measuring wire resistance

[dmz2711 10+ year member]

How do you figure out the resistance of different size wires? i know there is a way with a dmm to figure out the resistance, anyone know how?

also, can you use that resistance to determine voltage loss?//content.invisioncic.com/y282845/emoticons/crazy.gif.c13912c32de98515d3142759a824dae7.gif

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[JimJ 5,000+ posts]

Use the resistance setting...should be marked with a little omega symbol.

For voltage loss, just measure it directly //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[dmz2711 10+ year member]

Use the resistance setting...should be marked with a little omega symbol.
For voltage loss, just measure it directly //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

yeah, but do i measure it at the begining and then the end or somethin like that??? what is the procedure to measure resistance of a wire?(as you can tell i do not have much experience with this) //content.invisioncic.com/y282845/emoticons/crazy.gif.c13912c32de98515d3142759a824dae7.gif

 

[JimJ 5,000+ posts]

Both ends - one probe goes on one end of the wire, the other goes on the other end.

 

[project f-150 10+ year member]

Just make sure your meter is reading 0 first. Sometimes they will show a slight resistance without anything on them. Or just touch the two probes together first and seewhat resistance comes up. THen subtrack that from whatever the wire meters at.

 

[dmz2711 10+ year member]

Both ends - one probe goes on one end of the wire, the other goes on the other end.

Just make sure your meter is reading 0 first. Sometimes they will show a slight resistance without anything on them. Or just touch the two probes together first and seewhat resistance comes up. THen subtrack that from whatever the wire meters at.

awsome!!! thanks guys i appreciate it!//content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[dmz2711 10+ year member]

one last thing....

to measure resistance the wire does not need to have current running thru it correct??? it automatically has resistance as a plain power wire?

so to measure resistance of a 10' long 1/0gauge power wire, just insert one probe in one end and the other probe in the other end???

what if the wire is installed in my car and i cannot reach with the 2 probe's? can i put the positive probe on the wire, and the negative probe on the car chasis? how can it be done(the procedure)?

 

[helotaxi 5,000+ posts]

With a normal DMM you won't be able to measure the resistance of a 10' piece of 1/0. It's too small. If you want the resistance of a piece of wire, look it up in a wire guage resistance chart.

 

[dmz2711 10+ year member]

With a normal DMM you won't be able to measure the resistance of a 10' piece of 1/0. It's too small. If you want the resistance of a piece of wire, look it up in a wire guage resistance chart.

ok, cool. do you or anyone else, have any links or know where i can maybe find some type of publication of a wire gauge resistance chart? i've searched for it online, but no luck.... //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

 

[Flipx99 5,000+ posts]

What I did to measure voltage drop is to measure voltage at the battery then measure again at the amp. Then subtract battery - amp.

I consider good to be

 

[Flipx99 5,000+ posts]

ok, cool. do you or anyone else, have any links or know where i can maybe find some type of publication of a wire gauge resistance chart? i've searched for it online, but no luck.... //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

I think that would only be 'nominal' or'standard' your application may vary, I believe anyway

 

[wesl56 10+ year member]

ok, cool. do you or anyone else, have any links or know where i can maybe find some type of publication of a wire gauge resistance chart? i've searched for it online, but no luck.... //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

there is one stickied at the top of this forum!!

well.. it doesnt have resisitance, but it has load ratings which sould help u out

 

[helotaxi 5,000+ posts]

I think that would only be 'nominal' or'standard' your application may vary, I believe anyway

AWG is actually defined by resistance, not physical size with 10ga as the benchmark at 1 ohm per 1000'. The gauge above and below that is denoted as increase or decrease of signal in dB from the 10ga standard. For example, 13ga would be 2 ohms for 1000' and 7 ga would be .5 ohm per 1000'.

Here's a link to a resistance chart. http://www.bnoack.com/index.html?http&&&www.bnoack.com/data/wire-resistance.html

 

[dmz2711 10+ year member]

thanks for all the replies, hopefully i can figure all this out!!!

 

[KaeZoo 10+ year member]

You can directly measure voltage drop without doing any math. Just set the meter for DC voltage, put the black probe at one end of the wire and the red probe at the other end, and it will display the exact voltage drop through the wire. Voltage drop will vary with the amount of current running through the wire. No current flow, no voltage drop.