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.
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.
"Thomas G. Marshall" wrote:
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.
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
4. Other DC wiring.
5. Testing impedance on A/C motors.
So pretty much the home/hobbyist quality will work. I don't absurd
impedance resolution, nor anything particularly special. I just want
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.
Oddly enough, many hardware stores carry them ... including Ace! (Hands
up, anybody who's surprised.)
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
There are also add-on probes that terminate in banana plugs, intended to
be used with regular multimeters.
For work with mains wiring in a house an AC non-contact voltage detection
probe is essential:
(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
You should not have to spend more than $50-$100.
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
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-
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.
(FlukeProducts)> I have something similar, a detector bought from Lidl, that can detect
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.
To please a couple of the more pedantic characters in this thread, in
the interest of full disclosure I thought I'd explain how it is I am
I am installing a light fixture. When I took the old light fixture
off I noticed in the ceiling that there was a black wire that came in
and was tied to another black wire that continued the run. From my DC
days I know the black wire to be ground, so I spliced into it and
attached the light's green wire.
I think the fixture is faulty because when I connected it's white wire
to the white wire in the ceiling I felt a little funny. But my
circuit breaker is also faulty because it threw right away.
Downstairs I couldn't get the breaker to stay in one position, it was
that worn, so I put a self-tapping screw direction through the top of
the switch to hold in the on position.
Light works! But buzzes & flickers horribly. Lots of noise in the
breaker box too. I'm blaming the switch upstairs....it's the only
thing left. I know that it isn't a 3 way switch because it only goes
two positions, so I'm not quite sure what is going on here. I can't
even guess what the red wire up there is for.
There's always some wire left behind in all my installations....you
know how it is.
Green is safety ground & black is hot, not ground. The green is
never to be used to connect anything other than the frame of the
fixtures, outlets or switches.
White is neutral, black is hot, green is safety ground. Your
conections are in violation of the electrical code, and could kill
The two black wires connected in the box allowed the AC line to
continue to the switch, and return on another wire, which is likely
white, but should be marked red or any color other than green or white.
Its no wonder your breaker is tripping.