fog wiring

16 gauge wire is fine for terminals 85 and 86, they only activate the relay, so since it takes very little current to activate the relay, about 200ma, you can use a smaller gauge wire.  Your feed and output wire size is dependent on the current that the output device will use and the length of the wire from the relay to the output device. 

So you would have to have an idea of how many amps the fog lights will be pulling and how long of a wire you need to where the lights are mounted.  14 gauge might be marginal for fog lights, I would use 12 gauge for both the power feed to terminal 30 and the output feed to the fog lights.  Same goes for the ground for the lights. If you use 12 guage for the 12V feed, then you need to use 12 gauge on the ground coming from each light.

Your local auto parts store should carry primary wire in several gauges and colors in small 12-25-foot rolls. I would try there first.  Wire is like everything else, you get what you pay for. Here is a site I found that has an assortment of inexpensive wire to choose from:

http://doityourself.com/store/wire.htm