in the device - water heater or whatever, the exception is where you have a junction box - heat can develop at the junction if not correctly connected but there should be no junction on a heavy load device such as a heater.

It should be possible to run a "power shower" for hours with no detectable heat in the cable, any other result demands replacing/rewiring.

One big exception is these damned downlighter ceiling lights, so popular with the glossy-magazine brigade, they get extremely hot and MUST have firehoods fitted before insulating.

This is bad advice. The recommendation is that electrical cables must not be covered in insulation for the reasoning above. This is not just from me. All insulation manufacturers as well as electricians recommend this.

You're statement about the house burning down is scaremongering.

gsxr1

i have to agree with advise over leaving it alone. Just pull up the high current devises cabling.

dnme

gsxr1 wrote: »

i have to agree with advise over leaving it alone. Just pull up the high current devises cabling.

How do you know which cable is high load?

EosEnergy

Fingers McGee wrote: »

This is bad advice. The recommendation is that electrical cables must not be covered in insulation for the reasoning above. This is not just from me. All insulation manufacturers as well as electricians recommend this.

You're statement about the house burning down is scaremongering.

I knew I was sticking my neck out a little - not scaremongering but anyone with a hot cable anywhere in the house should be alarmed, and immediately call an electrician.

PVC coated cables (nearly all cables in common use) should never be in contact with polystyrene and many other plastic insulation materials as the cable can be chemically attacked.

Heavier load cables are simply bigger - more copper in the conductors can carry the load without getting hot.

Yes, placing these heavier cables over the insulation is the most I'd expect to have to do, rather than move all of them.

gsxr1

dnme wrote: »

How do you know which cable is high load?

generally it would be the thick cables. Like the shower .

Cranky Mc Funhouse

OP please consult an electrician it will put your mind at ease since all you seem to be getting here is differing opinions. Also be aware that the shower is not the only heavy load in the house, the longer the cable the more current it draws.

BostonB

How do you "pull up" the cables. Mine have no slack on them to pull them anywhere.

fodda

So if you were to put them in some trunking/conduit like 1.5" or 2" kitchen waste pipe and then replace the insulation over them would this be ok being as they have an inch or so to disperse heat you say they generate?

gsxr1

BostonB wrote: »

How do you "pull up" the cables. Mine have no slack on them to pull them anywhere.

you cant. You will do more harm than good.

this is beginning to turn into a storm in a tea cup.

If your house has survived this long, its unlikey this small problem is going to start a fire now.

paddy147

Right so,you pull your cables up so that they rest "ON TOP" of the insulation,

But what do you do then,when you have loft boards or even insulated loft boards fitted in your attic.

Becasue then you are just trapping the cable between the top of the insulation and the underside of the loft board.

So what are you meant to do??

Buford T Justice

paddy147 wrote: »

Right so,you pull your cables up so that they rest "ON TOP" of the insulation,

But what do you do then,when you have loft boards or even insulated loft boards fitted in your attic.

Becasue then you are just trapping the cable between the top of the insulation and the underside of the loft board.

So what are you meant to do??

Aren't the loft boards soft underneath? Couldn't you cut a groove in the back of the board? or into the rafter if needs be?

@EosEnergy, Most cables don't have issues with heat because they have the ventilation around them to dissipate the heat when / if needed. Insulating them will reduce their ability to dissipate it.

@OP, just make sure the heavier cables aren't insulated. Most lighting circuits don't really have issues with big loads, so they would be ok, but sockets to be on the safe side. You just need to make sure there is an area around the cable to allow the heat to effectively dissipate.

@ GSXR,Thats true, but I don't want to be giving out bad advise here, or anything that would contradict regs.

There was an issue on the P&H forum where a poster was told to bypass his boiler stat, and it would be fine for a while. It wasn't and he burst two pipes in his house as a result. Better safe than sorry.

chuchyface

I put some 2x2 down on top of the attic joists (running in the oposite direction) before I put down the loft boards so as to avoid squashing the cables. 2x2 are probably a bit heavy but had some lying around that wanted to use up anyway.

fred funk }{

I think there's a lot of confusion in here. The load on the cable is irrelivant once the cable is of the correct gauge. So saying 'just don't insulate the large cables' is a mistake because it's more than likely any cables that will get warm are cables that are too small for the load they're carrying.
I would certainly not worry about covering the cables with insulation. Your house is a modern house with modern regulations and modern high grade electrical cable. Some houses have no attics at all and all the wiring is through the walls and ceiling which are insulated and iv never heard of and problems.

paddy147

chuchyface wrote: »

I put some 2x2 down on top of the attic joists (running in the oposite direction) before I put down the loft boards so as to avoid squashing the cables. 2x2 are probably a bit heavy but had some lying around that wanted to use up anyway.

Looks like a good diy job there.:)

JOSman

EosEnergy is right. If any cable is getting warm than its carrying too big a load and the wrong gauge is being used. At this stage I'd certainly bring in an electrician.

This is why it shouldn't be an issue with putting insulation over cables as specs should be high enough to carry necessary load. Of course this is providing that you don't have 5 million+ items plugged into the same socket.

In addition, all the above statements are in breach of some EU guideline with really long initials.

payitforward

After 12 years of lagging attics and seeing what can only be described as n net of wires imposible lift up with out harm to employee's.I suggest we are banging on the wrong door.leave the wires alone unless you do want to burn down your or else get electricuted. This is an electrian job to have tidy electrical work in place , and should be of great concern to H.S.E.