On 19/11/2018 10:40, John Rumm wrote:
On 19/11/2018 08:50, Pat Pending wrote:
On 18/11/2018 19:45, ARW wrote:
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.
No, I didn't test the earth rod on its own. As I said in my first post
I don't have the tester to do that. The house doesn't have gas and the
water pipes - coming into the house at any rate - are plastic so I am
assuming that there are no parallel paths to earth and that the
readings I get at a socket are fairly accurate.
I take it you are testing with a plug in earth loop tester?
If so you can always temporarily disconnect any equipotential bonding
wires at the main earthing terminal while doing the test if needs be for
more accurate results.
If you wanted to test the rod in isolation, there is a method for doing
so without any special test gear described he
http://wiki.diyfaq.org.uk/index.php/...ode_resistance
OOI, is there any reason I can't use the neutral incomer as an
alternative to "Supplier's main earthing terminal"?
If there is a small residual voltage on the neutral, swapping the
transformer phase and taking the average of two measurements would help
but should be a fraction of 24V.