Bathroom light pull switch - Cable size

[NewOrder]

We have 3 ultra low voltage 20w downlighters on 12v transformer in the bathroom. I have been fixing that switch that has fallen down and noticed the cable going to is only 1mm T&E, how much current would flow through this cable? The rest of the wiring upstairs circuit is wired in 1.5mm?

Am I right in thinking that 3 downlighters draw 10 amps? (120 / 12)? It seems far too high to me, the installation is about 9 years old and there is no signs of any indication the cable has overheated.

 

[ban-all-sheds]

how much current would flow through this cable?

About 300mA.

The rest of the wiring upstairs circuit is wired in 1.5mm?

It's not unknown for switch drops to be done in 1.0mm².

Am I right in thinking that 3 downlighters draw 10 amps? (120 / 12)?

120?? You said you had 3 x 20W. So 5A on the secondary side, but hardly anything on the primary.