Recovery Rate of Wire Without A Scale

There are many threads here that mention recovery rates of insulated copper wire. Most of the time it has been mentioned to weigh a length of wire on a scale, strip it & weigh it again. Divide the lesser weight by the larger weight, move the decimal point two digits to the right and you have your recovery percent.
I’m going to show you a couple different ways to determine recovery rate without a scale. These might not be quite as accurate as a scale but will get you very close. I have done both the measure & calculate and weigh and calculate on identical lengths of larger diameter wire, both methods were within a couple % of each other. These methods will work on single stranded and solid wire and OK on multi strand wires like power & extension cords. My examples are using a digital caliper & a drill gauge.
First set of example & pictures shows a single stranded wire. Strip one end, twist wire and measure OD of copper. Measure OD of insulation. Formula is to divide smaller OD by larger OD. In this case .045 divided by .105= .4205. Move the decimal point two digits to the right. Recovery rate on this piece about 42%.
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Next example & pictures show a 3 strand computer power cord. Stripped and twisted ends measure .096, OD of outer insulation is .306. Divide .096 by .306, result is .313. Move decimal point two digits to the right. Recovery rate is about 31%.
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Last example & picture shows a 3 strand computer power cord. Stripped & twisted ends in closest fit hole is .093, OD of cord in closest fit hole is .312. Divide .093 by .312 the result is .298. Move decimal point two digits to the right and the recovery rate is about 30%. Examples 2 & 3 are the same wire measured two different ways, pretty close in outcome.[IMG][/IMG]


So how might this benefit someone? It may help you quickly determine the stripped vs. selling out right value of any quantity of wire of the same diameter. An example would be you have 100lbs of insulated wire and using one of the methods I described you determined a recovery rate of 55%. Your 100lbs of wire is worth XX.XX unstripped at the yard. You have 55lbs of copper based on your recovery rate. Your stripped copper is worth XX.XX at the yard. Will help determine if it’s worth it dollar wise to strip, the other variable now what’s your time worth.
Another way you could use this is to prove to your yard that what you have is a certain % recovery rate, might help you get better pricing, Just make sure you know the result before you try to prove it to them, your wire might not have the recovery rate you think it does and you get docked pricing.
For some readers this info I laid out won’t make a difference if you’re getting wire for free and your yard has limited grades of ICW then maybe no big deal. If you are buying wire this simple method may narrow down values before you make a purchase decision.
FYI Christmas lights, checked 3 different strands. All were 30-35% copper recovery rate.
Sorry for the funky picture sizes and long post, hope this makes sense (cents?) for you.

Originally Posted by DWJ

As in the case of the Christmas lights, in a comparison using an actual scale to measure pre-stripped vs. stripped Christmas light wire wouldn't you end up with closer to an 16-18% recovery rate and not the 30-35% you indicate via your metrics? Thanks again for opening this discussion.

I did actually weigh some examples Christmas wire and strip it. Wanted to verify some results using the strip & weigh vs. what I have shown. The Christmas wire I did strip was around the 30% area. I do agree though that density plays a huge factor in recovery rate and weighing is the most accurate option. Just wanted to toss another concept out there that would get reasonably close for those that may not have a scale.