I suggest a supply-side fuse has blown or one of the switch contacts is open circuit. if the 55V can be discounted as pick up, and I agree it probably can (or leaking round from the other live) then really you have supply off.
Chase further back to the thing supplying it to the point where the two lives part company, assuming thta is at 240 or so then chase in the normal way , or if the route is long with lots of access points, then open one in the middle and decide if the fault is in the 1st half or the 2nd half, and do divide and conquer that way. Given the coupling, de-energise both sides before doing any resistance checks, even just continuity buzzer many not appreciate partial mains, and there is a small risk of the mains coming back on suddenly in response to scratching about, if there it a part burnt contact.
Mike
I suggest a supply-side fuse has blown or one of the switch contacts is open circuit. if the 55V can be discounted as pick up, and I agree it probably can (or leaking round from the other live) then really you have supply off.
Chase further back to the thing supplying it to the point where the two lives part company, assuming thta is at 240 or so then chase in the normal way , or if the route is long with lots of access points, then open one in the middle and decide if the fault is in the 1st half or the 2nd half, and do divide and conquer that way. Given the coupling, de-energise both sides before doing any resistance checks, even just continuity buzzer many not appreciate partial mains, and there is a small risk of the mains coming back on suddenly in response to scratching about, if there it a part burnt contact.
Mike
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