No earth - is it a TT looks like PME to me

[leolec]

Just want to bounch this off others,

1980's house built in rural village, other houses in the village have PME supplies and test out with Ze of around 3.5. Did a quick test when I got there on a ring and getting Zs of 10.45 on further investigation theres no main earth so thought well is this TT if so no rod - can't be - main incomer comes out of the ground looks just like other PME supplies light grey 100A fuse box SWA going in - did the installer just miss the earth off? seems strange - 10mm Main Bonding all there.

 

[cagedanimal2010]

others test at 3.5??
10.45?
sounds like tt.

danny

 

[leolec]

Would a TT system give a Ze of 9 or 10 ohms? I thought they normally gave more like 70 up

 

[telectrix]

3.5 is crap for PME anyway. could it be no earth and the reading is from the main bonding to gas and water? is there an earth terminal taken off the cut-out? have you checked in the |CU to see if there is an earth connected ( apart from the bonding)?

 

[leolec]

Thats what I've been thinking - there's no earth to the cut-out the cut-out goes straight to the meter and then to the cu, theres main bonding I didn't get time to test them but I'm assuming gas and water so my thought was I'm getting 10ohms from line to gas or water pipe

 

[telectrix]

think it's time to ring DNO.

 

[sjm]

Ring DNO for a PME check. Ze for PME should be 0.35 ohms or less. 0r below 0.8 ohms if it's TNS.

 

[leolec]

Thanks everyone,

It's an underground TT -finally found the rod, the earth cable was wrapped in condu and the rod six inches below soil level - 10ohms - great.

 

[aptsys]

Don't forget when testing Ze you should have all bonding removed. 10 ohms sounds like you still had gas or water bonds attached and possibly picking up an earth from next door through this.

 

[leolec]

Better go and retest I think.

But picking up on that point then, so this house is TT with earth rod say 70 ohms and next door is say PME with 0.35 ohms, then the first house finds earth through second house rather than the rod?