Cooker and kitchen power cables to be enclosed in rockwall

[chris murphy]

Hello All,

I have just found out that a family member who is having some Building work done has been advised to insulate above the Kitchen ceiling of their flat with Rockwool type insulation - above their ceiling and into the floor void of the flat above.

I have told them that Electrical POWER cables should not be contacting insulation - what has been proposed would mean the cables complely enclosed with insulation above and around them.

The reason why I have included Urgent in the title of this thread is that the Builders have already pulled down the ceiling are are planning to fit the insulation tomorrow / Tuesday 16th.

The flat upstairs has a Cooker cable [10mm] and a Kitchen ring circuit which supplies quite a few double socket outlets some of which have 2 x 3kw appliances connected which are used at the same time - there is also a Washing machine etc. on the circuit.

My family member asked me to write down what I thought about this not being allowable - I hope that I am right - here is what I wrote - Sorry that it is so long winded I was trying to make it easy for them to understand and explain to the Builder - could any Member comment and tell me which Electrical Regulation governs this please:

QUOTE:

There definitely are issues with insulation fitted where it comes into contact with some Electrical power cables - the contact with insulation can cause the cables to heat up - a possible fire risk below the floor / above the ceiling.

Electrical power cables are supposed to be installed so that any heat generated just dissipates into the surrounding air - they are definitely not supposed to be insulated against that happening even because of just one surface of the cable contacting insulation.

Also depending upon the length of the cable that is in contact with the insulation this can cause the cable power carrying capacity to be diminished.

I would have expected your Builder to know at least that electrical POWER cables [not lighting cables] should not be contacting insulation even if they did not know about the possible power carrying capacity being diminished.

Examples of Electrical cables that should not be in contact with insulation are:

A cable to a Cooker point where as much as 8 - 10 Kilowatts of power can be drawing through the cable if the cooker or Oven and Hob are in full use - such a cable contacting insulation is definitely not allowable.

However even normal ring circuit 2.5mm cables to household electrical double socket outlets where 2 appliances are connected can be drawing 2 x 3 Kilowatts for example and should not be in contact with insulation - but in a Kitchen in rare circumstances the ring circuit cables could be drawing as much as 7 or 8 Kilowatts.

That is definitely too much power to be running through electrical cables that are in contact with insulation.

Where possible a lack of knowledge / unawareness of the above facts with some Builders could
originate from is this:

There are Millions of homes all over the UK that have loft insulation - that insulation is more often than not laid over the Electrical lighting cables in the roof space although there are now
Electrical Regulations that specify that should not be done.

However the reason why that has been previously allowable and there is usually no danger to the home is because there is a very low amount of power being drawn through those lighting cables so there is no possibility of the cables heating up or any power carrying capacity being diminished by contact with the insulation.

POWER cables coming into contact with insulation compared to Lighting cables are a totally different matter.

END OF QUOTE.

If I am basically correct in those details could Members let me know what regulation covers this so I can let my family member know and hopefully enable them to prevent a possibly dangerous situation from being created.

Thanks to all who have read this.

Chris

 

[nicebutdim]

There is no regulation which prohibits insulated and sheathed cables being in contact with, or surrounded by, insulation. In a new installation this should be taken into account at the design stage, along with many other factors, and current carrying capacity of cables de-rated accordingly.

You are right to highlight the issue and a builder should know better than to surround cables with insulation in this manner, without first consulting someone with appropriate expertise. In reality builders will often do exactly as they please and many care little about regulations or potential hazards. The other side of this is that circuits are likely to be subject to much lower loads than you might think, with higher current generally being carried for limited periods of time. Exceptions would be fixed loads such as an electric shower or immersion heater.

It would be prudent to urge your family member to engage the services of a competent electrician, but there's not much you can do if instead they decide to place their faith in the builder.

 

[chris murphy]

There is no regulation which prohibits insulated and sheathed cables being in contact with, or surrounded by, insulation. In a new installation this should be taken into account at the design stage, along with many other factors, and current carrying capacity of cables de-rated accordingly.

You are right to highlight the issue and a builder should know better than to surround cables with insulation in this manner, without first consulting someone with appropriate expertise. In reality builders will often do exactly as they please and many care little about regulations or potential hazards. The other side of this is that circuits are likely to be subject to much lower loads than you might think, with higher current generally being carried for limited periods of time. Exceptions would be fixed loads such as an electric shower or immersion heater.

It would be prudent to urge your family member to engage the services of a competent electrician, but there's not much you can do if instead they decide to place their faith in the builder.

Hello nicebutdim,

Thanks very much for your reply.

I am surprised that there is no regulation to cover this situation even for high power draw cables supplying Electric showers or Immersion Heaters which I assume could become a fire hazard if enclosed in insulation ?

