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

 

[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 ?