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Author Topic:   Why are trailers grounded using the frame?
Chuck Tribolet posted 11-14-2005 02:36 PM ET (US)   Profile for Chuck Tribolet   Send Email to Chuck Tribolet  
Other than simple cheapness, why are trailer lights grounded
using the frame? It's been a reliability problem for me.


derf posted 11-14-2005 02:40 PM ET (US)     Profile for derf  Send Email to derf     
Because cars and trucks are. You can easily run a ground wire and connect it to your vehicle frame.

derf posted 11-14-2005 02:40 PM ET (US)     Profile for derf  Send Email to derf     
Oh, BTW, trailer lights are a reliability issue for just about everyone.
Chuck Tribolet posted 11-14-2005 03:39 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
You don't need to tell me that. I'm getting ready to replace
all the wiring in my trailer. I plan to run a separate
gound wire from each light to a common point (up inside the
winch stand). Connections will be soldered and sealed with
Ancor hot melt lined heat shrink.

The ground connection has been one of the ongoing points of failure.


derf posted 11-14-2005 06:38 PM ET (US)     Profile for derf  Send Email to derf     
That Ancor adhesive lined heat shrink is good stuff.
I think most grounding problems with trailers relate to dirty hitches and balls.
Jerry Townsend posted 11-14-2005 08:56 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
Chuck - I don't see any problems with using the trailer frame as a grounding conductor.

The biggest problem that many have is using the hitch/ball as the ground connector - which has proven to be very unreliable and flat guaranteed to cause problems.

The best way, in my mind, is to use a solid ground connection to the vehicle frame, a connector providing a conductor pair for the ground, and a solid ground connection to the trailer frame. Protect the ground connections against corrosion on the vehicle and the trailer.

Then, simply running a ground connection from each fixture to the frame will suffice - it is not necessary to run all grounds to a common point. ---- Jerry/Idaho

where2 posted 11-14-2005 11:09 PM ET (US)     Profile for where2  Send Email to where2     
For all the boating that Chuck does, I am surprised he has not upgraded to runnnig wired grounds prior to this. The Trailer for my 15' Sport has been wired with additional ground wires ever since my father converted it to LED trailer lights as a Christmas present several years ago (it's nice when dad lives 4 houses down the street). I no longer wonder whether the lights will work. They simply work. Don't forget to add ground wires to the side marker lights. Regular trailer wire is CHEAP wire. Why it has not been upgraded to tinned wire is an unanswered question of cost versus added benefit. Do yourself a favor Chuck, locate a spool of 4 conductor tinned marine wire, then rewire your trailer.
Chuck Tribolet posted 11-14-2005 11:36 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
The ground problem is NOT the ball. The ground conductor
comes off the four pin connector, and goes to a screw under
the bow. All the lights have their ground conductor screwed
to the frame. That screw has been problematic.

What's really crazy is that the side marker lights on the
fender have their ground go all the way back to the tail
lights. It would actually be shorter to run the wire forward
to the connector ground screw.

I've been procrastinating the all wired ground for some time,
waiting for some decent LED tail lights in the right form
factor, which have finally appeared. They aren't the
perfect size, but they'll bolt up. SS bolts built in.
Tinned marine grade wire. White LEDs for the license plate. West Marine brand!!

Now that they have appeared, it's time to get serious.

Four conductor would be the wrong answer. There are seven
lights. Only one gets left, only one gets right. I'm goint
to run Ancor 16 ga. primary wire. All seven lights get ground
(white) and tail (brown). Left and right tail lights get
left and right (green and yellow, or is it yellow and green
(don't worry, I'll check before I start pulling wire. About
250' of wire total for a 17' boat. Oh yes, a Jet Connex plug, soldered on.


Backlash posted 11-15-2005 08:48 AM ET (US)     Profile for Backlash  Send Email to Backlash     

I agree with Jerry that it's not necessary to run all grounds to a common point, just ground at each light.

I also think using marine grade tinned wire on a trailer is overkill if you use the Anchor hot-melt heat shrink connectors which effectively seal the exposed bare wire ends. Equally important is to use split loom to protect the wiring where any chaffing may occur. I also used all SS fasteners when connecting lights, grounds, etc.

I think you will love the LED lights.


jimh posted 11-15-2005 09:17 AM ET (US)     Profile for jimh  Send Email to jimh     
Use a star washer on the ground screws. This will end your problem.
Backlash posted 11-15-2005 09:34 AM ET (US)     Profile for Backlash  Send Email to Backlash     

About 10 years ago I "bit the bullet" and bought an Anchor ratcheting crimper - around $40 back then as I recall. The ratcheting mechanism will not release until a perfect crimp is formed. This crimper not only crimps the wire, but also the plastic collar on the connector. This tool produces professional factory looking crimps and is highly recommended.


Chuck Tribolet posted 11-15-2005 10:52 AM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
There is a star washer. It's still been troublesome.

And I do have the Ancor racheting crimper. Nice. About
$100 now. There are (at least) two. One for single crimp
(ie, the hot melt heat shrink, one for double crimp where
the crimp has a metal collar that crimped around the
insulation for strain relief. Mmmm, and there's probably
a third for no insulation.

I'm going to throw some overkill at this. The original
wiring has wire cancer, so needs to be replaced. It will be
a bunch of work (I figure a day) so I'm going to do it very


Bulldog posted 11-15-2005 01:30 PM ET (US)     Profile for Bulldog  Send Email to Bulldog     
Chuck as you originally stated, 12 volt systems use the frame, because they can and it is cheaper! You will be better off using copper as an electrical conductor in a sealed wiring system instead of the steel frame of a trailer that is starting to rust the first day you use it!....Jack
andygere posted 11-16-2005 12:07 AM ET (US)     Profile for andygere  Send Email to andygere     
Chuck, if you want to get the boat off the trailer while you work on it, you are welcome to use my slip in Santa Cruz. My boat is in the driveway, and will be for a while.
Chuck Tribolet posted 11-16-2005 04:05 AM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
Thanks for the offer, Andy, but it can all be done with the boat on the trailer. Now, when the time comes to replace
the bunk boards, I may take you up on that offer.


andygere posted 11-16-2005 02:09 PM ET (US)     Profile for andygere  Send Email to andygere     
The offer stands Chuck. If you just want to use it to do some diving in the area, you're welcome to do that as well. Since my boat is in the water most of the time, I've gotten used to doing all my dreaded trailer maintenance with the boat completely out of the way. It's a small luxury...
Chuck Tribolet posted 11-16-2005 02:32 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
The consensus in the local dive community is that the diving
is lots better on the south end of the bay. There are a few
hunters with secret spots off Santa Cruz. But thanks.


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