|
Posted to uk.d-i-y
|
|
|
Half of old house suddenly without power. Causes?
On 25/07/2019 23:07, wrote:
On Thursday, 25 July 2019 08:42:51 UTC+1, MM wrote:
On Wed, 24 Jul 2019 23:45:14 -0700 (PDT), tabbypurr wrote:
On Thursday, 25 July 2019 07:29:51 UTC+1, MM wrote:
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
Half the house without power means a whole CU dead, not one final circuit. They're called MCBs btw. If any one MCB tripped you'd only lose one circuit. You're presumably losing the whole CU, so it sounds like it has an RCD that's tripping. If that's the case, there are 2 tests to do. Insulation test each final circuit, then PAT test or insulation test all your appliances. Usually that will pinpoint the culprit.
Sometimes you can find the bad appliance by just insulation testing with a multimeter, one probe on L&N & the other on E plug pin - with the appliance unplugged of course. There should be no conduction there. So you may solve it with a £10 multimeter and an hour. Sometimes the fault is only picked up with high voltage testing.
A clear pic of the 'fusebox' would help
Thanks. I'll take a photo tomorrow. Maybe the electrician will be able
to squeeze him in again today, although yesterday the news was that
he's fully booked up today.
My own house is only 15 years old and, of course, has up-to-date
electrical equipment that one should expect in a 2004 build. My CU, in
the garage, has about 6 smaller MCBs and one larger MCB in the middle.
I suspect the larger one says RCD on it, and is therefore not an MCB. Photo should tell.
I rarely get any outage, although the MCBs are all super-sensitive. To
the point where when I was still using filament lamps, just the bulb
blowing would invariably trip the MCB for the relevant lighting
circut.
I gather from what I've been told that the electrical system in the
old house is quite ancient, as the electrican stated that after the
immediate fault has been rectified, at least temporarily, the whole CU
urgently requires replacing. Maybe the wiring, too, which would be an
enormous (and costly) job. It's a large house!
MM
Funny how peple always seem to recommend you give them money. We await the pics.
NT
There is a well established procedure for detecting which circuit is
causing an RCD to trip.
Viz with the RCD off switch off all mcb's.
Reset the RCD
Turn on each mcb in sequence to determine which circuit is causing the
RCD to trip.
Once identified investigate the 'faulty' circuit for line and neutral to
earth continuity and if necessary check insulation resistance.
Visual checks at accessories may then be required to establish wiring
condition.
|