Non Contact Voltage Tester?

I am in the process of installing a shitload of T8's in my parents' kitche. BUT, there was a severe electrical storm today, and I'm paranoid about lightning. So I just walked around Lowes in the electrical section looking at all the goofy plugs. I looked at the wire strippers and other assorted tools and came accross this Gardner Bender Circuit Alert Non-Contact Voltage Detector Model GVD-504A Apparently one waves it around an electrica cable to detect the presence of AC power. Sounds pretty nifty. Do these actually work? Wouldnt there have to be a "flow" of power, and therefore a load on the line for it todetect anything? Or can one simply have nothing on the line and just an open LIVE circuit?

Reply to
Edward
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I have a similar one and it seems to work. It detects the magnetic field of a hot wire (I assume), and it doesn't need to have the juice flowing to work. Just a hot wire is all it needs.

Reply to
Mark

Hmmm, Magnetic compass will do the same by delfelcting the pointer.

Reply to
Tony Hwang

What?

Reply to
Edward

Mine works pretty well. I think I paid $13 for it (?). Just make sure you test it on a known live circuit first to ensure the battery hasn't died. Cheers, cc

Reply to
James "Cubby" Culbertson

Exactly. trusting my life to something I get from wal-mart... Has me a bit uneasy. When I opened up the fixtures I was going to replace, a little voice told me to get one of thse magic wands. The breaker was turned off... but still. I don't know why.

Reply to
nntp.aioe.org

I guess its time to check my Outlook express settings too.

Reply to
Edward

They are the cat's meow. I have seen some that have jaws like a pair of pliers, too. It saves time if you just want to check a cord, etc. I love mine.

Steve

Reply to
SteveB

I use a different brand. Quite useful. You can determine if a wire is a hot when the color might not indicate - like knob & tube.

They work by detecting the electric field.

The gimmics that identify the circuit breaker for an outlet put a current signal on the circuit at the outlet and detect the signal in the magnetic field at the breaker.

As James said, test it before before you trust it.

-- bud--

Reply to
bud--

I'm not too wild about these for voltage checks, although they are the cat's pyjamas for finding where a cable run is behind the drywall (saved myself from nailing through in the wrong spot more than once now). If you are at risk from getting zapped by leads in a conn box somewhere, better by far IMHO to check with a multimeter. You can get one at Canadian Tire or Home Depot or wherever at a pretty reasonable price, and they're pretty good quality and precision, unless you're an electronics enthusiast looking for four decimal places.

While personally I prefer analogue meters, they do have some potential problems such as low input impedance (meaning they can "load" a circuit down), and it's too easy to get erroneous readings or damage the meter if you forget to select the correct range. Most digitals are either auto-ranging or will give you a warning if your input exceeds the range setting.

One thing I would stress is whether you go for analogue or digital, check that it's rated at least Category II. This relates to what kind of transients it can handle. Category I is the lowest; and is considered suitable for electronics and telecommunications equipment. Category II is for branch circuits - lighting, appliances, 120/240 volt distribution inside a building. Category III is for distribution circuits, feeder panels, etc.; basically anything up to the utility transformer. Category IV is the highest level. Obviously the higher category rating you get, the more expensive the meter will be, all else being equal.

Yours aye, W. Underhill

Reply to
William Underhill

Tony Hwang wrote in news:8Cyri.19055$fJ5.5448 @pd7urf1no:

60 times a second? Bit rough on the eyes, no? :-)
Reply to
Al Bundy

Hi,

Yes these things do work and work well. It saved me a few times. The one I have is made by Fluke and would recommend it.

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What they do is detect the Electrical field around a wire and beep when there is one. Note that they do not work by detecting a magnetic field that Mark (another poster) mentioned. When no current flows there is no magnetic field. I.E. if you have a hot wire dangling around in the air, it will have not magnetic field because there is no current, but it will have a Electical Potential field, and it is this that the Voltage tester picks up.

The nice thing is, unlike a multimeter which you need to make pysical contact to a piece of metal, you can check if a lead is hot or not without having to strip it or to get at a metal contact. This is nice in that you are always insulated from electrical power. Checking with a multimeter is also a good test. I do both, first with the VoltAlert, then with the multimeter.

best, Mike.

Reply to
hobbes

The Gardner I have churps when you 1st press the clip...to tell you if the battery is OK. It can't identify a blown 220V cartridge fuse.

It can't be detecting magnetism...there isn't necessarily a flow of current for it to ID a hot wire.

Reply to
pheeh.zero
[snip]

The first time I saw one of these testers, it was advertised for checking miniature holiday lights (commonly 50 in series). I wish they had told what it was actually sensing.

Reply to
Mark Lloyd

You lost me. Did you think it was checking for the spirit of Christmas?

Reply to
mm

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