A fuse block does it properly. Tapping random wires does not.
Tools required
Tool one, tool two.
Before you start
The warning that saves someone a repair bill.
Step 01 — Choose the fuse block
What to do, and what it should look like when it is right.
Step 02 — Mount and earth it
What to do, and what it should look like when it is right.
Step 03 — Wire the trigger
What to do, and what it should look like when it is right.
Step 04 — Label everything
What to do, and what it should look like when it is right.
If it goes wrong
The two or three most likely mistakes and how to undo them.