water main bonding conductor

[silver surfer]

Got a job where the incoming water main has got 50mm bond back to the nearest stantion as in building structure upright, which i suppose is a pretty decent earth
But how do i test the continuity back to the MET? (less than or equal to 0.05 ohm) etc, which is about 150 metres away.

 

[MarkieSparkie]

Got a job where the incoming water main has got 50mm bond back to the nearest stantion as in building structure upright, which i suppose is a pretty decent earth
But how do i test the continuity back to the MET? (less than or equal to 0.05 ohm) etc, which is about 150 metres away.

Continuity test method 2 using a long lead (>150m), two 100m reels of 4mm[SUP]2[/SUP] earth cable joined in series, or similar would do nicely. Ensure safe isolation of the supply. Connect one end of the long lead to the MET, connect the other end to one of your Low resistance Ohmmeter leads via a croc-clip. Null the tester and long lead. Measure the continuity by contacting the water service pipe ( NOT the pipe clip or the structural steel) with the other probe and check reading is <0.05 ohms. Because there isn't a continuous main protective bonding conductor back to the MET that can be disconnected at one end and measured, inevitably your measurement will include parallel paths. Even if you were to disconnect the structural steel main protective bonding conductor at the MET and measure from that conductor end to the water service pipe the measurement will still include some structural steel parallel paths, there is little to gained by doing so. This is common in industrial and commercial situations.