How to Install a Generator in a Cargo Trailer

by John Cagney Nash

Installation of a generator on a cargo trailer can be useful for many reasons. For instance, some cargo trailers are used to transport perishable goods and need to be refrigerated, while others are used as mobile workshops and must have functioning lights and outlets. Cargo trailers are seldom factory-fitted with a generator-ready bay, meaning a fuel line, exhaust system and wiring harness are provided. However, aftermarket generators are almost universally pre-wired and fitted into a frame with an integral fuel source and muffler system, so installation is relatively straightforward.

Step 1

Determine the most convenient location for the generator. Because cargo trailers usually have access doors that take up the entire rear wall and no underfloor storage bays, the most common location for a generator is on the towing tongue. Lift the generator into its desired location and use a permanent marker pen to mark the positions where pre-drilled holes in the generator frame match up with the tongue rails. There should be at least three sites. Temporarily remove the generator.

Step 2

Use an electric drill to drill holes through the marks, and lift the generator back into position. Fasten it using nut/bolt/washer combinations tightened with a socket set and a wrench. Consult the generator's installation guide to confirm that the generator's starter motor is grounded through its frame.

Step 3

Fit a battery box with an integral converter charger near the generator, unless the generator is a pull-start model, and install a 12-volt lawnmower battery. Secure the battery in place using the built-in strap or metal gripper rail. Connect the negative pole of the battery to the chassis of the trailer using 6-gauge automotive white wire, and follow the generator manufacturer's instructions for starter motor and charger connections to the positive pole of the battery and the converter charger.

Step 4

Connect the outlet panel of the generator to a fuse-board or circuit breaker board inside the cargo trailer. It is from this board that connections to the trailer's 120-volt circuits should be made. Use type-UF residential wire rated for the maximum amperage the generator can create, and conventionally color-coded with black or black/red pinstripe wire for hot, white wire for neutral and green wire for ground. The generator's outlet panel should have three clearly marked terminals for these wires. Use wire strippers to remove a half inch of insulation from each wire, insert the bared ends one at a time in the appropriate terminals, and then use a screwdriver to tighten down the terminal screws.

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