Caravans - yes really - going round in circles....

[Marvo]

I think the 1667 ohm ceiling is purely safety related and derived from disconnect times in the case of a fault. I'd suggest it would be a professional approach to consider the functionality aspect of the earth as well which would involve looking how well it would perform for surge arrestors and noise suppressors etc in electronic equipment that might be plugged into the final circuits. On this occasion I'd be in the NICEC camp and striving for a stable sub 100ohm Ra or even lower if possible.

 

[Guest77]

I think the 1667 ohm ceiling is purely safety related and derived from disconnect times in the case of a fault. I'd suggest it would be a professional approach to consider the functionality aspect of the earth as well which would involve looking how well it would perform for surge arrestors and noise suppressors etc in electronic equipment that might be plugged into the final circuits. On this occasion I'd be in the NICEC camp and striving for a stable sub 100ohm Ra or even lower if possible.

Obviously a reading under 1 ohm is what we would like to achieve, the NICEIC do not write the regs book though and 200 ohms satisfactory to the book, personally I would not be anywhere near satisfied at that reading but the regs are the regs.

 

[GEOFF S]

UPDATE

So I did the work today - with 2 meters of 5/8 rod - 1233 ohms - 3 meters of 5/8 rod it came down to 168 ohms, 4 meters of 5/8 it came down to 113 ohms.

Added a 2nd rod at one of the vans (2 meters) and it didn't improve, and it was getting dark - so I'm going back next week with more rods and more couplers!

Sounds fine to me, i wouldnt get to hung up on acheiving a really low Ra, stable will do, by the way, the more you bang in the less effect it has of lowering the Ra, it all becomes a little fruitless.

Cheers

 

[Octopus]

UPDATE: A couple more rods and the reading is now 80 ohms.

So I gave up!

 

[Guest77]

so what is wrong with 80 ohms? obviously not the reading you would like but well within the limits to the regs Book

 

[GEOFF S]

UPDATE: A couple more rods and the reading is now 80 ohms.

So I gave up!

Perfectly fine, well done.

You can only work with the ground you have. Now if naturally the resistance is high then you have little chance of acheiving low values, remeber high values can be stable too and stable is the important bit.

Cheers

 

[telectrix]

the problem with the TT is that although each pitch is protected by a 30mA RCD, the distribution cable ( even if SWA) requires a RCD upfront to comply with disconnection times.

 

[GEOFF S]

the problem with the TT is that although each pitch is protected by a 30mA RCD, the distribution cable ( even if SWA) requires a RCD upfront to comply with disconnection times.

A problem in what sense Telectrix?

Cheers

 

[telectrix]

discrimination between RCDs.

 

[GEOFF S]

discrimination between RCDs.

Surley a time delayed will sort that issue out?

Cheers

 

[telectrix]

probably, not always.

 

[GEOFF S]

probably, not always.

Is "probably" not good enough, "not always" could you be more specific?

Cheers

 

[Geordie Spark]

did one a few weeks ago. 6 pitches on a gypsy site. 7 4ft' rods gave me a Zs at each pitch of 4 ohms.

So while you were nicking their wheels they were nicking your tools??

 

[Geordie Spark]

UPDATE: A couple more rods and the reading is now 80 ohms.

So I gave up!

A Spark using proper rods got 80 Ohms??

Me - a plumber (sort of) - got exactly that from a bit of 15mm copper tube hammered into the lawn!! :sailor:

 

[telectrix]

A Spark using proper rods got 80 Ohms??

Me - a plumber (sort of) - got exactly that from a bit of 15mm copper tube hammered into the lawn!! :sailor:

trust you to try and bypass your water meter. :juggle2:

 

[Geordie Spark]

trust you to try and bypass your water meter. :juggle2:

Funny you should say that. I've just had one fitted. It should save me about £100/year - and that's before I by-pass it! :joker:

 

[Geordie Spark]