On 16/11/2018 17:48, Pat Pending wrote:
On 13/11/2018 19:17, Roger Hayter wrote:
Pat Pending wrote:

Just put an electricity supply in to a shed at the bottom of the garden
- 4mm armoured cable to a separate CU in the shed. We have TT earthing,
so didn't use the cable earth and put in a 5/8" x 1m earth rod outside.
Measured the earth loop impedance, and I have 320 ohms - far too high
isn't it? Any suggestions?

Pardon my ignorance, but is there any reason you can't connect the house
TT earth to the shed via the cable?Â*Â* By all means use the new stake in
parallel.Â* An RCD at on or another end of the cable is probably needed
either way.


Update on this shed ELI problem. Following the suggestion here I did
export the house earth as well as leaving the new earth rod in circuit.
This reduced the reading to 109 ohms.

Still wondering why the shed TT earth was so high,

I wonder? Does the house earth benefit from other earth sources such as
copper/lead water pipes, or did you test the house earth rod on it's own.


--
Adam