Triple phase electric supply in a house

[JohnW2]

I would say over 99% of houses have a switch plate fed from two circuits (single phase). There was a time when a note was placed inside the switch box, saying something about the accessory being fed from more than one circuit, and to isolate disconnect more than one fuse or circuit breaker.

Exactly my point. Common (and clearly 'accepted') though that is (at least, since split upstairs/downstairs lighting circuits came into vogue), I would say that it is only fractionally less potentially dangerous (particularly for the 'DIY meddler' you cited) than having two different phases on the same plate.

Kind Regards, John

 

[sparkwright]

The difference between 230 v and 400 v is hardly fractional though!

 

[JohnW2]

The difference between 230 v and 400 v is hardly fractional though!

True, at least numerically - but I'm not sure that it necessarily makes as much difference as you might imagine - after all, I presume that no-one is suggesting that a 230V shock is even remotely 'safe'!

Kind Regards, John

 

[AndyPRK]

The difference between 230 v and 400 v is hardly fractional though!

Phase to ground is still 230V though.

So they will only get 400V if they touch two live phases.

 

[sparkwright]

People have died though, in situations where they've been in contact with two phases.

I believe there was a case with a metal ceiling grid and two light circuits on different phases.

 

[sparkwright]

The difference between 230 v and 400 v is hardly fractional though!

Phase to ground is still 230V though.

So they will only get 400V if they touch two live phases.

Exactly.

 

[JohnW2]

People have died though, in situations where they've been in contact with two phases.

I'm sure that no-one is suggesting that 400V shocks can't be fatal - but plenty of people have also died as a result of being in contact with one phase (plus earth or neutral).

Even if one wanted to, I doubt whether one could find any useful statistics on the relative risk (of fatality) in two situations, since I suspect that one would be pretty hard pressed to find many cases of phase-to-phase shocks.

Kind Regards, John