Question for any sparkies out there. What is the difference between the regular type and the clamp on type multimeters?
I know the clamp types can read amperage using the clamp but seems that the more traditional multimeters have more dial settings.
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Replies
The clamp ones are mainly for working on the electrical systems of buildings. The more general purpose meters are better for electronics work, where you need things like millivolts DC.
-- J.S.
It depends on what you want to do.
There are basically three types of multimeters/testers for electrical wiring:
1) The traditional VOM -- volt/ohm/ammeter. Can be analog or digital, purely mechanical or electronic.
2) The clamp-on ammeter. Generally a mechanical analog meter in the lower end units.
3) The "wiggy" -- a device that vibrates when connected to AC voltage.
In general, you cannot read AC current (very easily) with #1, but it's handy for general troubleshooting in appliances, cars, and occasional home electrical circuits.
#2 is probably the best choice if you only have one device for home electrical (not appliance/electronic) work. It will have an AC voltmeter in addition to the AC clamp-on ammeter. Generally comes with a plug/socket device to allow you to measure the current draw of 120V appliances as well. Generally useless for auto work or electronic work, though (except possibly for some high-end digital models that have DC ranges).
#3 is best for working with possibly "hot" circuits in that it give you an unambiguous indication as to whether a circuit is hot. A problem with #1 in particular is "ghost" or "phantom" readings due to capacitive pickup between adjacent wires.
(I have -- and use -- all three.)
I was looking at a Sperry Instuments clamp on type $50. Its digital. Would that be best for working with circuits in a house and some electronics?
Does it have any DC ranges? The standard clamp-on only has AC ranges and only usually 250 and 600V ranges. For general home/auto use you also want DC volts, at least, and down to maybe a 10V low range. Plus you want ohms, something not always present in clamp-on units.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
This is the one I was looking at. I think it has what you recommend no?http://www.awsperry.com/sperry/catalog?item=digisnap-500
The 540 would be OK, I suppose, though the ohms ranges are less than ideal for general work. The 500 is AC-only.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
"The 500 is AC-only."Just for the current.They both had DC voltage measurements..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
The 500 is what I have for power work. I made a plug adapter for checking current on tools. I plan to change it to a ten-turn design so I can get in effect a 4 Amp scale.
-- J.S.
Gee, my old Radio Shack unit came with an adapter with both 1:1 and 10:1 loops.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
It would work, but not great, specially for more than just checking 120/240.You lowest amp scale is 40 amps. So that it you check an appliance you are way down in the scale, but it would probably be accurate enough for that.But for volts the lowest scale is 400 volts for either AC or DC. Not too good for things like 12 DC auto circuits or 24 AC HVAC. You could use it to determine if you have a voltage or not, but not as good if you need to find voltage drop problems for example.If you can find at similar cost, but some lower range scales I would get it.But as I said you can test a lot with that, just not "ideal".But scrolling through the Sperry Specs all of those that I see with lower voltage ranges have 400 amp or larger current ranges. So I would say that it is the best of the Sperry line except for the 540 which also adds DC current..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
What's hard about reading AC with a VOM?
MikeInsert initially amusing but ultimately annoying catch phrase here.
Nothing hard about it. What's hard is NOT reading AC when there's none there/
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
You have to cut the lead and run it through the meter. And meters are typically limited to 10 amps or they go up in smoke or blow a fuse..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
OK, not clear whether you were talking AC current or voltage. First off, many multimeters don't have AC current ranges. And those that do, as was said, require you to somehow wire the meter in series with the circuit to be measured. Finally, a clamp-on can easily measure hundreds of amps, whereas the practical max for a standard multimeter is around ten amps -- not even sufficient for a single lighting circuit.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
If you don't know what the difference is 'tween a multi-meter and an amp-clamp, what you need to start out with is a good book on using a meter for electrical testing. Really.
To get useful information from a tester or meter about an electrical system, you need to understand how the system works normally. Then you use the tester or meter to see if the voltagte, current, resistance/impedance, or capacitance of the system is what it should be. If things aren't what they should be, the cause of the problem (or the next test or measurement step) is generally obvious.
To add to what DanH and others have said--
--an amp-clamp measures current (electron flow) in a circuit. Many multimeters will do this, but youhave to put the meter in the circuit so the current runs through the meter. This is sometimes difficult (if you have to cut a wire) or hazardous (you've got the full current at circuit voltatge running through the test leads and meter--energized terminals and such are exposed, and if there's a power surge, it could blow up the meter).
--many amp-clamps have the ability to measure voltage and other parameters. They're basically a clamp-on ammeter and a digital multimeter on one package.
--amp-clamps that measure DC current in addition to AC current are very expensive.
--the most common situations in which I use an amp-clamp are to troubleshoot large motors, and three-phase systems.
--the other instance where I use an amp-clamp, mostly in commercial where wires are in conduit, is as a circuit tracer/finder. I have a lampholder (socket) with clip leads, and a flasher button in it with a 75 watt lamp. I put this on the far end of a circuit and can use the amp-clamp to trace the wires along the way--I open a j-box, and with my amp-clamp look for the wire (hot or neutral) that has a reading that alternates by about 0.6 amps. Hwlps identify the hot and the neutral, great in circuits with shared neutrals (common in commercial, also found in residential). I'm using this a lot less since I got my Ideal Sure-Test circuit tracer--it's amazing.
