Question. I've added additional LED lights to the Bull Bar in the pic. I purchased a wiring harness kit from Amazon with its own controllable switch. I'm looking for power source that is ignition controlled (meaning fog lights don't work when the key is off). When I look at the fuse box under the hood (5.0 engine) and also the fuse box by the passenger feet----the empty fuse spots are not pre-wired with terminals. Where should I tap in for power? Thanks.

 

I used an "add-a-circuit" off fuse #77 in the fuse box under the hood (also 5.0).
This thread should have all the info you need:
https://www.f150forum.com/f38/lookin...se-box-460502/

NOTE:
After using this power source for a while; I've noticed it cuts off after the key is turned to the off position.
I thought it would cut off when the driver door was opened after turning off the vehicle.
It doesn't bother me for my applications; just thought it was worth mentioning.

 

you should really be using a relay with the main power going to the battery and the add-a-fuse being used as the trigger.

 

The link I provided above also has a diagram I drew explaining the relay installation.
YES, use a relay!