How many 50 watt gu10 downlights can run from one light switch?

Fit a 20amp switch and you can have more than 12! Its worth advising the client that twelve 50w halogen GU10 spotlights will cost her around £180 a year in electricity to run and that they would save a fortune on energy costs by fitting LED lamps!

Well really you should be an electrician if you are working on for a client on a domestic system and entering into the realms of electrical design. But here goes 10A switches are the norm so the switches should not be a problem 12x50=600w which comes out around 2.6A this should be added to the total load on the rest of the circuit which if a 6A circuit ideally not exceed 1380w. These lamps are required to be installed using the correct fittings as required by building regulations and installed as per manufacturers instructions observing necessary clearances to negate fire risk.