Question about tesing earth.

[tebreak]

Can anyone tell me how i can test an earth connection using a multimeter.
can do a continuity test , but not sure how to test for resistance.
I was thinking of testing the connections on the MET.

is there an accepable amount of resistance

 

[securespark]

The main tests are resistance, continuity & Ze for the earthing conductor.

Also connected to the MET may be PEB's to gas and water pipes etc...

These need to have a resistance value not exceeding 0.05 Ohms.

You cannot do Ze with your MM.

Which model have you got?

You may be able to do resistance, but whether it would be accurate depends.

 

[Chri5]

Multi meter range, resist- ohms. Set and put the probes together should be a zero value.

Then make a wander lead, any wire and fix that to one of the probes. Test the wire and note the reading.

Then put one side (the wander lead side) on the MET and go forth with the meter and test the earths.

The meter will then give continuity via MET- Wander lead- one side of the meter- other side of the meter- path back to MET via the earth being tested.

The reading is false beacuse it will include the wander lead and probe lead resist, so deduct that figure (tested in line two) from your reading.

Most should be low readings in ohms, sometimes you may need to remove the earth to be tested if you suspect parallel paths.

 

[ricicle]

Do not disconnect any of the circuit protective conductors, main protective bonds or the earthing conductor while the installation is energised !

 

[Taylortwocities]

Which model have you got?

.

This is a key point.

You will need what is called a "low ohm" meter to measure 0.05ohms. General purpose multimeters do not have that level of accurancy. You will need a continuity tester that is designed for this purpose, as is calibrated.

Or a multi-function "17th Edition Tester"
(or a 16th, 15th 14th edition one!)