naked ladies!!!!!

[VoltzElectrical]

no, actually, no real naked ladies, but

I done a EICR or PIR actually on an old house with apparent TT set up for earthing. 6mm earth cable coming up from the door step to the 3036 board. I disconnect the earth cable and do a Ze. Reading? - 0.11!!!!!!! Test between Live and neutral, same reading.

Can't see where connection made between neutral and earth. Any suggestions?

 

[SYKRAPS]

appreciate the advice, but a little impracticable TBH. Not My House and given the readings, not justifiable to start smashing about a customers residence for what? A better reading! FFs I'm after advice about why the readings are so good!

I get what you mean but it is not beyond the realms of possibility that the rod can acheive the 0.11 ohms so you may be searching for nothing, that is why I would want to test the rod directly with no existing cable connected to rule this out no matter how unlikely

 

[SYKRAPS]

he has done syk...
its just strange (but not impossible) to be getting .11 on a TT....
the same on Zpe & Zpn however can only really mean one thing

The way I read it was that the cable leading to the rod has been tested and because it is not accessible it may IMO be connected to ground somewhere over its length before it reached the rod

 

[GLENNSPARK]

but it still wouldn`t explain the similar values of Z

 

[VoltzElectrical]

The way I read it was that the cable leading to the rod has been tested and because it is not accessible it may IMO be connected to ground somewhere over its length before it reached the rod

Anything is possible, I was asking if anybody has seen anything LIKE this, and if so, WHAT the explanation WAS.

Simple. TNC-s readings on apparent TT supply????????????

 

[VoltzElectrical]

but it still wouldn`t explain the similar values of Z

Exactly. Apparent TT supply but same readings L-N as L-E. ).11 Ohms.

Where can the earth be connected to neutral?? No connection evident on sheath or from service head.

 

[GLENNSPARK]

Exactly. Apparent TT supply but same readings L-N as L-E. ).11 Ohms.

Where can the earth be connected to neutral?? No connection evident on sheath or from service head.

well....you`v verified theres TT present....
you may have to go with that...
not ideal but...

 

[SYKRAPS]

Ah ok so you have a very low earth loop at origin for TT infact more than acceptable for a TN system and you are taking a reading from a cable that you 'pressume' runs directly to the earth rod.

My first thought would be that the earth cable to the rod calls to a service pipe over its route from origin to rod, this service pipe is common with the neighbouring property that has been PME'd hence the low reading.

I would want to take presumption out of the equation and test the rod direct for the property and draw conclusion from that reading, if this reading is higher then the cut out or supply cable has been doctor'd in some way.

My experience with regards to this scenario has always been a parallel earth from a service pipe, was it not practice once over (before my time and something that I have never done btw) to use incoming water mains as earth rods?

 

[guest119]

is the house a semi or terrace ?
if so check next door.
i'd be reluctant to record the earthing arrangment as TT without locating the rod first.

Yea semi?
Misleading title of thread:biggrin5:

 

[SYKRAPS]

Exactly. Apparent TT supply but same readings L-N as L-E. ).11 Ohms.

Where can the earth be connected to neutral?? No connection evident on sheath or from service head.

At a neighbouring property PME

 

[GLENNSPARK]

Ah ok so you have a very low earth loop at origin for TT infact more than acceptable for a TN system and you are taking a reading from a cable that you 'pressume' runs directly to the earth rod.

My first thought would be that the earth cable to the rod calls to a service pipe over its route from origin to rod, this service pipe is common with the neighbouring property that has been PME'd hence the low reading.

I would want to take presumption out of the equation and test the rod direct for the property and draw conclusion from that reading, if this reading is higher then the cut out or supply cable has been doctor'd in some way.

My experience with regards to this scenario has always been a parallel earth from a service pipe, was it not practice once over (before my time and something that I have never done btw) to use incoming water mains as earth rods?[/QUOTE]yep...once upon a time...
in hindsight the post i made at #36 was a poor one....
it needs verifying does this....either way...

 

[GLENNSPARK]

the proof of the pudding would be to gain access next door....see what the arrangements are there....

 

[KevinS]

Voltz, you t**t,
getting me all excited, especially this time on a Saturday night, especially after a few beers
sorry but your off the christmas card list!

 

[GLENNSPARK]

Voltz, you t**t,
getting me all excited, especially this time on a Saturday night, especially after a few beers
sorry but your off the christmas card list!

is that better...

 

[Engineer54]

God forbid that an electrician has actually installed a TT system properly!! lol!! Though i doubt that, if he has only connected a 6mm main earthing conductor to a rod giving a 0.11 Ra value!!

How old is this semi detached house??

 

[Richard Burns]

It is possible, but unlikely, that you have a very good TT earthing system that happens to match the L-N impedance.

Other options that occur to me is that if the concrete path extends to the left and the gas incomer is metal then a low impedance would be gained from a connection to the gas pipe (although not permitted).

Another possibility is if the earthing conductor extends to another house with PME earthing.
Or perhaps to a DNO earthing point from the overhead supports!!

Really check back later and see if it has changed in which case further investigation required, otherwise just indicate that the earth rod is inaccessible but results OK.