Earth leakage on sockets

[captaincaveman]

How did you get on Telectrix?

 

[rich.250]

It is tncs rich.250. Interesting point & one I haven't come across yet. I did do a polarity check on the incoming which I don't think showed anything wrong if memory serves. I will double check it when I go back tho. Where would the Neutral be lost? It would have to be between the incomer & neutral bar wouldn't it? cheers

If you loose a neutral it will normally be a connection on a overhead line.
The exact reason most DNOs will refuse to provide an earth now on overhead supplies.
Making nearly every new supply in my area TT!!

 

[captaincaveman]

.... SO, I managed to get back to have a look at it today.

I did dead testing on all circuits (which wasn't easy as the house has radials criss-crossing to sockets all over the place & hidden sockets in cupboards conceiled with clothes etc, ) and all the circuits tested ok. I did however find doing a alternative IR test (LN-E 250v) on the boiler resulted in <1Mohm but this was disconnected during other tests anyway.

I'm still getting up to 40V on the earth though. I observed it starts as 0 with all circuits dead and goes up steadily to 40V as each circuit is reenergised.

Any suggestions my good fellows?

 

[HandySparks]

I'm still getting up to 40V on the earth though. I observed it starts as 0 with all circuits dead and goes up steadily to 40V as each circuit is reenergised.

40V between which two points exactly?

 

[PEG]

Hi,when you say "on the boiler",do you mean the fixed wiring to the boiler,with boiler disconnected,or.....

Also,what were you measuring between,when you observed the increasing voltage to earth? Ta

 

[captaincaveman]

40V between which two points exactly?

Neutral & earth

 

[HandySparks]

Neutral & earth

Yes, but where? Distribution board, accessory, where?

 

[captaincaveman]

Yes, but where? Distribution board, accessory, where?

Sorry, I'm tired. ...Through all socket points tested & also using a voltage pen on the cpc teminal in the ccu

 

[HandySparks]

Sorry, I'm tired. ...Through all socket points tested & also using a voltage pen on the cpc teminal in the ccu

OK, are you measuring 40V between the DB earth bar and the neutral bar?

If so, then there's a high resistance somewhere in the cabling or components between those two bars and the supplier's head where they should be joined (as this is supposed to be TN-C-S).

 

[captaincaveman]

OK, are you measuring 40V between the DB earth bar and the neutral bar?

If so, then there's a high resistance somewhere in the cabling or components between those two bars and the supplier's head where they should be joined (as this is supposed to be TN-C-S).

As in the main switch, Neutral tail or main cut out connection?

 

[HandySparks]

As in the main switch, Neutral tail or main cut out connection?

Yes, if you have a significant voltage between N and E in the board when under load.

Worth checking for volt drop between incoming neutral terminal on main switch and neutral busbar.

I'd be checking tightness of terminals on main switch, link to neutral busbar, and anything else you can get at that isn't sealed up. Careful of any parts that aren't isolated, of course.

 

[PEG]

Hi,so you have a potential,between your probes,a very short distance from where those two points, are one and the same.

If you draw that scenario out,identifying the parts concerned,a clearer view of what may be occurring,will reveal itself :smug:

 

[rich.250]

I'm sticking by my previous conclusion.
I'm thinking if the bonding was disconnected you would have 230v between the bars as I don't think you have a neutral.
Turn the main switch off and do a l-n loop test on the incoming side.
That will soon tell you.
Rather than guessing at different voltages.

 

[captaincaveman]

Yes, if you have a significant voltage between N and E in the board when under load.

Worth checking for volt drop between incoming neutral terminal on main switch and neutral busbar.

I'd be checking tightness of terminals on main switch, link to neutral busbar, and anything else you can get at that isn't sealed up. Careful of any parts that aren't isolated, of course.

Cheers for that handysparks. I will investigate that. The whole installation is a bit of a joke so it wouldn't surprise me if it were the case of oversheared tails or untightened terminals (although I did check all the ones on the N bar & RCDs, I didn't check at the main switch).

Cheers again for everyones input. Appreciated

 

[HandySparks]

I'm sticking by my previous conclusion.
I'm thinking if the bonding was disconnected you would have 230v between the bars as I don't think you have a neutral.
Turn the main switch off and do a l-n loop test on the incoming side.
That will soon tell you.
Rather than guessing at different voltages.

If the supply neutral is lost, how would that give rise to a significant voltage between neutral and earth bars in the DB, given that they're joined at the head?