Need multimeter: Do inexpensive ones allow testing through insulated wire?

I've noticed here and there that the people servicing my A/C and Heating system as well as the power company guys all seem to show up
with this wizbang multi-meter that has an attachment that can just collar an insulated wire and read it.
I honestly don't remember if they were testing nominal voltage, or current flow, or if one or the other is impossible.
Are such things available inexpensively? There are many times when working with house (and car!) wiring that I really would bennefit from reading the characteristics of a line without breaking into it.
Thanks!
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On Sat, 21 Mar 2009 16:39:35 -0700 (PDT), "Thomas G. Marshall"

Clamp-on AC ammeters (for household power) are available for under $50US. Clamp-on DC ammeters (for the car) are typically much more expensive. Active technology (chips) are required for the clamp-on DC ammeter, but only a passive current transformer required for the clamp-on AC ammeter.
John
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On Mar 21, 8:10 pm, snipped-for-privacy@picaxe.us wrote:
...[snip]...

Ah Thanks....the term is "clamp-on". I was told that such things were not available (by my local Ace Hardware store guy), hence the post here.
Is nominal voltage measurable in such a way?
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On Sun, 22 Mar 2009 11:20:31 -0700 (PDT), "Thomas G. Marshall"

Oddly enough, many hardware stores carry them ... including Ace! (Hands up, anybody who's surprised.)
<http://www.acehardwareoutlet.com /(lb4l5iqktufvkj55vzyn2r34)/ProductDetails.aspx?SKU214368>
Many also include banana jacks that are used with standard test leads for measuring voltage; frequently just AC voltage, although some will do DC as well as basic resistance measurements.
The ones in hardware stores are usually Greenlee or Gardner Bender branded and feature large jaw openings and high ranges, appropriate for checking mains cables. They are also found with smaller openings and lower ranges for appropriately smaller jobs.
Better-than-hardware-store varieties can be found at places like <http://www.tequipment.net/TMTClampOnMeters.html
There are also add-on probes that terminate in banana plugs, intended to be used with regular multimeters.
--
Rich Webb Norfolk, VA

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On Mar 21, 8:10 pm, snipped-for-privacy@picaxe.us wrote:

Ignore prior question regarding voltage....asked and answered else- thread. THANKS!
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These 'clamp meters' are available in all price ranges. they only measure current using the clamp, the less expensive ones only measure A.C. current.
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Ah....gotcha.
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ac or dc voltage with contact points
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On Mar 21, 9:40 pm, snipped-for-privacy@verizon.net wrote:
...[snip]...

Sure; I was assuming that they were also "standard" multimeters.
Is there a brand people suggest for the low-end range? Here're an example of what I've done before (not in order).
1. General electrical installation within a house. 2. Inside a car, often rewiring something or other. 3. Repairing PC's, often trying to determine the degree a power supply is croaked. 4. Other DC wiring. 5. Testing impedance on A/C motors. (etc.)
So pretty much the home/hobbyist quality will work. I don't absurd impedance resolution, nor anything particularly special. I just want something competent.
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For work with mains wiring in a house an AC non-contact voltage detection probe is essential: http://au.fluke.com/auen/products/Fluke+1AC+II+VoltAlert.htm?catalog_name=FlukeAustralia&Category=ELT (FlukeProducts) You can get them on Ebay.

Any general purpose Multimeter will do the job you want. Fluke is best, but fairly expensive. Cheaper but brand name ones like Extech or Meterman/Amprobe are also good. Cheap no-name Ebay ones also work, but you get what you pay for quality-wise. You should not have to spend more than $50-$100.
Dave.
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http://au.fluke.com/auen/products/Fluke+1AC+II+VoltAlert.htm?catalog_name=FlukeAustralia&Category=ELT (FlukeProducts) I have something similar, a detector bought from Lidl, that can detect wood, steel and AC voltage, just by sliding it near the suspect area. It's very nice (www.lidl.de , www.lidl.gr ) Lidl is a supermarket, that brings along goodies like that, beyond the usual grocery.

