Trying to find the AWG of a wire without seeing it - Page 1
Forum section: electronics / beginners

author: littlebill
author_rank: Regular Contributor
timestamp: August 18, 2019, 12:50:28 am
content: I am trying to determine the "average" awg of a wire run without being able to see the entire wire.is a 4 wire resistance test the only way to determine this, or is it not possible? is it possible to determine length as well?please be kind.. I am new at this

author: ledtester
author_rank: Super Contributor
timestamp: August 18, 2019, 01:13:53 am
content: I often determine AWG by putting it into a wire stripper and seeing which of the notches work:The correct notch is the smallest one that doesn't nick the wire when you close the jaws.Can you tell us more about your situation? If you are considering a 4-wire measurement it seems you must have access to the two ends and the ends are close to each other.Also, are we talking solid or stranded? And why do you say "average"? Isn't the wire all the same throughout the run?

author: littlebill
author_rank: Regular Contributor
timestamp: August 18, 2019, 01:46:47 am
content: The wire as stated is unable to be seen through its entire run, i have access to the end and the beginning, it is expected to have splices, and i don't like to assume things such as consistent wire gauge through the run. the wire will be stranded

author: ledtester
author_rank: Super Contributor
timestamp: August 18, 2019, 01:53:40 am
content: And what are you going to do with the average?If you want to know what the resistance of the run is, then a 4-wire measurement will tell you that.If you want to know how much current you can safely pass through the run, then you want to know what the minimum gauge is along the run -- i.e. the weakest link.

author: littlebill
author_rank: Regular Contributor
timestamp: August 18, 2019, 02:35:55 am
content: Quote from: ledtester on August 18, 2019, 01:53:40 amagreed but if i can't see it, how would i determine what the minimum gauge is in the run? and my issue is voltage drop, not currentbased on my reading you have to know the length of the wire to do the 4 wire test to determine awg, but i am open to suggestion i may have another way to determine what i need to know, but i would like to still know if its possible with the above conditions

author: Stray Electron
author_rank: Super Contributor
timestamp: August 18, 2019, 02:49:12 am
content: If all you're interested in is voltage drop then use a 4 wire ohm meter and find the resistance. Then measure the current draw of the load or get it from the specs and calculate the voltage drop. E=IR. Even if you knew the wire size you couldn't find the resistance unless you knew EXACTLY what the wire was made of. Much of the wire out there today is cheaply made and is FULL of impurities.I don't know what your application is but if it were me I probably won't use the wire unless I knew what it was made of and what size it was and how well insulated it was and the condition of all of it.

author: ledtester
author_rank: Super Contributor
timestamp: August 18, 2019, 03:09:13 am
content: If it's only voltage drop you're concerned about just measure the resistance of the run. Try using your multimeter. If it gives you an answer of "0", you might not have any issues depending on the amount of current you'll be using. If you get a non-zero answer then you can calculate what the voltage drop will be for your application's current usage. What multimeter do you have?You can double check what your multimeter tells you by estimating what the resistance should be based on the gauge and length using a chart like this:https://www.calmont.com/wp-content/uploads/calmont-eng-wire-gauge.pdfI don't know of any practical method of measuring the minimum gauge appearing in a run.

author: vk6zgo
author_rank: Super Contributor
timestamp: August 18, 2019, 04:03:29 am
content: Use it as a draw wire to pull a known sized wire through!