I have 2 Snap-On amp clamps to use with my Snap-On multimeter and am not sure that they are accurate. I bought them both used. I get different readings with both. Should I check them with a headlight bulb (said 55w on the bulb box ) and a 12 volt battery? Where should I take the voltage reading? At the Battery or bulb? Bulb lit or unlit? I will use the formula W=A x V. Once I figure out what the amp reading should be, should I then work backwards to get the correct amp reading in the multimeter with the amp clamp working on the live circuit with the adjusting knob?
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Checking amp clamps
- Thread starter johninct
- Start date
What amperage range are the amp-clamps?
Roughly what amperage do you intend to use them on?
If the amp-clamp is like 0-200 amp and you're only trying to measure something like 2 or 5 amps it's not going to be very accurate.
Also, make sure the faces of the clamps, where they close together are clean. If there is dirt built up there they won't be accurate.
Roughly what amperage do you intend to use them on?
If the amp-clamp is like 0-200 amp and you're only trying to measure something like 2 or 5 amps it's not going to be very accurate.
Also, make sure the faces of the clamps, where they close together are clean. If there is dirt built up there they won't be accurate.
RunninOnEmpty
Well-known member
If you're comparing to the power of the bulb, you would want to read the voltage at the bulb itself, but I don't think any light bulb is going to have a power rating accurate enough to use as a calibration standard.
theoldwizard1
Well-known member
Amp clamps are probably, at best, +/- 10% accuracy.
MadTinkerer
Well-known member
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- Jan 26, 2013
- Messages
- 213
Why not set up a circuit ( like your headlight bulb) and measure the amperage inline with the multimeter. Then compare that reading to what you get with the amp clamps.
Sal Bandini
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- Joined
- Aug 30, 2012
- Messages
- 989
Amp clamps are probably, at best, +/- 10% accuracy.
You better tell Fluke that.
http://en-us.fluke.com/products/clamp-meters/fluke-325-clamp-meter.html#techspecs
RunninOnEmpty
Well-known member
Why not set up a circuit ( like your headlight bulb) and measure the amperage inline with the multimeter. Then compare that reading to what you get with the amp clamps.
Yeah, using a normal (non-clamp) multimeter is probably a good idea to check calibration. They are much more predictable, accurate and precise.
Cope
Well-known member
Amp clamps are probably, at best, +/- 10% accuracy.
Fluke rates their i410 ±3.5 % +.5 amp AC or DC.