TT system earthing reading - Help ?

[Phil66]

Hi all,

What safe readings should I get for earthing a TT system in a domestic property ?

Thanks
Phil.

 

[telectrix]

if you mean Ze, anything up to 200ohms is considered normal. bear in mind, everything must be on RCD, and your max. Zs is 1667, the reaing can be improved by fitting a bigger rod and/or relocating the rod.

 

[Phil66]

Thanks.

Is ZE the same as Ra on the EIC Certificate. I am completing the Cert and not sure what reading to enter here ?

Thanks.

 

[telectrix]

i always enter the Ze reading. to do an accurate Ra requires additional kit and IMO is an unecessary excercise.

 

[nickblake]

Ra is the resistance of the earth Rod to ground Ze is the external loop , you can use either reading on the EIC , just going to add to what tel has said if your Ze reading is above 200 ohms the supply can be unstable so all readings should be below this

 

[Phil66]

Thanks Guys - been a great help.