Neutral switch question

[oldtimer]

East in that situation why did you not do the standard procedure and test between L-N , L-E, N-E I was called out 2 weeks ago and the guy said there is no power in the garage and his father inlaw who knows a little about electrics said there was no supply. So I did the above and found there was no neutral

 

[High Tower]

agree with hightower, neons are inaccurate, but so are volt sticks. yesterday i was called out to a non working PIR Floodlight. volt stick said "dead". suspicious, i then checked at source, still "dead". out then comes the fluke approved tester. shows 230v at source. turned out to be a duff lamp. and its not a mickey mouse volt stick, either, its a fluke. just proves-- check and check again. test tester on known "live" first.

That's it mate, that's why it's always said that volt sticks should never be used to test for dead, if used right they do have their place but only if used right! I do the same and only use mine for fault finding but I do the same I double check everything with my T5.

 

[EasT]

I don't think I would trust any equipment (other than my fingers ) to not give me a false negative. As before: are there any reports of neon drivers leading to electrocution, other than when they have been immersed in water etc.?

 

[Rikki Barrett]

Neon drivers light up on alot of things that are NOT live, thats why they cannot be trusted and should not be used for dead testing. Why rest ur life on a cheap and unreliable product? I agree with everyone else...............bin it. If you dont want to spend to much money, buy a steinel combi-check.

 

[Mikey]

@ darkwood - thanks for your reply,

also the neutral as we call it is created by tapping off the star point in the step/down transformer in the sub station and this is also the same point we get the earth from hence their is no voltage difference between neutral and earth

this is an area im trying hard to get my head around ^ im finding it a bit confusing.

There is 240v between live and neutral, but there is 0v between earth and neutral because they are connected together, and are sort of the same thing???

Also if neutral is 0 volts how does current flow through it, or is it that there is 240volts potential difference between the live and neutral that causes the current to flow in the first place??

I find it confusing because the neutral is described as the return of current but really we know that the electrons are just sort of moving back and forth????

Generally confused by the almighty neutral...

Again, any feedback greatly appreciated, this is driving me a bit bonkers.......

 

[oldtimer]

Think of it this way earth and neutral are both 0v potential but the earth is a protective circuit the neutral is the return path for the load both may be the same as you say but both do different jobs if you want to think of it that way.
Things do get a bit fuzzy in the modern house with plastic baths, sinks,pipes but rememember 50years ago + most installations got their main earth from the gas and or water supply pipe because they were metal so in a house then the pipework for the water and heating were all metal ie storage tank in the attic was tin so your installation was mechanically and electrically sound then they started putting in pastic tanks /sinks hence why the cross bonding. Now fast forward we have RCD protection and we no longer get our earth from water gas we no have to bond them as they enter the house

 

[Des 56]

A suppliers 3 phase transformer, secondary side, will have the ends of each of the 3 phases connected together,this is the star point
At that common point the phases are balanced,they each use the others for current flow,so at any given moment ,if you add up + current flow and _ current flow it will always be 0 at the common point,irrespective of the direction of that flow in the individual phase

Potential difference is what it says, a difference of potential, between one part of a possible circuit, and another part of a possible circuit

Between the outgoing points of each phase,there is 415 volt potential difference,because if you look at the circuit,there are 2 windings in series
Between any one of those phases and the common (or neutral) point,there is just the one winding which is 230 volt potential difference between that phase and the common point

The possible circuits are through the transformer secondary windings only at this time

If a connection is made from the common or neutral point of the transformer and with earth,"no current will" flow,there is no possible circuit,so no potential difference can exist,
The neutral or common point is now connected via an electrode to the ground


Taking one of the phase connections and a connection off that common/neutral point to a house will give a potential difference in that house of 230 volt between the phase and the common or neutral ponit

Practically speaking,when the circuits in the house are open,there will be no potential difference between the neutral and earth, because they will be connected at the star point at the suppliers transformer, so no potential difference exists

Once you get your head around the supply arrangements you will notice

Earth fault currents can get back to the transformer more easily via the neutral conductor of a TNC-s than it could via an earth rod,which uses the ground,that is called a TT earthing system Terra to Terra
In that TT system it means fault current has to travel down the rod through the earth and up the spike at the suppliers end, to the common connection(star point neutral), through the winding, and back again to the property ,

The difference between a Tnc-s supply and a TT supply, is that, earth fault currents can get back easier with a Tnc-s or TNs than a TT because the return is via a conductor ( sheath of an SWA or the neutral conductor) rather than via terra firma which does not conduct easily

 

[Mikey]

Thanks for the replies guys, cheers for taking the time. Its slowly starting to click