Help adding conditions and formula to workbook.

[paul700grizzly]

I am working on a feeder workbook that we will put our wire lengths, runs, sets and wire type into. The help i am needing is something that is beyond my capabilities, here is what i need it to do and any help will be much appreciated. The formula will need to be typical all the way down the sheet in column L, row where the circuit number is. If you open the drop down menu in E7 there are different wire sizes. I need to asign weight per foot to each of these which we will call 909090 for formula sake. The catcher for me was if you open drop down menu C4 there is CU & AL, there will be different weights for all the wire sizes under CU than AL. The C4 choice that is made at the start of the workbook and applies to the entire sheet. Here is the formula that needs to be applied to L7, L12........L7=B7*C7*D7*(the weight that is applied to the E7 wire choice. I have attached the worksheet if you would like to see what i am working with. Thanks in advance for any and all help!!!