Question: I'd like to install a light and lighter socket in the camper shell of my pickup. I really haven't done anything like this before and figured it would be best to get some advice. What's the best way to get power back there?

Answer: It's a good thing you're taking the safe route doing this, as there are a few ways the project could go wrong. First, let's consider what you may want to operate from the lighter socket. Most plug-in gadgets are likely to use less than 10 amps of current - the exceptions being bed/raft inflators, and perhaps a 250 watt (no larger) power inverter at a little over 20 amps. If we combine this potential electrical load with a light or two, it would be best to use 12 gauge or larger wire and a 25-30 amp fuse. The robust wire will allow maximum performance of your plug-in accessories.

I'd begin with a peek below the truck to see on which side the manufacturer chose to run the rear-lighting wiring harness. It's usually tucked in neatly within the frame rail, and you'll want to run the new wire along this same path. Next, check for an accessory stud or receptacle under the hood, where battery + can be safely and conveniently accessed. If there isn't such a place you'll need to tap in at the battery positive terminal, or in the case of a side terminal battery, at the back of the alternator (disconnect the battery before working here).

The first and most important thing to connect will be an inline fuse holder at the source of battery + (install the fuse only when completely finished with the installation). These can be bought at an auto parts store or Radio Shack. I'd choose the ATO (blade) fuse type, so it matches the fuses likely used elsewhere in the truck. If the wire leading to the camper shell gets into trouble (chafes against, burns, or becomes crushed between) vehicle metal, or your lighter socket load is excessive, the fuse will pop, offering essential protection. The second wire (ground) can be attached directly to the truck frame beneath the bed, rather than running it all the way to the engine compartment (remove paint or underseal where it bolts to the frame).

When routing the positive wire, allow sufficient slack in anticipation of movement between the engine and chassis, and be careful of hot or sharp-edged areas along its route. I'd recommend running the wire within some 3/8-inch convoluted plastic tubing - Home Depot sells this far cheaper than anywhere else I've seen. While there, also pick up a bag of 6-inch zip ties and a sturdy rubber grommet suitable for two 12 gauge wires. The zip ties will be used to safely secure your wires, perhaps every 18 inches or so along their route, and the grommet will protect the wires as they pass through a likely sharp-edged hole drilled in the pickup bed.

Connecting the fuse holder and wire terminals will require a wire crimper and assorted insulated terminals, often available as a kit. I'd wrap electrical tape around each wire/terminal junction to help seal out corrosion and to offer some protection should the intersection come apart. Finally, imagine your truck being driven in a grueling off road race - fully considering the effects of vibration, flying rocks and movement of your wire installation. Extra time and care will make this a onetime/lifetime installation.