Earth Loop Impedance Tester

[boater sam]

One of my old friends had a fabrications shed wired in pyro. He had moved things around a fair bit resulting in pyros all over the floor being trampled on and the steel wheels of the portable welder caused considerable damage.
Testing circuits showed bad earths and L to E and N leakage everywhere.
I got him to agree that a major refit was essential. Whilst fixing steel boxes and P clips I needed a 13A socket for power. I asked him if there was a socket I could use, but before he replied, I said I had found 4 in line on the wall. He shouted " No, don't use those, they are on the 3 phase"
Yes, he had wired a phase to each pin!
Happy days, and we all survived to tell the tales.

[Nick]

...Yes, he had wired a phase to each pin!

Similarly, when we moved into our house, it was a converted farm building - I had one of my staff, a qualified electrician check it over...

He went very quiet, went out to the garage and turned off the power - "I may be some time", he said...

Being a farm building, (an oast) we had 3 phase 100A coming in. In the kitchen, he found twin light switches with two phases, the oven on another phase different to the hob next to it. etc. etc.

It was a potential death trap.

Eventually we completely rebuilt the place - all to current regs now...

[ppppenguin]

In the kitchen, he found twin light switches with two phases, the oven on another phase different to the hob next to it. etc. etc.

It would be unusual to have 3 phase in a domestic environment and it wouldn't be common to have multiple phases in one room. But the wiring regulations allow this, subject to appropriate labelling. The hazard is to an installer rather than a user. For example when working on those light switches they need to be aware that more than one circuit needs to be isolated and that there's 400V between terminals in one enclosure.