Half of old house suddenly without power. Causes?

[Tufnell Park]

That's only if you are unlucky, most of the time it works!

[MM]

[snip]

Right-o, I'm back from visiting and here is the pic of said consumer unit:

This was installed in 1996.

Meanwhile, the electrician found the fault. It was burnt insulation on the cables to the halogen ceiling light in the upstairs bathroom which caused the wires to short.

Thanks all for the handy tips!

MM

[MM]

Actually, my relative *did* run a temporary extension lead to the kitchen fridge. The freezer in the garage was unaffected. For a pic of the consumer unit, see here:

The CU was installed in 1996. Relative will have it replaced asap. Maybe (some of) the house wiring, too. It'll be a massive job, because the house was originally built 300 years ago and is huge.

MM

[MM]

This is a new one for me. *I* have two UPSs, one for each PC. They are both by APC. I just plug 'em into the mains.

MM

[tabbypurr]

Very blurry. Looks like you have no RCD there.

NT

[jrwalliker]

Just like everyone else does. However, if the mains fails the two UPSs will be outputting asynchronously generated waveforms, so some of the time the outputs will almost certainly be out of phase with each other and the relative peak voltages will be even higher than with two phases from a three-phase mains supply. In other words, your situation with two UPSs is potentially more "dangerous" than running an extension lead from one phase of a three-phase mains supply to an area with a different phase.

In reality, there is no problem, just as there is no problem with having different phases of a three-phase supply near each other. This is because each live connection is insulated and to suffer the effects of the higher voltage difference there would have to be multiple simultaneous insulation failures.

(I know that three phase mains will deliver much higher fault currents in a phase to phase fault than UPSs, but for that to happen there still need to be multiple simultaneous insulation failures.)

John