clamp multimeter

[chiragpatnaik]

This is going to sound like a ridiculous question, but here goes anyway.

I was planning to buy a digital multimeter for small projects and kit assembly (ice clock and monochron to start with). I had zeroed down on the mas830L.

I was wondering if I could get a clamp multimeter instead. Would serve the dual purpose of testing voltagesand current consumption around the house.

If so, what is it that I need to look out for? Will any clamp multimeter do?

[jpbot]

I have a Fluke clampmeter and it's feature set has nothing on my multimeters. I would not recommend a clamp meter unless you really know you need one.

There are some clamp meters that work in DC circuits but they are generally for AC circuits. You cannot simply clamp a clamp meter around the cord headed to your PC or whatever to measure current, it must be on one current carrying conductor at a time (or same phase). Clamping a power cord where the hot and neutral are running through the clamp causes the current reading to show as ZERO amps.

Besides the clamp meter knows nothing of watts and power factor. A cheap Kill-A-Watt is much better for household current readings.

As for a multimeter, are you just starting and don't know if you'll use the meter a lot or are you pretty sure you want to have a nice comfortable meter? In the Adafruit store there is a budget minded http://www.adafruit.com/products/71 offering which has a big display, though I have no experience with it I'd expect it to be one of the best values in what is really a throwaway price range.

For the money this Extech meter seems like the way to go: http://www.adafruit.com/products/308 Again, no personal experience but with the exception of true RMS AC ranges this meter has it all, including capacitance, frequency and even a temperature probe---so you can go around finding out your refrigerator isn't cold enough (that's what I did when I got a meter with a temp probe!) The Extech is auto ranging too!

The mas830L you mention shows a transistor tester which might be handy, but probably unnecessary.

Whichever you choose be sure to read the manual so you learn all the tricks of your new tool.

[mimran]

In order to use a clamp meter, only one conductor is normally passed through the probe; if more than one conductor is passed through then the measurement would be the vector sum of the currents flowing in the conductors and would depend on the phase relationship of the currents. In particular if the clamp is closed around a two-conductor cable carrying power to equipment the same current flows down one conductor and up the other, with a net current of zero. Clamp meters are often sold with a device that is plugged in between the power outlet and the device to be tested. The device is essentially a short extension cord with the two conductors separated, so that the clamp can be placed around only one conductor. it helps me to design refrigeration system project.

[chiragpatnaik]

I have a Fluke clampmeter and it's feature set has nothing on my multimeters. I would not recommend a clamp meter unless you really know you need one.

There are some clamp meters that work in DC circuits but they are generally for AC circuits. You cannot simply clamp a clamp meter around the cord headed to your PC or whatever to measure current, it must be on one current carrying conductor at a time (or same phase). Clamping a power cord where the hot and neutral are running through the clamp causes the current reading to show as ZERO amps.

Besides the clamp meter knows nothing of watts and power factor. A cheap Kill-A-Watt is much better for household current readings.

As for a multimeter, are you just starting and don't know if you'll use the meter a lot or are you pretty sure you want to have a nice comfortable meter? In the Adafruit store there is a budget minded http://www.adafruit.com/products/71 offering which has a big display, though I have no experience with it I'd expect it to be one of the best values in what is really a throwaway price range.

For the money this Extech meter seems like the way to go: http://www.adafruit.com/products/308 Again, no personal experience but with the exception of true RMS AC ranges this meter has it all, including capacitance, frequency and even a temperature probe---so you can go around finding out your refrigerator isn't cold enough (that's what I did when I got a meter with a temp probe!) The Extech is auto ranging too!

The mas830L you mention shows a transistor tester which might be handy, but probably unnecessary.

Whichever you choose be sure to read the manual so you learn all the tricks of your new tool.

The reason my question for the clamp was a series of electricity related issues around the house and each of these guys came with a clamp meter. The guy who come to fix our Air conditioner used the clamp around the power cord which had a live and neutral coming down the same line. He declared that the current drawn was 60 amps (eeps. Now I know why the socket would keep getting burned out) and that was because of a shot compressor. Called another guy, who did what you mentioned after opening up the AC and said thecapacitor was shot which was replaced and all was well.

Another guy for an inverter etc. Thought will get one and diagnose some of things myself.

Anyhow. Thank you, for the detailed reply. It does answer my question.

I am starting out. Plan to do a bit more in electronics. Not sure, If I want to buy top-of-the-line equipment right now.
But would appreciate an opinion on what are the core features one should be looking for.
I figured MAS 830L (recco'd here in one of the tutorials) would be fine (It's about $10 in India) If it is missing some features what are they (and why if you have the time). and the nearest model in terms of price range.

Thanks in advance.

Chirag

[adafruit_support_bill]

The Mastech 830 and similar meters have enough capabilities for most of the projects here. Higher-end meters have features like auto-ranging which makes them easier to use.

If you will be working with mains circuit wiring, you might consider something like the Extech330 which has a "Non-Contact Voltage Detector". I use this to verify that the power is really off before working on mains circuit wiring.

[john444]

Hi Chirag,

It is feasable to use a common multi-meter for service work
but it is not practical to us a clamp meter for electronic work.

Clamp type meters are generally not as accureate as general purpose multi-meters.
They do not need to be.

I would recommend you purchase a good quality multi-meter that you can rely on for years.
If you find that you have the need, you can always purchase a clamp accessory probe to use with your multi-meter.

Good luck, John

[john444]

Hi Jenas,

The website seems to say +/-1%.
They make a number of different meters/clamps.
Sorry I cannot answer your question about the 14".
The Swain meter I used was very sensetive to the orentation relative to the earth's magnetic field.
For DC current less than a few amps, you put the clamp over the conductor, fix the meter in position,
zero out the offset, energize the conductor and take the reading.
The meter has to be very still while taking a reading.

Good Luck, John