How to properly use a clamp multimeter? - Page 1
Forum section: electronics / beginners

author: od1
author_rank: Newbie
timestamp: September 27, 2021, 02:45:27 pm
content: Hello everyone!I chose the UNIT-T UT204+, partly after reading a post here. I'm very happy with its features, as I was with an other UNI-T meter I own.But I can't figure out how to use the clamp! Which is a shame as it is the main purpose I had for this new meter!As I understand it should work by turning the dial to 60A, press the yellow button to set it on AC and place the clamp around the cable I want to measure. Here's a video of my attempt:https://www.dropbox.com/s/z7papknf50jqark/IMG_0965.MOV?dl=0I guess (and I hope!) I'm doing a stupid mistake, please let me know which one!Cheers

author: RoGeorge
author_rank: Super Contributor
timestamp: September 27, 2021, 02:54:45 pm
content: Clamp around only a single wire, not around a cable containing 2-3 wires, because the wires inside will cancel out each other's field, and you'll only measure zero.

author: od1
author_rank: Newbie
timestamp: September 27, 2021, 03:01:12 pm
content: Quote from: RoGeorge on September 27, 2021, 02:54:45 pmHo! That makes perfect sense, thank you @RoGeorge!So, let's say I want to measure my extension cord, or my washing machine, all I have to do is wiring a special extension cord with the phase / neutral / ground separated, and clamp the phase independently from the others. Right?

author: wraper
author_rank: Unknown
timestamp: September 27, 2021, 03:11:39 pm
content: Quote from: od1 on September 27, 2021, 03:01:12 pmYes.

author: Alti
author_rank: Frequent Contributor
timestamp: September 27, 2021, 05:36:17 pm
content: For measuring current drawn by a washing machine you do not need clamp meter, just use any kill-a-watt. These also show power, peak power, current, peak current, cos(phi), voltage etc.The clamp meter is used for maintenance and diagnostics, mostly in electrical cabinet. That is the whole idea of clamping it over a live wire and that is why it is insulated. Stripping an extension cord not recommended.

author: ledtester
author_rank: Super Contributor
timestamp: September 27, 2021, 11:24:34 pm
content: You can also use an "AC line splitter" like this one:Extech 480172 AC Line Splitterhttps://www.amazon.com/Extech-480172-AC-Line-Splitter/dp/B0000YHN9W

author: David Hess
author_rank: Super Contributor
timestamp: September 28, 2021, 12:08:07 am
content: Old clamp meters came with an attachment with an outlet plug on one side and an outlet socket on the other:https://www.amprobe.com/product/els2a/The extra clamp position has 10 turns for 10 times sensitivity.

author: wizard69
author_rank: Super Contributor
timestamp: September 28, 2021, 12:31:45 am
content: Quote from: od1 on September 27, 2021, 03:01:12 pmYes! You can make a special cord or you might be able to find an adapter that does this.In the industrial / machine controls world I like to make sure there is enough wire at the contractors to do this without major disruption in the panel box.As for things like a washing machine, if you want to measure motor current you will need to find the right leads to the motor. While a washing machine might not have a huge current demand outside of the motor it is usually a good idea to get the actual device current.

author: RoGeorge
author_rank: Super Contributor
timestamp: September 28, 2021, 09:22:18 am
content: Quote from: od1 on September 27, 2021, 03:01:12 pmYes.Instead of wiring your own extension, it might be easier to just strip the second isolation from the power cord of a commercial extension socket. Strip it only over a short length until you see the 3 isolated wires inside, so you can clamp each one individually.

author: od1
author_rank: Newbie
timestamp: September 28, 2021, 11:11:13 am
content: Quote from: Alti on September 27, 2021, 05:36:17 pmI'll look into that, seems indeed more appropriate (and secure).Quote from: ledtester on September 27, 2021, 11:24:34 pmHo I've seen those before! But EU models seem quite rare and pricy...Quote from: wizard69 on September 28, 2021, 12:31:45 amI'm specifically interested in the heating element consumption. This would help me to figure out if my WM uses timer or thermostat to control the heating element.