What’s the correct way to ground boat trailer lights?

Proper grounding is essential to keep your trailer lights working reliably, especially since boat trailers are regularly submerged in water. Poor or corroded grounds are one of the most common causes of lighting failures.

Main Trailer Plug

• Ensure the white ground wire on the main trailer plug is securely connected to the trailer’s tongue.
• Scrape away any paint, rust, or galvanizing so the connection makes good bare-metal contact.

Tail Lights

• Each tail light has a white ground wire that must make solid contact with the metal tail light bracket. If mounted on painted or galvanized steel, clean the surface before tightening.

Clearance Lights

• Single-wire clearance lights must be anchored directly into a metal fender bracket for grounding.
• If installed on a plastic fender, run a separate ground wire from the light’s stud to the steel trailer frame or fender bracket.

Boat Trailer–Specific Considerations

Corrosion Protection: Saltwater accelerates corrosion at ground points. Use dielectric grease, heat-shrink connectors, or marine-grade sealants to protect connections.
Frame Bonding: Ensure your trailer frame provides a continuous ground path. On galvanized or aluminum trailers, always clean to bare metal at contact points.
Extra Grounds for Long Trailers: Add secondary grounding points along the frame to prevent dim or flickering lights, especially for side markers.
LED Lighting: LED lights are less forgiving of poor grounds than incandescent bulbs. Make sure connections are tight and corrosion-free.
Inspection Frequency: Inspect grounds before each boating season and more frequently in saltwater environments, as corrosion develops faster.