sadly enough, im kinda lost here. In this example.....
Quote:
The surface area is 1 sq.ft., the current density is 4.5 A per sq.ft.
720 / (4.5 / 0.5) = 80 minutes for 0.5 mils thick.
The current you would apply is:
4.5 ASF x 1 sq.ft. = 4.5 Amps.
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if you worked those numbers out backwards it doesnt work....
720= ASF x minutes x mils
720= 4.5 x 80 x 0.5 <---that isnt correct
What am I missing? I couple more examples of the 720 rule would be appreciated, I would like to try it out this weekend.