To determine where to make the first mark on the conduit for a 20" stub-up when the bender deduct is 8", we need to follow these steps:
1. Understand the Problem: We need a 20-inch stub-up, which means the vertical height of the conduit after bending should be 20 inches. The bender deduct is 8 inches, which is the amount we need to subtract to position the mark properly for the bend.
2. Setup the Equation: The position of the first mark can be found by subtracting the bender deduct from the desired stub-up length. In other words:
[tex]\[
\text{First mark position} = \text{Stub-up length} - \text{Bender deduct}
\][/tex]
3. Substitute the Values:
[tex]\[
\text{First mark position} = 20" - 8"
\][/tex]
4. Perform the Subtraction:
[tex]\[
\text{First mark position} = 12"
\][/tex]
Therefore, you should make your first mark 12 inches from the end of the conduit. The correct choice is:
c. 12" from the end of the conduit
