Cable left on reel?

Status
Not open for further replies.
E

EEC

Senior Member
Location
Maryland
What are some ways to tell how much cable are left on 1000 foot reels of MC? Or any other type of cable other than the d times 3.14 method.
 
another method that i've heard of, but haven't personally used is to weigh the wire.

If you have a scale that is big enough (but it might be more expensive and more trouble than the meter) weigh the full roll get a weight/foot. weigh the used roll and get a good guesstimate of the feet left.

never tried it though, usually just count the wraps and do some quick math.
 
You need access to both ends of the cable to perform any measurement tests.

You could do it by dimensions if you know the diameter of the spool. Or, by weight if you know the per foot weight of the cable and the tare weight of the spool.
 
We had a discussion about this awhile back....the consensus was that the only accurate and cost efficient way to measure cables was with a meter like this one:
34466.JPG


From GreenLee: http://www.mygreenlee.com/products/det.cfm?id=3378&upc=34466

I'm sure other companys make these things, I am familiar ONLY with GreenLee model/s....and they are dead-on. The above model will measure from a #16 to a 2000kcm cable.

The cost of the tool was esaily returned based on the number of times we used and the amount of wire we DIDN'T have to order - I'm talking hundreds of pulls of various sizes and lengths all on one project.
 
I'm glad to see that I'm not the only one will a zillion leftover pieces at the shop that I'm not using because I'm not sure exacly how much is left on the spool.
 
mdshunk said:
I'm glad to see that I'm not the only one will a zillion leftover pieces at the shop that I'm not using because I'm not sure exacly how much is left on the spool.
Click to expand...

Here's a "frugal" idea...take that "scrap" and buy a meter!

:D

What's #1 copper at? $3/lb?
 
mdshunk said:
Yeah, yeah... I guess the handwriting's on the wall.
Click to expand...

....and you might be able to see that wall if you didn't have all that scrap piled and hung all over the place ;)
 
mdshunk said:
True. I guess that's why they spool wire so that you can get to the beginning tail. ;)
Click to expand...

Marc,
I have seen many spools without both ends, particularly ones that have been re-wound or cut by a distributor.:grin:
 
One way to do it works like this. You need to know what the inside diameter of the spool is, along with the outside diameter of the partially empty spool. Count the number of laps of cable visible around the spool core. This is much easier if you have a full set of laps wound, but not impossible if you do not. If you have a partial outside lap, you can use the circumference of the inside lap and know you have a buffer to work with.

Let's say you have a core diameter of X inches. You count Y turns of cable which could be wound on each layer. You measure the outside circumference of the spool at Z inches. The thickness of the cable is W inches.
pi = 3.14159265358979, or 3.14, or 22/7, whatever you like.

(A). [Z + (2 * pi * X)] / 2 = mean circumference of spool

The reason I have you measure outside circumference and inside diameter is that those things are pretty easy to measure without unwinding the spool.

If you can guess the number of layers on the spool (n), all you need to do is to multiply the result of (A) times the number of layers on the spool (n) times the number of turns per lap (Y), and voila, you'll have an impressively close estimate as to the length of cable on the spool.

l = ([Z + (2 * pi * X)] / 2) * n * Y

One should consider the number of adult beverages recently consumed before publishing such an equation. Remember to multiply the mean circumference times the number of turns per lap.

If you can't guess the number of layers visually, what you do is this.

1. Measure the inside lap diameter (D0)
2. Measure the outside lap diameter (D1)
3. Measure the cable thickness (W)
4. take the result of step 2, subtract the result of step 1, and divide by the result of step 3.

n = (D1-D0) / W. This will give you n, the number of layers of cable.

Edited 2226 02 Nov 2006 - [(D1 - D0) / W] * Y * [(Z + (2 * pi * X)] / 2] = length of cable on spool
Make sure you use the same dimension (like inches, for example) for D1, D0, W, X, Y and Z
Result will be in the same dimensional units.

There. Close enough; bedtime for Bonzo now.
 
Last edited:
mdshunk said:
dsteves... I just elected you to swing by my shop and put length tags on all my leftovers.
Click to expand...
If the leftovers in question are #12 THHN or smaller, wound on spools of 3" or smaller diameter, you couldn't provide enough barley malt adult beverage for the author to estimate the length. That, of course, is a null hypothesis which must be disproved. So, get the beer ready and we'll find out.

Dan
 
Status
Not open for further replies.
Top