# Forum Home Renovation Electrical  Light circuit in insulated cathedral ceiling

## Compleat Amateu

G'day All.  I'm gradually retrospectively insulating a series of rooms with cathedral ceiling, either by removing the plaster linings and adding insulation from below, or removing tiles and adding from above.  In either case, the result is plasterboard-insulation-sarking-tiles all in approx 140mm layer.
What's the best way to protect light circuits from getting too hot?  Leave them lying on the plasterboard and under the insulation?  On top of the insulation and under the sarking and tiles?  Or enclose the cable in a conduit - which would be a PITA in retrofit, but can be done.  Am I over-thinking this?
Cheers

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## chrisp

Don’t worry about trying to keep the cable cool, it is more important that the cable not carry more current than it safely can once ‘fully surrounded by insulation’. What you need to do is call your electrician and have them change the circuit breaker to suit the current carrying capacity of the cable in insulation.

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## Bloss

Get a sparky to check - usually just needs RCBOs to replace fuses or old style breakers and a slight derating of the circuit that in practice usually has no impact. For example an older fuse might be 20amp and would be replaced by a 16amp RCBO. An old light circuit might have a 10amp fuse and gets an 8amp RCBO. This vid explains well https://www.youtube.com/watch?v=iguJS6hUIzQ

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