Are cables covered by loft insulation a fire risk?

[Guest simonDent]

I am seeking advice re roof insulation and wiring, we are living in a rented property and have just had an extra 200mm of loft insulation laid, however this insulation has been laid over existing wiring and also a wiring junction box that powers the light and an aerial splitter/receiver so i am just seeking advice as to wether or not this is safe?if it were my property I would install safety boxes and lay wiring on top of joists as a precaution but as I mentioned this is a rented property.

Please advise

Kind Regards

Simon

[Tom Sutton]

It depends on the type of insulation used and if the wiring has been installed according to the IEE regulations? For instance if fibreglass was used it is non-flammable and therefore unable to ignite, thus unable to add fuel to a fire. Secondarily if the wiring has been installed correctly any faults that could cause a hot spot, because of the lack of ventilation, would trigger the RCCB before a fire could ignite any flammable materials.

[Tom Sutton]

It has been brought to my attention the term I had used above ECB, which now I have changed, stood for Electric Circuit Breaker I should have used RCCB (Residual Current Circuit Breaker) sorry for giving a bum steer.

[Tom Sutton]

My mistake has raised an important point the term ECB would include the old fashion wire fuse box, which can be misused, I have seen multiple strands of fuse wire used, tinfoil, safety pin and even nails. They had caused fires and one was a fatality so it is important that the RCCB consumer box is now the norm for most premises.

[William Dickinson]

Covering Electrical wires with loft insulation does reduce the current carrying capacity of the wire.

For example 1.0mm Twin and earth cable  that quite safely fed the upstairs of a house will have it's rating reduced, this means in some circumstances the loft wiring that is covered deep in insulation would need upgrading to 1.5mm.

 

[titch2k6]

To know for sure, you should have some knowledge of the IEE Regulations, particularly Tables 4D1A to 4F3B (Current carrying capacities & Voltage drops) in the current Edition, and work it out. A lot depends on the reference (fixing) method, length of run, cable load (using P=VI to work out), thermal allowances (ambient and conductor operating temperatures), cable type (flexible, T&E, Armoured), core type, etc.