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I decided to get the clamp meter in the image. And it say AC Current:60A/600A/1000A

  1. What does " AC Current:60A/600A/1000A" mean ? It only has one option for Amps AC.

  2. I was doing some testing and I observed I can measure the AC current of my toaster oven using the clamp meter. Which was using 9 amps. However, when I tried to do a test on my table lamp. I got no reading. Is it because the amp usage is too low ? Does it have anything to do with question 1 ? OR is it because the table lamp is using two wires where as the toaster oven has three wires because of the ground. I am only measuring one wire of the whole in the clamp meter.

product on amazon

enter image description here

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  • See electronics.stackexchange.com/q/581648/152903
    – Solar Mike
    Commented Aug 14, 2021 at 23:21
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    Be clear: Are you somehow separating one wire feeding the table lamp and just putting the meter clamp around the one wire?
    – Hot Licks
    Commented Aug 14, 2021 at 23:50
  • @HotLicks yes, I split a 3 wire extension cord from which I clamp onto one conductor. And I feed the device into the extension cord
    – ender maz
    Commented Aug 15, 2021 at 0:05
  • I'm shopping around more. And It's not standard to support higher resolution low amp reading. But apparently they are out there
    – ender maz
    Commented Aug 15, 2021 at 0:07
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    Try using the "range" button for 60/600/1000 selection. Actually the dial has different positions for 60/600 and 1000, not "only one" as you say. Perhaps start with looking at your meter and it's manual a bit more closely...
    – Ecnerwal
    Commented Aug 15, 2021 at 0:24

4 Answers 4

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The major sellers of Mastech meters are Amazon, eBay, AliExpress, Konga, Joom, Indiamart and wish.com. That is a huge red flag for cheap counterfeit crud, right off the boat.

If that fact did not reflect the price you paid, that's because crud sellers have discovered people are more likely to buy it if it's up-priced comparable to quality units. Also Mastech is a real brand, they just don't sell test equipment. This "brand predation" is very typical of "those guys".

I bought a modest quality Klein unit last year for around $50, so I don't see any reason to pay that much for junk.

The lamp didn't produce a reading because its current draw is negligible - perhaps 0.1 amp assuming you are using modern bulbs.

If you cut up any line cords to wrap the meter around 1 wire, you need to replace those line cords, or shorten them and replace with a UL-listed retrofit plug.

The normal way of testing cord-and-plug connected equipment without slicing up the cord is to use a line splitter as Doxylover discussed. Some just spread the wires for you, for a 1x reading. Others wrap the wires 10 times around the hole, giving you a 10x reading -- helpful for things like that lamp.

enter image description here

10x makes sense. Most clamp ammeters range to at least 200A, and 20A is the max for anything that plugs into this type of socket.

Realistically I think you got much too large a clamp meter for residential-tier activities. If quality were equal, a larger "max limit" means poorer resolution on small measurements.

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  • My $80 klein clamp meter came with a line splitter.
    – JACK
    Commented Aug 15, 2021 at 1:22
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    You need a special leakage clampmeter if you want really high (mA) level resolution Commented Aug 15, 2021 at 4:07
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What does "AC Current:60A/600A/1000A" mean?

That means the meter can measure three ranges and report them on its four-digit display:

  1. 00.00A - 60.00A (0.01A resolution)
  2. 000.0A - 600.0A (0.1A resolution)
  3. 0000A - 1000A (1A resolution)

It only has one option for Amps AC.

Incorrect. It clearly has two different positions on the "range" dial for measuring current: "60/600A" and "1000A". If set to the former, it will "auto-range" and figure out which is appropriate.

Your table lamp likely draws only a fraction of an amp (a 60W filament bulb at 120V is 0.5A; LED/CFL bulbs are going to be more like 0.1A). The 1000A scale cannot display fractional amps. Try the 60/600A setting.

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  • It might auto-range. Or it might need the range button to be used.
    – Ecnerwal
    Commented Aug 15, 2021 at 0:28
  • I tried range button, but nothing. I got a 0.045 Amps using someone else's clamp meter that has a range of 2/20/200/400 Amp. 0.045 A seems too low. But that's what it said
    – ender maz
    Commented Aug 15, 2021 at 1:21
  • OK yeah, it's one of those LED/CFL bulbs.
    – ender maz
    Commented Aug 15, 2021 at 1:31
  • @nobody, well it clearly doesn't start at 0
    – ender maz
    Commented Aug 15, 2021 at 1:35
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    @endermaz 0.045A at 120V is 5.4W. That corresponds to about a “40W equivalent” LED/CFL. Totally normal.
    – nobody
    Commented Apr 19, 2023 at 15:11
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For low currents put the wire through 2 or 3 times and then divide the reading by the number of turns.

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  • Normally that would work, But I need to use it on my fridge. I want to measure amp usage of some of the components in there. And they do use small amps. I was hoping not to cut the wiring
    – ender maz
    Commented Aug 14, 2021 at 23:28
  • I was hoping this clamp meter that is in the higher end would be able to measure amps...
    – ender maz
    Commented Aug 14, 2021 at 23:30
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    Measuring amps is what clamp meters do. They can't measure anything else, they don't have access to voltage to arrive at V, VA, W, ohms, PF or anything like that. Commented Aug 15, 2021 at 0:16
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your all wrong .It's not for use on a chord with both a neutral and a live the current flows in both directions cancel your reading out. end of story You need a single wire.

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  • Yes, the current flows in both directions. That's what AC means.
    – Chenmunka
    Commented Apr 19, 2023 at 14:16
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    Yes, the clamp has to surround a single wire of the pair, or field from the two wires will cancel out. However, as everyone has said, a splitter, or a split extension cord, or equivalent solves this, and the original poster has said they're using that approach. So, no, everyone is right and you didn't read carefully enough; this is a range issue, assuming the meter isn't malfunctioning. You might want to delete this answer.
    – keshlam
    Commented Apr 19, 2023 at 14:47

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