As above

Replaced the dimmer switch in dining room today with normal switch, now kitchen light won't work.

Fuse board has being reset & trip switch for area, everything else in kitchen works,

I pulled the wiring to get a better grasp, would I have pulled a wire from the kitchen switch in the process?

Are you sure you connected the same way? Possible cross connection with a switch loop circuit. Pull the kitchen switch from the wall box. You may have put a ground across a hot lead and tripped the breaker. What color wires did you use with the dimmer?

Whoever wired my house... Done a cowboy job.

All the wires are the same colour

Dimmer switch had two wires in port 3 & 1 wire to L1

I wired a normal switch the same way?

GB or continent I presume. We use 120 here, you use 240. 2 hot leads and no neutral. Still have a crossed or misplaced wire. I am not familiar with European wire systems, sorry

Could you tell us what country you're in? That might help. Wiring colors, hardware, etc. vary by country.

Be sure the two wires that connect at that port 3 are connected well together and to the switch.

One is the feed and the other would serve power to the remaining circuit.

FYI, UK and Europe does use 230 volts, and one leg, blue, is a grounded neutral.

Can you tell us if the wiring method is cable or conduit?