High Ze reading on a tt install

[a.e.s]

Whats the best way to reduce a high reading on a new tt install, just had a reading of 240 ohms, though it has rained a lot since I have come home lol. is it just a case of sticking in another earth rod, the quality of the ground is not great for this and space for the rod is limited.

 

[scotsparky]

pritty much add a rod. If you can joint the rod onto existing and staight down if not an another rod but remember to leave at least the lenght of the rod as a space or you may get problems.

 

[ashrow]

Isn,t it a max of1667ohms allowed...................(please abuse me if im wrong so i can go and read up on the regs)

Ash

 

[scotsparky]

Ash

Have a read at reg 411.5 to tabel 41.5 and pay attention to Note 2 after that have a read at 542.2.2

 

[ashrow]

Ash

Have a read at reg 411.5 to tabel 41.5 and pay attention to Note 2 after that have a read at 542.2.2

Will do (seems i should keep my mouth shut whilst chewing my humble pie, i think i should lay of the stella, read posts,regs,others replies before jumping the gun)

Ash

 

[Gravid]

Hey up, I noticed the other week on a terraced house i was working on that the earth spike had

been installed right next to the neighbours spike, probably within 2 ft. I was wondering about the regs

on this, is there a minimum distance in this scenario? the houses where the type that ours mirrored next

doors. What problems might you encounter ? I'd forgot to look into this and this post reminded me,

cheers.

 

[scotsparky]

general rule is 1 electrode lenght apart. cant remember the exact problem but its to do with possible overlapping fault currents.

Something to do with a picture of a cow

 

[chocolate]

If two electrodes are too close together, and conncted to different installations, then technically there is a chance that a potential differnce greater than 50V could exist between the electrodes. Therefore, like the cow, the distance between front and hind legs could have a potential differnece enough to cause a current to flow through the cow.

Sounds like science fiction. But that's what they reckon - and I used to be a theoretical physicist !!!!!

 

[scotsparky]

no chocolate t can and has happened its to do with radiating voltages from the earth rod. (just checked) If the earth rods are to close the votages can overlap. Thats why the general rule is Minimum 1x the lenght of the rod.

 

[zupos40]

Whats the best way to reduce a high reading on a new tt install, just had a reading of 240 ohms, though it has rained a lot since I have come home lol. is it just a case of sticking in another earth rod, the quality of the ground is not great for this and space for the rod is limited.

You can try another rod in parrellal or add an extension to existing rod or you may have too consider a earth plate or gird, depending of soil type and height of water table, you say poor soil, is it chalky, clay, is it back fill with building rubble in.

Have you tested for soil conductivity etc, or ask for advice locally. web address may be of use

www.electro-specialties.com/.../Grounding%20Measurements.pdf

 

[electricAl]

Something to do with a picture of a cow

Love that

Actually, four legged creatures (big un`s like kye) are relevant in this, as they`ve been known to pick up on p.d.s in earth that we couldn`t (due to their `wheelbase`)
Just think how awesome they`d be if they learnt how to use a volt-meter
Great at spotting potential!

 

[steamboatwilly]

general rule is 1 electrode lenght apart. cant remember the exact problem but its to do with possible overlapping fault currents.

Something to do with a picture of a cow

Brilliant!!

 

[scotsparky]

well i was right and you knew what i ment.

 

[markythesparky]

If two electrodes are too close together, and conncted to different installations, then technically there is a chance that a potential differnce greater than 50V could exist between the electrodes. Therefore, like the cow, the distance between front and hind legs could have a potential differnece enough to cause a current to flow through the cow.

Sounds like science fiction. But that's what they reckon - and I used to be a theoretical physicist !!!!!

if the cow was a friesian and was chewing on the cud whilst being milked be a buxom blonde sitting on a wooden stool BUT who had a metal pail................. would the cow be white or brown?

 

[ajelec10]

Answer to you mark i think brown! not sure what were talking about mind,
The 1 elecrode appart stuff is some thing to do with a nice tec term i picked up from some where 'The sphere of influence' cool
AJ