I used the dimmer hot wire to a relay, and the relay to ground. Then wired directly from the + battery terminal, through a fuse, then through the firewall, to the in and out of the relay, to a rocker switch, back through the firewall, then to each fog, and grounded each fog. Did you catch all that?
The relay allows you to tap the parking light switch without pulling much more current through that circuit. Also, with this approach, the fogs have their own fuse. So if my fogs blow the a fuse, my parking light circuit remains untouched.
Try wiring everything up outside of the car first, then can see how the circuit works.
This is what I did in a nutshell
Except instead of the fusebox, i used the dimmer switch hotwire