# Forum Home Renovation Lighting  downlights

## soprano1

Hi, 
Ive just had some electrical work done by an electrician, and my question is whether tis is safe. Ive got some downlights (5 off ) in an extention that was done before i purchased the property and i wanted 5 more. Now my question is can he just add these new ones to the existing ones and also he has used 2,5mm cable to do it? is this safe?

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## achilles

it all depends on how many other lights are on the existing circuit, if he has used 2.5mm cable back to the switch board then you can use a higher rated circuit breaker for the lights, but i doubt it. Lighting circuits are usually run in 1.5mm cable.
But i think you should be right with 5 more.

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## elkangorito

The sparky may be using 2.5mm cable due to it being covered in thermal insulation (fibreglass bats).
If this is the case, the circuit breaker must be rated for a maximum of 16 amps & the reason why the cable has been derated, must be written in the switchboard.

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## applied

The sparky may be using 2.5 because that's what he had a short roll of in the van which would otherwise go in the scrap bin.

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## chalkyt

2.5mm cable is rated at 27A in free air but derated to 13A if completely surrounded with insulation. Even at 13A, assuming that your downlights draw 1/2 A each, you could run 20+ lights. So, the likely answer as above is that he probably had some 2.5mm in the van. The installation sounds perfectly safe, although my view is that it is not great practice to change cable size unless there is a really good technical reason for it. 1.5sq mm cable is the usual size for lighting.

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