Medium house doom

[simont]

Well, I expected to have to deal with some sort of homeowner's crisis at some point during my ownership of this house, but I hadn't really expected it to be quite this prompt.

It appears that all the electrical sockets downstairs stopped working yesterday evening, while I was out at a party. It further appears that this has nothing to do with the fusebox – none of the switches had tripped, and taking out the fuse for the defunct circuit and experimentally using it to power a working circuit proves that the fuse itself is fine.

Helpfully, the power came back on around the time I got home, and then went off again shortly afterwards, which caused a number of strange beeping noises as things started up again. I assumed this was the aftermath of a brief power cut and that everything would sort itself out by morning, and went to bed. But this morning it appears I was overoptimistic.

By means of long chains of my absurd surplus of mains splitters, I've managed to emergency-reactivate the fridge, freezer and network infrastructure using an upstairs power socket, but this is clearly untenable in even the medium term. So it looks as if I need an electrician, and ideally an emergency one who can come out today. Any readers of this got a recommendation?

Comments

[timeplease.livejournal.com]

I don't have recommendations for Cambridge electricians at the moment, unfortunately. Have you considered trying to find the fault yourself? It might be as simple as a loose connection. (Fault finding also involves working out how it ought to be working, which I find is very useful knowledge for any building I'm responsible for.)

There are some simple checks you can do with a multimeter. The circuit should be wired as a ring, so in the consumer unit you should see two live wires going into the fuse, two neutral wires coming from the same outer jackets as the two live wires, and two corresponding earth wires. (If you don't, your installation is probably old and bizarre and you should call an electrician.) With the main switch off (very important! And be aware that the cable leading to the main switch will still be live), and all appliances unplugged, you can disconnect the ring. Useful tests include:

• Measure the resistance between both 'live' ends of the ring; this should be low
• Measure the resistance between both 'neutral' ends of the ring; this should be low
• Measure the resistance between both 'earth' ends of the ring; this should be low

The next three tests should be done three times: once from one end of the ring, again from the other end, and finally using one wire from one end and one from the other.

• Measure the resistance between 'live' and 'neutral'; this should be high
• Measure the resistance between 'neutral' and 'earth'; this should be high
• Measure the resistance between 'live' and 'earth'; this should be high

Finally, connect one end of 'live' to one end of 'neutral'. Measure the resistance between the remaining 'live' and 'neutral'. This should be the sum of the 'live' and 'neutral' values you measured earlier (and they should be similar to each other).

These tests let you check that the ring main is still a ring (and doesn't have a break in the live, neutral or earth). Another test you can do to check the topology of the ring is to make up a mains plug with live connected through a fuse to neutral. Measure the resistance between live and neutral at each end of the ring with this plug in all the different sockets; this should enable you to work out the route the ring takes. (If you don't get figures that increase from one end and decrease from the other, that means someone has added a spur off the ring.)

When you have this information, you can make a more educated guess at where the fault might be. If all of these tests pass, then chances are something very weird is going on and it's time for an electrician.

[deborah_c]

I can't really help with the electrician, but I observe that this backs up my supposition that there's no such thing as "too many four-way tails" :-)

[simont]

That did occur to me, indeed; just as I'd finished saying I had lots of surplus ones, an emergency occurred that meant I needed to use a load of my spares in a hurry :-)

However, I still have quite a few left over.