Hi All,
Am considering purchasing one of those units but am unsure what to expect from it.
Can one simply clamp the jaws around any wire and get a reading on amps passing though and perhaps volts as well?
What if you clamp it around conduit or BX flex cable? Does that work?
The reason I’m asking is that I purchased an old building recently with a lot of wiring and would like to use this to figure out what hot and what’s not.
Thanks,
Tom
Replies
Note: I am not an electrician but I have had some experience with clamp-ons
To use a clamp-on you must clamp it around only one of the circuits conductors, not a pair of conductors such as a lamp cord. The purpose of this instrument is to indicate current flow. I never saw one that would give you a voltage reading, but things keep changing. An ampmeter will not indicate if a wire is hot (powered) if the loads it powers is turned off. A zero amp reading means that no current is flowing or the current draw is lower than the detectable level of the instrument.
I think what you need is a voltmeter and a good knowledge of how to use it. If you are unsure don't mess with electricity, it has a way of showing you what power really means. A friend of mine, a licensed electrician is now know as "Neon Leon" after his almost deadly run-in with 480 volts.
Irondog,
I second oldlou's advice. Get a digital multimeter and learn how to use it.
There is an "all-in-one" probe that indicates both approximate voltage and current. It's sort of a fat non-contact voltage tester. Made by Amprobe, model K-1. It's accuracy is very dependent on the orientation of the tip to the cable (it will work on intact romex or cords), so I use it more as a screening tool. If I recall right, it costs about $40.
You can't go wrong with the Fluke 112 for a solid, mid-featured multimeter (about $125). I'm not a big fan of cheap meters. A false reading can drive you nuts, waste time, maybe kill you. If you decide to get an inexpensive meter, buy some good leads and probes.
If you can wait for the October issue of FH, there's going to be a write up on basic electrical testers in the "What's the Difference" column. There are a couple in the $80 range that actually might be more useful to you than a multimeter.
Cliff
Irondog,
The other reply is right on about the ampmeter. It only measures amps and only when wrapped around one of the conductores.
What you seem to need is called a "Tick tester". These cost abou $10 and are readily available whereever electrical stuff is sold [even Home Depot]. They're about the size of a cigar and you touch the tip to a wire - no need to strip insulation - and it will chirp and flash indicating AC voltage. Sometimes it will pick up neutrals too and in a crowded box it may be misleading but better be safe than sorry.
Onetime I was going to add some wires to circuit #39 and I asked the foreman to shut of that circuit and he said he did. But I checked it with my little tic-tracker and it went off. It turned out that there were two panels supplying that room and he had turned the wrong #39 breaker off.
-Peter
As an elect/comp tech I have to strongly suggust that you use only fluke or other high quality equip. The other posts are correct in steering you away from clamp an amp probes, they work extremely well for their designed purpose; However, you want it for a different purpose. I use a fluke cigar to check wires, if the insulation is good you might have to touch the wire sheath but they are very reliable and keep your hair unsinged.
Thanks to everyone for your thoughtful replies!
It does sound as if the Ampmeter is not the way to go.
I'll try to find a good source for Fluke and will check out the FHB
issue coming out on testers. Pretty timely.
I certainly agree about not cheaping out on a tester!
I generally try to buy the best tool I can possibly afford but in this case it's a no brainer. Electricity can sometimes fool even an electrician. I have no problem spending whatever it takes to buy the best tester.
Thanks,
Tom