I understand your explanation about the normal Kitchen circuit cables and a Cooker cable only carrying high current draw for limited periods of time so unlikely to cause the heating up that I described when enclosed in insulation.

I was probably formulating my opinion / stating what I wrote having remembered a situation where I confirmed that an Immersion Heater cable running across a roof space and covered in insulation should not be allowed to stay like that because of possible overheating of the cable.

That was also in the home of a family member - an elderly person - I was able to go into the roof space and lift up the cable so that most of it was above the loft insulation and I put strips of hardboard under the sections that could not be clipped above the insulation.

I had previously felt that the cable did get very warm when the insulation was on top of it and the shower was running.

I think that I may have either asked about it on a thread that I posted on here or possibly become involved in a thread posted about something similar and asked about that.

So I would be basically correct in what I wrote if it was about an Immersion Heater cable or an Electric Shower cable but not just a Cooker cable or Kitchen ring circuit cable ?

My family member will be telling the Builder what I wrote tomorrow - I may not be able to contact them before that to explain that I was wrong.

Normally I would have tried to get an answer on here before giving anyone my opinion about anything Electrical.

But they were going out for the evening and will not be back until late and because the insulation work was due to start in the morning I thought that I was doing the right thing by telling them what I thought - "Woops" !

I will not be making that mistake again.

Thanks again for your interest and knowledge I really appreciate your help with this.

Chris

EDIT:
I edited my previous message to change the details about what is being used in the Kitchen of the Flat above my family member - the cables to that Kitchen are the ones that will be being enclosed in insulation.

Your suggestion about engaging a professional Electrician is always a good one but if you were on site at my family members home and found out about the cables being enclosed in insulation what would you have suggested ?

 

[Dan]

@chris murphy please don't use all caps in thread titles it's really annoying re-writing it out for you. Cheers. Admin.

 

[nicebutdim]

It's not at all surprising that no such regulation exists as insulation is just one of many building materials through which cables need to pass. Cables are installed in a range of different ways and we have regulations which dictate how those installation methods affect current carrying capacity. This is an intrinsic part of the design process and dictates the size of cable used for specific applications.

If this was a member of my family, I'd explain why it might not be a good idea to pack insulation around existing cables and probably try to quickly figure out what, if any, actual risk was involved. If I advised against the installation of insulation around certain cables, I'm not sure there's much I could do if they ignored my advice in favour of their builder's recommendations.

The situation you describe is not particularly uncommon.

 

[chris murphy]

@chris murphy please don't use all caps in thread titles it's really annoying re-writing it out for you. Cheers. Admin.

Sorry - I usually do this on documents / instruction sheets when typing the title so it is a habit.

Also tonight In thought thatit might make my urgent request for help stand out in the thread list.

I will definitely try to remember not to use all capital letters in the thread title when I post my next one but if it is a long time from now I may not remember because of my document title habit.

My Regards,

Chris

 

[felix24]

Just a query, if the cavity contains the cooker wiring from the flat above, does the cavity actually belong to the flat above, or the flat below, or is it a shared space? Might have to check the deeds to make sure?

I would definitely suggest getting an experienced electrician to check this out.

Unless the insulation is going to totally fill the cavity, it may be possible to suspend cable tray from the floor joists to run the cables through to keep them clear of the insulation?

 

[chris murphy]

It's not at all surprising that no such regulation exists as insulation is just one of many building materials through which cables need to pass. Cables are installed in a range of different ways and we have regulations which dictate how those installation methods affect current carrying capacity. This is an intrinsic part of the design process and dictates the size of cable used for specific applications.

If this was a member of my family, I'd explain why it might not be a good idea to pack insulation around existing cables and probably try to quickly figure out what, if any, actual risk was involved. If I advised against the installation of insulation around certain cables, I'm not sure there's much I could do if they ignored my advice in favour of their builder's recommendations.

The situation you describe is not particularly uncommon.

Hello again,

The reason why I thought that there would be a regulation about electrical cables and insulation is because during the last 30 years or more including at present existing cables are being enclosed / covered or at least contacted by insulation as part of energy efficiency improvements to millions of Home`s and other Buildings.

Your point about electrical cables having to pass through a Building fabric / through Building materials such as insulation in new builds and that being factored into the Electrical Installation design is very valid but nothing is specifying what should or should not be done when insulation is being fitted above or around existing and possibly old electrical cables.

In the absense of the need for an Electrical regulation covering this I would have thought that a Building Regulation relating to Electrical installations or the fitting of various types of insulation should cover it.

Just my opinion - Thanks again for your time.

