not_shocked_yet
Well-known member
[SIZE=10pt]Hi Everyone,[/SIZE]
[SIZE=10pt]Please read ALL of the post below before contributing as the fault is unusual (for me, newly qualified).
My client called me out because turning on the lights in her (2009) converted stable block tripped the RCD (this is the main switch in the stable DB). Trying to re-set the rcd three times or so (it kept tripping) would then trip the (old) single RCD in the main house. To be clear, the house RCD is between the meter and the CCU.[/SIZE]
Turning on the CB's in the stable block one at a time determined that one of the lighting circuits was causing the trip.
Anyway, whilst performing safe isolation in the stable (with a Kewtech KT64DL) with the supply turned off at the main CCU in the house I recorded a <25v across Line and Neutral but 65V across Earth and Line and Earth and Neutral.
Removing the L, N and E at the CB in the main house for the supply to the stable DB recorded a normal reading of <25V across all L.N and E combinations.
To be clear the DB at the stable is approximately 250 feet from the main CCU. I don't know yet what the cable is to the building (thinking it should be armoured) if it is joined somewhere en-route (which I doubt) otherwise it looks like 6mm or similar twin and 2.5mm earth (it's the red and black variety) - thats what is showing at the CCU and the DB anyway.
Testing voltage at the main switch at the CCU: With the main switch on I recorded 245v across L and N supply and <25V across E and N and E and L. HOWEVER with the main switch off I recorded <25V between L and N and 165V across E and N and E and L.
This is a TT system.
I used a 2 pole voltage tester to also test between E and L,N but still had a reading of over 50V.
Am I looking at a ghost voltage causing the readings? Is the house safe - it seems to be when the system is energised? Could there be a potential difference between bonding and supplementary bonding if the power went off?
The house is thatched and had a periodic inspection 6 months ago (not the stable however) for insurance purposes. No problems were reported at the time to the owner.
I ran an earth fault loop impedance test at CCU and recorded 30.5 ohms.
Hoping this is just a ghost voltage, any thoughts are most welcome.
Many thanks in advance!
[SIZE=10pt]Please read ALL of the post below before contributing as the fault is unusual (for me, newly qualified).
My client called me out because turning on the lights in her (2009) converted stable block tripped the RCD (this is the main switch in the stable DB). Trying to re-set the rcd three times or so (it kept tripping) would then trip the (old) single RCD in the main house. To be clear, the house RCD is between the meter and the CCU.[/SIZE]
Turning on the CB's in the stable block one at a time determined that one of the lighting circuits was causing the trip.
Anyway, whilst performing safe isolation in the stable (with a Kewtech KT64DL) with the supply turned off at the main CCU in the house I recorded a <25v across Line and Neutral but 65V across Earth and Line and Earth and Neutral.
Removing the L, N and E at the CB in the main house for the supply to the stable DB recorded a normal reading of <25V across all L.N and E combinations.
To be clear the DB at the stable is approximately 250 feet from the main CCU. I don't know yet what the cable is to the building (thinking it should be armoured) if it is joined somewhere en-route (which I doubt) otherwise it looks like 6mm or similar twin and 2.5mm earth (it's the red and black variety) - thats what is showing at the CCU and the DB anyway.
Testing voltage at the main switch at the CCU: With the main switch on I recorded 245v across L and N supply and <25V across E and N and E and L. HOWEVER with the main switch off I recorded <25V between L and N and 165V across E and N and E and L.
This is a TT system.
I used a 2 pole voltage tester to also test between E and L,N but still had a reading of over 50V.
Am I looking at a ghost voltage causing the readings? Is the house safe - it seems to be when the system is energised? Could there be a potential difference between bonding and supplementary bonding if the power went off?
The house is thatched and had a periodic inspection 6 months ago (not the stable however) for insurance purposes. No problems were reported at the time to the owner.
I ran an earth fault loop impedance test at CCU and recorded 30.5 ohms.
Hoping this is just a ghost voltage, any thoughts are most welcome.
Many thanks in advance!
