Integrity of EGC

[Ponchik]

How can we check the integrity of an EGC, whether a wire type or a conduit type.

We can't, can we?

 

[JFletcher]

By resistance? If you have a receptacle in EMT 100' away from the panel that supplies it, it should have roughly x resistance from box->conduit>fittings...>panel, and y resistance from yoke/grounding pin>grounding wire>ground bar in panel. I dont have numbers handy but would imagine numbers in the tenths of an ohm for such a run. 1 ohm may be fine, 25 might indicate corroded conduit, infinite would be a break in the run or the wire.

 

[al hildenbrand]

How can we check the integrity of an EGC, whether a wire type or a conduit type.

We can't, can we?

I think it would be fairly easy in a building that is largely constructed of non-conductive materials like wood framing. Start off by laying out the length of insulated wire that one needs to extend the probe length of an Ohm meter from end to end of the EGC, and then measure the resistance of that insulated wire. Connect one end of the insulated wire solidly at one end of the EGC path to be tested, and connect the other end to one of the Ohm meter probes. Connect the other probe to the other end of the EGC to be tested, take a resistance measurement and deduct the insulated wire resistance.

 

[don_resqcapt19]

You need something better than just a DMM....you need something that will flow some current through the EGC.

 

[mivey]

Loop impedance test:


http://ecmweb.com/cee-news-archive/ac-loop-impedance-testing

 

[Ponchik]

You need something better than just a DMM....you need something that will flow some current through the EGC.

Please explain more.

I am assuming if I connect a load between the energized conductor and the EGC and if the EGC is not an effective path then I should have a voltage drop??

 

[mivey]

They make devices for that. Gar has probably posted more than one example of an impedance test routine.