Single wire running lights

[Richrad]

I’m getting ready to mount running lights on my wooden trailer. Just got some really nice teardrop shaped ones from Vintage Trailer supply. However, they are single wire with no obvious grounding lug. What is the best way to ground them? They have mounting holes through the stainless steel bases.....just wire to the screws?

[redbicycle]

The trailer chassis is often used as a ground. They are likely designed that the mounting screw would be grounded to the metal chassis. It is easy to test by running 12v+ to the one wire and - to the metal trim of the light. If you have illumination you can either screw the lights into the metal chassis, or use a crip on end on a wire and run that under one of your mounting screws.

[Andrew Herrick]

The trailer chassis is often used as a ground. They are likely designed that the mounting screw would be grounded to the metal chassis. It is easy to test by running 12v+ to the one wire and - to the metal trim of the light. If you have illumination you can either screw the lights into the metal chassis, or use a crip on end on a wire and run that under one of your mounting screws.

Redbicycle is certainly correct. If using a steel chassis, use a star or toothed washer or manually grind off the paint around the mounting hole so that you ensure metal-to-metal contact between the mounting stud/screws and the frame.

[Benno]

Pretty sure he said he has a wooden trailer.

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[Andrew Herrick]

Pretty sure he said he has a wooden trailer.

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This is why TNTTT needs a palm-to-forehead emoji. How did I miss that?! Thanks for pointing it out.

Well, grounding to the screws is certainly an option, but I would make a little modification. Drill mounting holes through the trailer frame and use machine screws with nuts to attach the lights. Then you can use a heat-shrink ring terminal on the nut-side of the machine screw - use a little threadlocker on the nut - and keep everything clean.

[Richrad]

You had me at "heat shrink ring terminal". Never heard of such a thing! Gonna do just as you recommend. Thanks, Rich

[Shadow Catcher]

I will second use of the ring terminal but use Dielectric grease and a washer between the wood and light.

[Andrew Herrick]

I will second use of the ring terminal but use Dielectric grease and a washer between the wood and light.

Excellent advice. I'm a little spoiled in the Southwest USA; bare steel hardly rusts outside! But yes, diaeletric grease will reduce corrosion and save you the hassle of freaking about over a "broken taillight" on vacation