Good luck and work safe--
Cliff
<what you need to start out with is a good book on using a meter for electrical testing>Any suggestions? I have a multimeter and have no idea how to use it.
Need it to troubleshoot/fix dead audi,dead cub cadet,dead Honda 250 - all with suspected electrical problems and sitting for two long - plus basic household electrical.Funny, my brother was a trainer for Bosh and ran a auto electronics biz for many years, and I don't have a clue. The peckerhead won't help me, either.Todd
See if Radio Shack still has one of those "How to use your multimeter" books. Not great, but not too bad.Also, for general use, one of the cheapie RS multimeters (they start at $4.95 or so) is perfectly adequate (though I'd probably hold out for something in the 20-30 dollar range).But if you do much work with electrical wiring then getting the clamp-on is a good idea. No reason why you can't get both.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Thanks. I actually have a clamp on, seems to function although can't find brand...it's a freebie.Preciate the suggestion, heading to RS tomorrow anyway for something else.Todd
Also, go to amazon.com and search "books" for "multimeter". There are several likely suspects listed.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Or else just go to Google and type in "how to use a multimeter". There are several pages' worth of online tutorials and videos.
Cliff?
Could you post a link (or give me the model number) of the Ideal tracer you have? I have one (GB I think) that was given to me and I'm kicking around springing for something better. Don't use it all that often but when I need one, they're invaluable.PaulB
Paul,
Here's the link:
http://www.idealindustries.com/tm/SureTest.nsf
I recommend the middle model. The better receiver is worth it. The clamp-on transmitter is excellent in certain instances but the kit w/transmitter and better receiver is about a k-buck.
I've used many different types of circuit tracers over the years, and the Ideal Sure Test is the best so far. It really works--with four levels of sensitivity, when the receiver indicates that a specific breaker is the source of a circuit, you can count on it. Great for tracing wires, and even works well for landscape lighting and irrigation valve wire and power cable buried up to a foot or two in soil.
I have the kit with the inductive clamp. It's great to be able to clamp it on a wire, anywhere in the circuit, and trace the wire in either direction. When I'm doing commercial old work, I just clip the clamp on a conduit and can trace the conduit above the drop ceiling from suite to suite.
Recently I was doing some work on a 60s house that was rewired in the early 80s. The tracer didn't show one breaker as the clear source--it showed two breakers at about half signal strength. I thought, Crap! The Sure Test has failed me!
It turned out that the device I was interested in (a switch feeding a light fixture) was fed by two different breakers--both off the same pole or leg. Well, the Sure Test had it right, after all.
Keeping in mind the original post, it's important to know what to expect in a normal (properly wired and operating) system, and it's just as important to keep an open mind when your testing shows something unexpected. There are an a lot of ways a residential electrical system can be screwed up. One of my favorites is the time I found a 14/2 cable between receptacles in a bedroom that had been used to extend both switched and non-switched power from one receptacle to a second one...
The circuit was set up with a half-switched receptacle properly wired with a 14-3 wg cable running from switch to receptacle. Some goofball wanted the next receptacle in line to be switched, but the others down the line to be non-switched. What he did was use the grounding conductor of the romex to carry switched power! And he hadn't disconnected the grounding conductor on the downstream side--so when the switched power was on, the receptacles down circuit had an energized grounding conductor. Just a good thing that most table/floor lamps and appliances are non-grounding.
You just never know what you're gonna run into...
Cliff
That sounds a little better that what I have. But much more expensive.I have a $29 Idea CB finder.The receiver is near worthless. SOMETIMES I can get it within 6 breakers.I worked up a panel legends on a house with 320 amp service and two 150 amp panels and one of those feeded a sub-panel.I could not even ID which of the 3 panels the circuit was on.But I found that it made a clicking sound that I could pick up on a AM radio. So I kept one in my pocket tune off station and then flipped breakers until I found the one.I found a couple of wiring problems in my own house similar to what you describe.I have an open LR, dinning room with the kitchen off on an L, also open.I was painting the LR/DR and when I removed a switch plate in the LR part the DR and kitchen light flickered.There was a switch for the kitchen lights that was wired with 14-3 to feed the main light and also have a hot that feed other lights including the DR light and some pathway lights between the LR,DR and kitchen, with 3/4 way switches. One of which in the living room.The 14-3 had a short from neutral and ground to hot. So they cut off the neutral and ground on each end. Then in the kitchen light they tied the neutral and ground together on the outgoing leg.That part of the ground ended up in the LR box. In that same box was switches for other lights and they where on a different circuit.I don't have it it was code at the time (79) or not, but the two sets of grounds where connected together. Just pushed into the box and happened to touch. That is until I took of the switch cover and they moved a little.Nothing in the panel was marked so that was a good time to trace the circuits. Got most of them and ended up 6 that I could not ID them. One was for the furnace, but I flipped them off and on one by one and the furnace never went off.So I turned them all off an then on one by one and found that the furnace was on two.I have two furnaces mounted side by side. They ran 14-3 to it. Unlike the first problem I suspect that the furance installed do this, but really not sure.At the furnace they tied the two hot to one switch and feed the two furnaces. Then move one of the breakers so that they where on the same leg..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Clamp on is for amperage.
Mike