--
Tzortzakakis Dimitrios
major in electrical engineering
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Yes, these "Stud Finders" all have AC voltage detection now too. But not as useful or precise (the range is very large) as the proper tool for the job.
Dave.
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I still can't figure out how the wood detection works, the other two are quite obvious. It works anyway. I haven't seen in any special shop (from where I buy wholesale materials) any such tool of good quality, like a fluke. Only the largest one carries a professional line of multimeters, I don't remember the brand, but an european version of Fluke. I even measure the leakage resistance of a heating element with the megohm scale of a multimeter, and not with a Meger as it's *supposed* to be, FWIW, and usually an earth leakage trips the main GFCI, anyway.
--
Tzortzakakis Dimitrios
major in electrical engineering
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Stud finders do not detect the wood, they detect the difference in the density or "hollowness" of the wall just like you can by tapping on the wall and listening to the sound difference as you pass over a stud. Electricians found studs that way for many years before the detectors were available.
Don Young
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Stud finders just use the change in capacitance (due to different dielectric constants) to detect the wood. Pretty basic stuff and not much to it at all. I layer out the board for and built one way back as a school project.
Dave.
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I commend you for asking the question on this group. And I do not want to lecture you...BUT if I knew anyone was to carry out any domestic electrical installation work and didn't know what a clamp-on (aka tong) ammeter was, i would be asking some serious questions as to their suitability for undertaking such work. May I suggest (at the very least) that you read a basic primer on electrical installation work before any more 'installations' to protect yourself and others associated with the installation. You do not mention where you are live but I presume from your ISP that it's stateside...and i am not familiar with the regulations over there. I know in Australia where I live now only licensed electricians can work on installations. Even home owners cannot work on their own domestic electrical installation. In the UK where i come from it is a bit easier and the law allows anyone 'appropriately ' qualified to work on an installation...but what is the definition of appropriate?...it's a little grey. The law may have changed since I left in 1994 anyway. Please do not consider this a 'dressing down' as it were..it's certainly not intended as such...just a plea for you to continue in your education via some appropriate training along the lines of, at the very least, a comprehensive, authoratitive training manual of some kind...there are lots to choos from. Please remember electricity can kill! Leaky taps cannot! Regards Daniel
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On Mar 22, 10:22 pm, snipped-for-privacy@gmail.com wrote:

...[snip]...
I know what an ammeter is...I've used the ammeter/voltmeter/ohmmeter within multimeters off and on for years. I didn't know that the term was "clamp on".
You've made an assumptive leap in logic here...there was nothing in my statement that suggested that I did not do proper research before any electrical installations. Nor is there anything that suggests that I'm not doing such research now.
Check your assumptions please. If what you wanted to ask was "are you comfortable doing such installations?" then ask. Don't go launching off with language sounding like an admonishment and then claim it isn't meant to be a dressing down. Particularly when you ran to ill- supported conclusions.
Posts like that are what damage usenet and make it less likely that others will ask questions. There's always someone's pedantic statement to wade through.
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In article

It sounds to me that you are likely to be in over your head. What are you trying to do? What do you mean b "read"? Do you want to read the imprint on the wire? :-) Other posters' guessed gthat you were describing a current measurement. Even if you got what you wanted, I would be concerned about your safety.
Bill
--
Private Profit; Public Poop! Avoid collateral windfall!

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I am not in over my head.
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Thomas G. Marshall wrote:

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber–308
It's a $9.99 clamp on ampmeter/dvm
You CANNOT read (all) "the characteristics of a line" without breaking into it. You CAN measure the current in the line without breaking into it, and the meter in question works only on AC current that way. For other measurements that this meter can perform, you need to use the probes to contact uninsulated ends of the line. And this meter does not measure everything you might want to know. But if you want a cheap AC clamp meter, it is probably worth the cost.
Ed
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