Earth electrode testing

[sparkiejohn]

Just discovered this forum through google!
I have a question as regards to testing an earth spike.
I have completed a new installation but would like to test the earth electrode resistance before the supply authority comes to connect the power/metering etc.
The tester I am using need to be connected to a 240volt supply to operate.
I took an extension lead from the next door neighbours house. (The two neighbours get on well!)
I connected my tester to the supply in the lead. Disconnected the 16mm earth cable to the spike and tested it.
I am getting a reading of 280 ohms.
Then I thought about it that either I will have to fit another earth spike to lower the resistance, or because I have took a supply through an extension lead from the house next door, I am getting a false reading.
Any suggestions ideas are appreciated!
Thanks!

 

[RF Lighting]

You will need to either extend the rod and rive it in deeper, or install additional rod(s) and connect them together.

As this is a new supply, was PME not available?

 

[sparkiejohn]

Thanks for the reply RF.
It's a domestic installation and the supply authority have said TT supply only.
The property is located in a rural area (Don't know if thats the reason?)
Wasn't sure wether the it was the earth spike at fault or if its was down to connecting a supply through an extension lead that was giving me a false reading?
As far as I am aware the supply authority can refuse to connect if the earth is insufficient.

 

[RF Lighting]

Yeah, it will be because it is rural. Most of the rural networks have been upgraded in my area, but that doesn't really help you

You just need to put on another rod and see what difference that makes. Have you used the type with a threaded end?

 

[sparkiejohn]

Thanks again RF.
I will add another spike and re-test.
I am just using the standard 1 metre earth rod.
Haven't seen the screw type rod yet.

 

[Spark123]

http://www.tlc-direct.co.uk/Main_Index/Earthing_Index/Earthing/index.html

 

[toptip123]

I would make sure an RCD or RCBO are used to pick up any earth faults. As earth spikes readings will vary depending on how wet the ground is and come summers!

 

[Taylortwocities]

If you use multiple earth spikes you must keep a degree of separation between them or you don't get the additional benefit that you had hoped for.

There's a good Wiring Matters article from the good old IEE/IET.
Read all about it here:
http://www.theiet.org/publishing/wiring-regulations/mag/2006/21-ttsystem.cfm?type=pdf