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

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.

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.

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.

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.

 

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.