My son installed a new Stoves electric oven a couple of months
back. Although the oven light and fan came on, the clock
display didn't and neither would the elements. On taking the back
off I found a wire (with spade type socket) had come adrift
from the neutral of mains input connector block. It was a relatively
thin wire going to the control/clock unit. Tightened up the
connector a bit, put it all back together and the oven worked
Yesterday got a call saying the oven had stopped working,
same symptoms as before. He took the back off and checked
the wire, still in place. Mentioned that earlier in the day he'd
got a "tingle" off the oven. The oven has it's own mcb, but no
rcd protection. Told him to isolate it and wait for dad!
Called in today, isolator switch on the wall was off, so before
going further I turned it on and used a multimeter on ac volts
range to check between the oven casing and the adjacent sink tap
(plumbed in copper, bonded to earth). 230 volts!! (he
went and put some shoes on at that point!). He said he'd
loosened the isolator from the wall while doing some grouting,
so flicked off the mcb and unscrewed the isolator switch.
Earth conductor to oven floating loose. Put it all back, switched
everything on, oven clock/timer now working and no voltage
on the casing. Oven now works ok, but I'm still wondering
why a disconnected earth would result in 230v on the casing.
In retrospect, maybe I should have put on some sort of "load"
when doing the voltage check, I suspect that the voltage is
coming from the "neutral side" of a highish impedance load,
maybe the electronic clock/timer, but this still seems wrong to
- posted 13 years ago