Chris

 

[nicebutdim]

Hello again,

The reason why I thought that there would be a regulation about electrical cables and insulation is because during the last 30 years or more including at present existing cables are being enclosed / covered or at least contacted by insulation as part of energy efficiency improvements to millions of Home`s and other Buildings.

Your point about electrical cables having to pass through a Building fabric / through Building materials such as insulation in new builds and that being factored into the Electrical Installation design is very valid but nothing is specifying what should or should not be done when insulation is being fitted above or around existing and possibly old electrical cables.

In the absense of the need for an Electrical regulation covering thisI would have thought that a Building Regulation relating to Electrical installations or the fitting of various types of insulation should cover it.

Just my opinion - Thanks again for your time.

Chris

I've explained twice that there are regulations - just not a regulation prohibiting it as you suggested there ought to be.

 

[chris murphy]

Just a query, if the cavity contains the cooker wiring from the flat above, does the cavity actually belong to the flat above, or the flat below, or is it a shared space? Might have to check the deeds to make sure?

I would definitely suggest getting an experienced electrician to check this out.

Unless the insulation is going to totally fill the cavity, it may be possible to suspend cable tray from the floor joists to run the cables through to keep them clear of the insulation?

Hello Felix24,

I have wondered for decades about ownership of the above ceiling / underfloor void from an upstairs flat - I have never been able to find the answer to any property despite over many years asking almost everyone that I know who owns a flat.

I have asked some people whether there is anything at all about this on their deeds but anyone who could access ther detials on their deeds stated that there was no reference to that.

I would have thought that the ceiling would be the upper boundary of a flat ownership although we know that lighting cables for ceiling lights will have been run in the void between the ceiling and the floor above.

The insulation is planned to totally fill the spaces between the joists from above the ceiling to the underside of the floorboards above - approx. 200mm with then insulated plasterboard below that to form the new ceiling.

This is stated to be mainly for soundproofing but also it would help retain heat in the Kitchen which is a big room.

Thanks for your reply.

Chris

 

[chris murphy]

I've explained twice that there are regulations - just not a regulation prohibiting it as you suggested there ought to be.

Hello again,

The last thing that I wanted to do was to irritate you.

I did refer to what you wrote about there being regulations about this for new build properties with cable types / sizes and runs being designed to allow them to run through various Building materials including insulation without any detrimental effect on the installation.

I was just giving an opinion about insulation being fitted in existing Homes / Buildings on top of or around existing electrical cables.

Chris

 

[felix24]

Hello Felix24,

I have wondered for decades about ownership of the above ceiling / underfloor void from an upstairs flat - I have never been able to find the answer to any property despite over many years asking almost everyone that I know who owns a flat.

I have asked some people whether there is anything at all about this on their deeds but anyone who could access ther detials on their deeds stated that there was no reference to that.

I would have thought that the ceiling would be the upper boundary of a flat ownership although we know that lighting cables for ceiling lights will have been run in the void between the ceiling and the floor above.

The insulation is planned to totally fill the spaces between the joists from above the ceiling to the underside of the floorboards above - approx. 200mm with then insulated plasterboard below that to form the new ceiling.

This is stated to be mainly for soundproofing but also it would help retain heat in the Kitchen which is a big room.

Thanks for your reply.

Chris

Hi Chris,

At the very least, I would advise having a chat with the upstairs neighbour, as there is potential for their electrical installation to be affected. If it does later result in a problem, I would guess the cabling would have to be accessed through your relative’s new ceiling, so probably best to get this sorted now.

If the cable is fully enclosed in 200mm insulation, that will reduce the current carrying capacity of the cable by much more than if the cable just makes contact with the top of the insulation. If there is a way to clip the cables to the underside of the floor joists, so they have air above them for the majority of the run to dissipate heat, that would have less effect. I think it is also permissible to make small notches in the joists, or even to put cables through holes drilled in the centreline of a joist, but again, I would advise involving the upstairs neighbour and a professional electrician before doing anything decisive!

Hope it all gets sorted for you,

Felix

 

[chris murphy]

Hi Chris,

At the very least, I would advise having a chat with the upstairs neighbour, as there is potential for their electrical installation to be affected. If it does later result in a problem, I would guess the cabling would have to be accessed through your relative’s new ceiling, so probably best to get this sorted now.

If the cable is fully enclosed in 200mm insulation, that will reduce the current carrying capacity of the cable by much more than if the cable just makes contact with the top of the insulation. If there is a way to clip the cables to the underside of the floor joists, so they have air above them for the majority of the run to dissipate heat, that would have less effect. I think it is also permissible to make small notches in the joists, or even to put cables through holes drilled in the centreline of a joist, but again, I would advise involving the upstairs neighbour and a professional electrician before doing anything decisive!

Hope it all gets sorted for you,

Felix

Hello Felix24,

The Electrical cables in the floor void of the flat above are existing.

