How to Attach Ground Wire to Frame?

[wlooper89]

I want to attach a DC negative wire to my trailer frame and am trying to think of a good way to do that. I will probably crimp and solder a ring connector to a #10 wire but am not sure how to attach that to the steel frame, preventing rust and having good electrical contact.

Any suggestions? Thanks!

Bill

[Ageless]

You need a bare metal surface for proper conact. Then you coat it with dielectric grease/ Coat all eposed metal with the grease

[Miriam C.]

You can also get a grounding post from any dc supplier. I used ring connectors and nuts and bolts. Had to clean them up on this last trip. Clean up, is a great yearly chore.

[jeep_bluetj]

Clean to bare metal.

Ring terminal, self tapping screw.

Prime and paint over top of it all when it's assembled.

Same idea as the dielectric, but lasts longer.

[madjack]

Clean to bare metal.

Ring terminal, self tapping screw.

Prime and paint over top of it all when it's assembled.

Same idea as the dielectric, but lasts longer.

yep, that is how it is done on my boat trailer and so far, 13yrs and no light problems.............

[Steve_Cox]

You don't need no stinkin ground wire to the frame.

Dedicated ground wires always work better, most of the time 12V failures are due to a faulty ground.

[bobhenry]

You don't need no stinkin ground wire to the frame.

Dedicated ground wires always work better, most of the time 12V failures are due to a faulty ground.

I would like to second that thought !

Having worked for U haul and having hooked up several thousand trailers lighting problems were almost always related to poor grounds. Each and every 12 volt application on Chubby have a dedicated ground that runs back to a central grounding block and a dedicated ground wire is ran to the tow vehicle.

[Shadow Catcher]

There is not a good reason to use the frame for a ground! I think this is the message Steve is trying to get across with some force.
Run ground wires to each fixture and treat as you would any other connection. You and I have discussed being fans of soldering and using heat shrink tubing or tape. Particularly in a DC system yo do not want resistance.

[wlooper89]

You don't need no stinkin ground wire to the frame.

Dedicated ground wires always work better, most of the time 12V failures are due to a faulty ground.

Thank you for all the sometimes spirited responses. After reading the techniques described I will go with the Jeff and Madjack method of using primer and paint on the attach point.

Steve's response also has merit and was funny too! I did put in ground wire returns to my fuse block for the trailer circuits. It is just that the trailer running lamps were grounded to the frame by the builder with a single #18 gage wire and the attach point is rusting already. Where possible I will add separate and heavier ground wires to the lamps, including all the ones in the tail area. But six of the lamps would be difficult to access. These include the forward side markers and to a lesser extent the front and rear clearance lamps on the fenders. So for those I plan to use the original #18 gage wiring from a new junction box in the tail area that will be fed by heavier #12 wires.

The original #18 brown tail light wire will only power a 12V relay, also in the J-box, delivering power to all tail lamps from a #12 wire connected to the tow vehicle battery charge circuit.

The tow vehicle charge circuit is already connecting my trailer battery to ground, even while camping with the #18 running light ground. This new ground to the trailer frame is just to upgrade that connection with a heavier wire and correct the rust problem.

:thumbsup: You can also get a grounding post from any dc supplier. I used ring connectors and nuts and bolts. Had to clean them up on this last trip. Clean up, is a great yearly chore.

The grounding post mentioned by Miriam sounds nice. I will check to see if Harbor Freight has one of those.

Thanks everyone!

Bill

[cokebottle10]

You can get a SS bolt, say 1/4-20 x 1-1/2. Weld the head to the frame. This will leave you with a 1 1/2 inch stud that will not rust. (you have to paint the weld)

If you can not get any body to weld it. Then drill a hole in the frame and bolt a SS bolt to the frame with a nut and star lock washers. (not split washer) Then add another nut to the bolt for you ground wires. If you do this then use the dielectric grease. (auto parts store, use on spark pulg boots)

I plan to do this with both the 120 volt AC and the 12 volt DC on just one stud in just one place. I will not use the trailer frame as a wire. I will run a ground wire to each of the 12 volt lights and the brakes.

Thanks,
David.

[Ageless]

To clarify; 12V fixtures common to the trailer uses a separate ground wire. Tail and running lights use frame ground. If you also have 120 AC circuit; that too grounds to frame.

[Larwyn]

Bill, I cannot believe that you, the "King of Electrical Overkill", do not have a proper copper ground through a proper copper ground wire!!!!


Just joking around, don't shoot.

[wlooper89]

Larwyn,
You are right! I have engaged in electrical overkill in one or two areas. But it was only recently that I realized the trailer battery and converter DC were grounded to the trailer frame all along. Checking something else with the ohmmeter revealed the connection. After thinking about it for a while I remembered that the 7-way connector ground wire goes to both the trailer battery and the the running lights via the trailer frame, and that the battery has that connection to the frame even when the tow vehicle is not connected.

So naturally the present #18 wire and rusty screw have got to go, to be replaced with something substantial. Your mention of a proper copper ground sounds interesting. I will check to see if the local Harbor Freight store has those.

Thanks for the idea!

Bill

[wlooper89]

You can get a SS bolt, say 1/4-20 x 1-1/2. Weld the head to the frame. This will leave you with a 1 1/2 inch stud that will not rust. (you have to paint the weld)

If you can not get any body to weld it. Then drill a hole in the frame and bolt a SS bolt to the frame....

This idea sounds good. I do not have access to welding so drilling a hole for a stainless steel machine screw should be good. Dielectric grease will help create a solid electrcal connection and the SS parts will not rust. I like attaching both the AC and DC ground wires at this point too, as I want to have a good trailer frame connection for both. That will be easy in this case because my running light and forward AC junction boxes are close together.

Bill

[Larwyn]

You can get a SS bolt, say 1/4-20 x 1-1/2. Weld the head to the frame. This will leave you with a 1 1/2 inch stud that will not rust. (you have to paint the weld)

If you can not get any body to weld it. Then drill a hole in the frame and bolt a SS bolt to the frame....

This idea sounds good. I do not have access to welding so drilling a hole for a stainless steel machine screw should be good. Dielectric grease will help create a solid electrcal connection and the SS parts will not rust. I like attaching both the AC and DC ground wires at this point too, as I want to have a good trailer frame connection for both. That will be easy in this case because my running light and forward AC junction boxes are close together.

Bill

Bill, just for infomation purposes, dielectric is by definition, non conductive. The dielectric grease will block oxygen from the connection and prevent oxidation and increased resistance, even add a little water resistance to the connection, but it will in no way improve the initial electrical contact. There are conductive greases containing silver or carbon which are conductive and are used to impove electrical connections. They are used on some high voltage connections as well on connectors which are exposed to temprature extremems to help maintian contact between shrinking/expanding pins and blades. You do not need them on the trailer ground, the dielectric grease will seve well in that application, just do not expect it to make any improvement in the mechanical/electrical contact. If anything it might degrade the contact if enough pressure is not applied to move it out of the way and allow the metal surfaces to contact each other (the grease is designed to move out the way a low pressure). Still I would make the connection good and tight then apply the grease to seal it up, if at all.