Ihave only very basic electrical knowledge but hope you can help. A bulb blew in the upstairs bathroom this am and tripped the mcb, I replaced the bulb and reset the mcb but now have no lights at all upstairs. All other circuits are ok, the only upstairs light is the landing which is on a dual switch at the bottom of the stairs, however that dosent work when the mcb is off for the upstairs circuit. Is it likely to be a faulty mcb? Any suggestions welcome.