Depending upon their direction across the Kitchen area some are in holes drilled through the approximate centre of the joists and some that are routed along the run of the joists were just laying on the ceiling before it was pulled down - now just hanging below the joists until the insulation pushes them up to just under the upstairs flat floorboards.

The cables that will just be pushed upwards by the insulation will be laying on it and probably touching the under side of the floorboards and the cables that are routed through the centre of the joists will be completely enclosed by the insulation.

Any future access to the upstairs flat cables would still be from their home - taking up the floorboards that were lifted to carry out the most recent rewire but of course the insulation would be more than just a bit of a nuisence if a future Kitchen rewire was required.

My family member has informed the neighbour upstairs and they are very pleased to know that sound proofing insulation is being fitted because downstairs have 3 young children who can be very noisey - screaming when playing just like most young children.

Now that I have written wrong information to my family member and embarrassed myself I will probably stay out of any futher involvement.

Thanks to Members who have read this thread and to You and Member nicebutdim for your replies.

Chris

 

[littlespark]

You haven’t embarrassed yourself.

You’ve brought up what could be a problem…. Showing some extra thought needs to go into this rather than just “we’ll stuff it full of rock wool”

Heat dissipation is a problem…. Even some low temperature LED downlights, fitted into a ceiling still ask that insulation doesn’t cover the fitting.
(There’s no downlights going in this new kitchen ceiling, is there?)


The builder might take the hump, but they’re known for it.

Could the same sound deadening be obtained by solid slabs of insulation, fitted below the cables?

 

[nicebutdim]

Hello again,

The last thing that I wanted to do was to irritate you.

I did refer to what you wrote about there being regulations about this for new build properties with cable types / sizes and runs being designed to allow them to run through various Building materials including insulation without any detrimental effect on the installation.

I was just giving an opinion about insulation being fitted in existing Homes / Buildings on top of or around existing electrical cables.

Chris

There was no irritation on my part - I just thought you'd missed the point. The same regulations apply whether the installation is new or old, but it's not easy forcing other trades to inform themselves on issues affected by their work.

 

[oscar21]

Insulation doesnt cause cables to heat up, it just stops them dissipating the heat they produce. If a cable doesnt get warm in free air it wont get warm in insulation.

 

[chris murphy]

Insulation doesnt cause cables to heat up, it just stops them dissipating the heat they produce. If a cable doesnt get warm in free air it wont get warm in insulation.

Hello oscar21,

When I wrote about cables heating up I meant that IF a cable heated up that heat could not dissipate correctly if the cable was enclosed or contacting insulation.

I would have thought that as we know some domestic electrical installation cables definitely do heat up - for example those supplying sockets that are powering 3Kw fanned convector heaters - rockwool or fibreglass insulation completely enclosing those cables and preventing that heat from dissipating cannot be good for the long term condition of the cable insulation ?

As I am sure that we have all seen many homes have those types of Convector heaters - often remaining permanently plugged into the same socket rather than moved around the home`s rooms so the cables powering those sockets will be heating up regularly possibly for many years and where those cables are enclosed in insulation surely that cannot be O.K. ?

The Builders who are involved in my family members flat have said that when they are doing works in flats that involve sections of ceiling having large holes created such as when there are walls being removed or where ceilings are badly damaged / badly cracked they always suggest Soundproofing insulation is fitted.

After hearing what they said to my family member the wording sounded like they were trying to suggest that it was required by the Building Regulations which would have been totally misleading for an existing property / flat - unless I am guessing when ceilings have to be pulled down perhaps soundproofing insulation would then be a requirement of the Transfer of Sound regulations ?

I mention that because I do know that this type of Soundproofing is becoming more popular in refurbishments where enough dirty / dusty work is being carried out that pulling down ceilings is not seen as prohibitively messy for the property in terms of additional dust etc.

My comments on this thread and on any other Electrical matter / Electrical question are only my perceptions I would never try to actually argue or debate any technical point with Electricians on here.

I would never even attempt to answer a question about Electrics on here.

I originally joined the Forum many years ago to ask some Electrical questions about my own home and after receiving that help I decided to give back help to members who had posted threads asking questions about Heating systems that were not only electrically based [pipework queries / possible faults etc.] by responding to those types of questions.

Some years after that members were directed to post those types of questions on the UK Plumbers Forum so I have not been able to help any further on here but I have still been able to receive help with some of my questions such as on this thread.

Thanks to the Members who have replied to me and to those who have read this thread and my others.

Chris

EDIT: The questions that I referred to above that I had posted many years ago when I joined this excellent Forum about the Electrical installation in my home are no longer showing on the My Content list perhaps due to a previous Forum reorganisation ?