EMT connectors have always seemed a bit lame to me, in terms of CONTACT AREA, and there's all those long runs, hidden behind OLD plaster walls, subjected to who-knows-what kinds of abuse, errant nails, improper anchors, ig-nernt/expeditious "modifications", etc...

So... do you (breaker OFF) disconnect a receptacle neutral at the farthest extent of a conduit run, wire the neutral screw directly to the metal box w/ AWG12 copper, and plug in a 20A angle grinder?... then, while it's running, check voltage drop back at the panel? =:O

Or do you just ASSume it's lame, and pull a new green/bare GND wire?

... what say ye RKIs???

/exits thread

They are expensive, but if you are really worried you can purchase one.

Makeshift testing runs the risk of causing fires when trying to test grounds that turn out to be poor.

The electronic equipment uses very brief and slowly increasing low voltage waveforms with current monitoring to avoid creating heating if the current flow starts to limit as the voltage rises.

Mine cost over $1000.

hexus apparently missed the smilies... and sarcasm... or he went to check if his jumper cables are where he left them. :D

1. Ground Bond Tester.
2. Digital Low-Resistance Ohmmeter or DLRO.
3. Loop Impedance Tester (used in Europe, not readily available in US).
4. Ideal SureTest Circuit Analyzer - some models measure ground impedance.

#4 is probably the most affordable of these.

Turn off the power to the circuit, and verify near 0 volts AC between hot and neutral, and neutral and ground.

Switch the meter to ohms. Note the reading when the meter probes are shorted together (might be a little more than zero). Measure resistance from ground to neutral and subtract the value from shorted leads.

Note that if you get a hot to ground short, you have 120V divided by perhaps 0.1 ohm, so you get 1200 amps. That's good, because it trips the breaker fast, before much heat accumulates. If you have 0.5 ohm, that's 240 amps and the breaker will be slower (but still less than a second?), while 29 kw is heating up the bad connection. That could be dangerous. If you have 6 ohms and only get 20 amps, the breaker won't trip for hours and meanwhile you are dumping 2400 watts somewhere you don't want it and are guaranteed to start a fire.

Or any small ohm meter are not adequate.

The ability of the ground to carry current is what is important, and measuring resistance does not tell you if the ground path can current enough current to trip a breaker.

A correct bond tester should be used.
It applies a slowly rising voltage and measures the current that is flowing.
As soon as it hits the desired current it switches off to prevent excessive heating.
It also takes the voltage off if the current decreases at any time.

The most casual metalic path can produce a low resistance connection.
When a significant amount of current starts to flow the connection can simply act as a fuse and open, removing the ground path completely.

Before the bond testers became easily available, all sorts of equipment was used to verify ground quality.

A variac and an ammeter can be used.
You slowly turn up the variac until the desired current flows.
Since you will never be as fast as electronics at shutting the current off, it can create risk.

My waveform generator idea would have to drive a J-FET or similar power amplifier device. At that point I'm jury-rigging something when I could rent/borrow a proper version. Just needed to know it's name(s) in the trade.

Meanwhile, I have no tangible reason to doubt the integrity of any of the conduit, aside from some of it being 50+ years old, and the rest of it 25+ yrs. old. Even though ~200 yds. from Atlantic coast, NO visible rust anywhere, even j-boxes (yet), exterior or interior. (Apparently, a perpetual accumulation of latex paint IS salt spray-proof! ;')

If you really care about it, why not just run a grounding conductor?

Short answer: human nature + $$. On the one hand, running a separate GND appeals to my belt+suspenders side, but OTOH, it offends my thrifty+lazy side, lol.