weighing 12 awg wire spools to determine length of wire left on them

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Has anyone SUCCESSFULLY tried weighing used 500 foot spools of #12 wire to approximately get the length left?
There are some good handheld digital scales that people weigh luggage with. And I thought it might work for this application too.
Hate guessing that a half spool will make it to my panel on long homeruns.
 
This could work if you knew the tare weight of the spool and had a very accurate scale. You would find the gross weight of a new 500' spool, deduct the tare weight and find the net weight of the 500' of wire. Then you would have a number (divided by 500) representing a fraction of a pound, ounces, or even better, grams per foot and multiply that by the measured weight to see what's left on the spool. I'm not so sure that a luggage scale will be accurate enough for what you're trying to do.
 
First you need to know what the plastic reel weighs and then you need to know what a foot of wire weighs. Put it on the scale subtract the reel weight and you have your answer.
 
PetrosA said:
If you have a decent multimeter, this might be easier:

http://www.cirris.com/testing/resistance/wire.html
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That is kind of what I have done with reasonable success. I use a different calculator that I found on line- may have to come back later with it, but it takes into consideration temperature as well which should give even more accuracy. Is also best to have the meter and the wire measured to have been sitting in the same environment long enough that they are both same temperature to the core for the best accuracy.

Wire length meters that I have used in the past require same temp environment for both the meter and wire for most accurate results.
 
cowboyjwc said:
First you need to know what the plastic reel weighs and then you need to know what a foot of wire weighs. Put it on the scale subtract the reel weight and you have your answer.
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If you know the weight per foot and how much wire is on the reel when new, you can figure the weight of the reel without actually weighing it.

If the wire weighs 1/10 of a lb. per foot and I have a 500 foot spool that weighs 55 lbs, I would guess that the spool would weigh 5 lbs.
 
K8MHZ said:
If you know the weight per foot and how much wire is on the reel when new, you can figure the weight of the reel without actually weighing it.

If the wire weighs 1/10 of a lb. per foot and I have a 500 foot spool that weighs 55 lbs, I would guess that the spool would weigh 5 lbs.
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That is true. I guess when I answered, I was thinking that he had partial spools. It's pretty simple, that's how they figure out your rolled coins. Know what a penny weighs and then put it on a scale and if it comes up short then it's not a full roll. That's how they count screws and what not in parts houses. My wife used to work for a transducer company that made the parts for those kinds of equipment.
 
kwired said:
That is kind of what I have done with reasonable success. I use a different calculator that I found on line- may have to come back later with it, but it takes into consideration temperature as well which should give even more accuracy. Is also best to have the meter and the wire measured to have been sitting in the same environment long enough that they are both same temperature to the core for the best accuracy.

Wire length meters that I have used in the past require same temp environment for both the meter and wire for most accurate results.
Click to expand...

It sounds like a calculator designed to be used with an ohmmeter will take the wire temperature as one input. In that case the temperature of the ohmmeter would not matter.
But a wire length meter with its output in feet would want to include automatic temperature compensation. In that case the meter would have to be at the same temperature as the wire it is measuring.

Tapatalk!
 
GoldDigger said:
It sounds like a calculator designed to be used with an ohmmeter will take the wire temperature as one input. In that case the temperature of the ohmmeter would not matter.
But a wire length meter with its output in feet would want to include automatic temperature compensation. In that case the meter would have to be at the same temperature as the wire it is measuring.

Tapatalk!
Click to expand...
You are probably right. I always seem to run into situation of wire is warm and meter is cold or vice versa. Take two readings even only a minute or so apart and they are not the same, keep both wire and meter in same stabilized temp environment and consistency is much better. The meter I use needs to be zero calibrated before measuring. If you bring a cold meter inside, calibrate it and wait a minute you no longer have zero when touching the leads together, it needs to be in stable temp to be most accurate.

kbsparky said:
Why can't the wire manufacturers imprint the footage on the wire? They do this with CAT-5 wire. Why not on romex or THHN?
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I thought there were some out there that do that, maybe some of the newer Sim-pull products?
 
I would HIGHLY recommend one of these:

http://www.amazon.com/UEi-Test-Inst...qid=1393511047&sr=8-3&keywords=uei+wire+meter

The time you waste weighing and guessing at the footage on spools, would be better spent putting it towards buying one of these. It will do all the different cable sizes. Were you planning on weighing every different wire size? Or just #12? That's time consuming, then some spools like #10 come on plastic and wood. You'd have to weigh both.

It has also helped cut down on our shop inventory. Our shop guy goes through the leftover spools and hangs labels with the wire lengths left on each one.

I agree with the footage marker comment too. Why can they do it on low voltage cables but not THHN?
 
I have one of these and I will see if it can measure a roll of romex and roll of 12 stranded

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