Is there a way to test for current via the hot only? For example, could you test the black wire only, or do you have to have neutral or ground to test?

You can test current by the hot only, or the neutral only, clip Amprobe around wire is common for AC voltages, For DC, Voltmeter set to amps and inline with hot or ground connection. About 10 years ago, they came out with an amprobe for DC Circuits.
Voltage Test needs BOTH, hot and neutral(or hot and ground), or 2 hots.

Always measure the hot to determine load.

Only measure the neutral or ground for special troubleshooting circumstances.

They make an insturment that will check for voltage in a hot wire only but it is very expensive, too much for just one test.

I have one but don't remember the manafacture or number but if you want me to check it out I will.

Hey, I have a cheap < $50 Sears gizmo that claims to sense both. Non-contact.

So you can test for current (amps) but not voltage. I don't suppose you can get "power" from hot only? Ah, who am I kidding, if we could get power from one wire, that'd be how we'd be doing it I suppose.

Hey there are technologies being developed to transmit power wirelessly and technologies that use energy harvesting to power electronics. Since the act of mechanically moving a switch can create a small amount of energy, that mechanical energy is "harvested" as electrical energy. This allows wireless control with no batteries at the transmitting end.

What?


So you can test for current (amps) but not voltage.


You originally asked;


Is there a way to test for current via the hot only?

Are you know asking how to test voltage?

Confusing the experts here.

Tk:

This is the instrument that I have. DVA30 - Non-contact AC Voltage and Current Detector (http://www.extech.com/instruments/product.asp?catid=31&prodid=128)

OK, I read the manual.

May just be me, but I took "testing" for current meaning to actually measure the current flow, which would provide a numerical readout of the actual current flow,such as 10.2 amps, etc.

All this does is indicate voltage on hot wire, and gives an indication of current flow, but does not give actual measurement.


I don't like these proximity testers for voltage for professional use, but I see an advantage to DIY'ers. To help them detect voltage in a safe, non-contact fashion, as long as all serious precautions are taken.

I told the story of one of my guys using these, checked a known live circuit to test the tester, and then used it on the wire to be worked on a few minutes later.

It tested dead, my guy almost became the same, as the wire was very much alive.

And only indicating current flow without knowing how much... I don't get the benefit.