A relative lives in a 300-year-old house. Yesterday he called to warn
that when I visit tomorrow (Friday) it's likely that roughly half the
house will still be without power. The other, smaller, half is
unaffected.

The electrician he called has so far not been able to diagnose the
cause of the problem. The half that is out is on a separate "fuse"
box. The other half of the house is unaffected. I write "fuse" in
quotes, but I understand that it does at least have the switches, not
old-fashioned fuse-wire fuses, although the equipment seems to be very
old.

The electrician, who is fully booked up today, tried for several hours
yesterday to pinpoint the cause and thought he had found it. But then
the "fuse" (i.e. switch) popped out again later in the afternoon.

Does anyone have any comments as to the cause? And how would an
electrician go about narrowing down the problem area? According to my
relative, the electrician knows what he's doing, i.e. isn't an
amateur.

How does one trace through all the wiring in the affected side,
especially given the age of the property?

Thanks.

MM