Electrical wiring question

[Brian Ellis]

I don;t think that the live-neutral-earth/ground set-up is a 3-phase system. 3-wire, yes. Pretty sure in Europe (and the UK) we get 1-phase current normally.

Throughout Europe and even the UK, the distribution is 3 phase + neutral and each house on single phase uses 1 of the 3 phases + neutral, the earth being local.

Our house uses 3 phase 230/400 V for storage heating, but the individual storage heaters are single phase, as is the ordinary household use. We have 4 wires coming into the house and the earth is a whacking great copper spike hammered into the ground. The voltage between any phase and neutral is 230 V (star connection) and between phases is 400 V, but the latter is not used (delta connection).

If a house does not require 3-phase, only 2 wires enter, phase and neutral. As you go up a street, the first house is on phase 1, the second on phase 2, the third on phase 3. the fourth on phase 1 ...

In Switzerland, in order to reduce potential imbalance, cookers are always 3-phase. In the UK and here, they are single phase.

[Fat Tone]

OK, so I get that a small potential on the N could cause enough of a current on E to trip an ELCB. My question is having turned off the light switch and the trip for that ciruit, yet N is clearly not isolated, is our wiring up to code?

[Umfriend]

OK, so I get that a small potential on the N could cause enough of a current on E to trip an ELCB. My question is having turned off the light switch and the trip for that ciruit, yet N is clearly not isolated, is our wiring up to code?

I think it may be. Shorting N with E just closes another paralel circuit for all the other Lives that link to N.

@Brian E: You are right but that, IMHO, does not mean that your initial statement that the culprit was a 3-phase setup is correct.

[VJ]

There are two possibilities:

I know... but the projector puzzled me. OTOH, an old record player needs a earth connection even though it is none of those 2 possibilities. I figured the projector was something similar...

Throughout Europe and even the UK, the distribution is 3 phase + neutral and each house on single phase uses 1 of the 3 phases + neutral, the earth being local.

Yup... I have the 3 phase 400V connection for an induction cooking plate and for AC (it can also operate on 1 phase, but has 3 phase connection).

[Brian Ellis]

OK, so I get that a small potential on the N could cause enough of a current on E to trip an ELCB. My question is having turned off the light switch and the trip for that ciruit, yet N is clearly not isolated, is our wiring up to code?

Absolutely, according to the IET Wiring Regulations, all breakers, fuses, switches etc. must be only on the phase wire. The only double pole breaker is the Authority's ELCB/isolator in your meter box.

[Brian Ellis]

@Brian E: You are right but that, IMHO, does not mean that your initial statement that the culprit was a 3-phase setup is correct.

In this country, which follows the UK IET Wiring Regulations to the letter, it is easy to see as 99% of the cabling is overhead. In residential areas, the distribution is always 3 phase + neutral (4 wires). Most houses are fed with only 2 wires and it is easy to see that they are fed sequentially from the top, middle and bottom phase wires. Perhaps 10% or so of the houses, like ours, are fed with all 4 wires. The transformers have a 11 kV primary winding, fed with 3 wires in a delta connection and the 230/400 V 4 wire secondary is in a star connection.

[Umfriend]

Ah, I see now. It's as the load from different households is not balance, there will be potential (is that the word?) on the N that is shared among them?