# Re: [TCML] how much wire

Wire Length in feet regardless of cone or helical coil = (turns x (top radius + bottom radius) x pi) / 12
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400 turn inverse cone with a bottom radius of 4.5" and top radius of 2"

(400 x (4.5+2) x 3.14)/12 = 680.7 ft.

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So yes, 840 ft should more than do the job and 22G would be the correct choice of wire size.
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Bart

On 11/24/2012 11:36 AM, david baehr wrote:
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Hello,            Figuring  wire length  for a conical coil.  Take circumference of  base,... circumference of top , add & divide by two , then use the basic  TPI ??                For a cone 9" bottom , 4" top ,  12" high , and approx  400 turns  ,  840 feet should more than do the job ?                   Thanks for any help ,  (mathematically challenged ) daveB   ,,,,   any good heavy build  #22 wire for sale ? 		 	   		  _______________________________________________
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