Only half the lights working.

[diycharlie]

Switched kitchen lights on and "puff" sound, they went out. Pushed the appropriate fuse box button in and half the lights went on but a line of 3 didn't. There are a couple of connection boxes, (perhaps a transformer + another connection box of some kind) between them.
How can I mend it please?
Charlie.

 

[ban-all-sheds]

With the power off, check the wiring to the 3 which don't work - either there's a fault with that, or you have 2 transformers, and one has just given up the ghost.

 

[diycharlie]

How do I test the wiring and how do I know which transformer is broken?

 

[ban-all-sheds]

How do I test the wiring

Visually, initially - look for loose/broken connections.

and how do I know which transformer is broken?

You know which lights are not working....

 

[PrenticeBoyofDerry]

How do I test the wiring and how do I know which transformer is broken?

You could test for voltage at the primary side of the transformer (if you have transformers), if you are getting reading around 240V, but the light are not coming on, then there is good chance the tranny is deceased. Sometimes you may see burning on the secondary side cable/flex.
You could also try swapping the transformers over and see if it has the opposite effect on the lights.
When testing isolate the circuit prior to removing any covers, once covers have been removed and it looks safe to test, you can re energise circuit.
Test for voltage across line-neutral, line-earth. using an approved voltage indicator.
if no tranys, you need to be looking for loose connections and damaged cable, this could be at the lampholders.