ze tt

mcm · Apr 8, 2011

Does the ze for a tt system have to be under 200ohms.

Did a reading today and it was 210ohms, the area that the rod is situated is next to a drain. When I got their the drain was over flown.

Would you say that the rod needs moving and replacing due to the position and the 210 reading.

Thanks

SPARTYKUS · Apr 8, 2011

From what you've said, yes, move it. Or add another one! theoretical maximum Ze is 1667 Ohms but (in GN3 I think) it states as a guide over 200 is not good.

I'd normally be looking in the tens (17, 27, 54) not the hundreds.

What installation is it?

RWJ · Apr 8, 2011

As above ^^^^^^ Except if your NICEIC they seem to insist on below 100 ohms

Des 56 · Apr 8, 2011

We are given a maximum Ze for a 30 m/amp of 1667 ohms for a TT with a recomendation that it be under 200 ohms as you state,
210 ohms is not far off that recomended reading and I would consider that as acceptable
The resistance will vary depending on the weather,time of year,accuracy of test meter and in the end.it is an approximate reading of the resistance, which could well be lower if a earth rod resistance tester were used
Its location may well be a plus factor if the ground is being soaked

Many would accept readings that would be well in excess of your marginal result

RWJ · Apr 8, 2011

Did you pee on the rod????? It helps so I'm lead to believe!

SPARTYKUS · Apr 8, 2011

only if there's Stella in it.

RWJ · Apr 8, 2011

SPARTYKUS said:
only if there's Stella in it.

Friday afternoon would be ok then, if you worked with us

Penance · Apr 8, 2011

I'd consider trying another area and seeing what you get, over flowing drain would of dropped the reading I imagin. Could well be much worse when the area dries out.

That or ensure the drain is always blocked!

SPARTYKUS · Apr 8, 2011

RWJ said:
Friday afternoon would be ok then, if you worked with us

excellent!

A bit later for me here on the Shropshire / Staffs border, about 7:30 pm before the first glug of cancerous poison was imbibed.

RWJ · Apr 8, 2011

SPARTYKUS said:
excellent!

A bit later for me here on the Shropshire / Staffs border, about 7:30 pm before the first glug of cancerous poison was imbibed.

Naaaahhh too late for me... I've stop being paid by then!!!

Des 56 · Apr 8, 2011

Low figures are the aim,but its worth remembering,after every effort with urinating almost neat alcohol as failed (after having a gutsful of the rod and the beer)that the siuppliers earth electrode can be as much as 21 ohms,thats without the installation rod resistance and the earth conductor resistance

Low values and single figures are the exception rather than the norm, and is usually found because of a nearby Pme spike

GN3 states the earth loop test is permitted where there is an rcd, and resistances are relatively high, and precision is not required
Now that,with the other varying factors would encourage me to be content with 210 ohms
Either be content with that or get your drinking buddies to improve the readings