ECN Forum Forums General Topics of the Trade Non-US Electrical Systems & Trades Mcb's used as functional switches?

Master switch is common in many large common areas, have seen them particularly in teaching labs and classrooms. Usually i have wired them as a switch or mushroom button feeding a contactor on the load side of the c/b.

I would suggest that use of a c/b as a switch may lead to contact welding, dependant on load or more likely internal failure causing an open circuit.