How to Attach Ground Wire to Frame?

[B52]

[quote="madjack
yep, that is how it is done on my boat trailer and so far, 13yrs and no light problems............. [/quote]


When was the last time you actually hooked that trailer up to check those lights?????

[wlooper89]

This looked to be the best products available at the local hardware store for my small project. It should be a big improvement over the present arrangement. I probably only need one grounding post but they came in packs of two.

[cokebottle10]

What you have in the photo looks good to me, But I think that you will need to have star type lock washers on both the bolt and nut. They have alot of teeth and will cut into the metal. Use the die-electric grease to keep the corrosion away. The washers will cut into the bolts, metal and nuts to make a good connection.

Thanks,
David.

[Dale M.]

Contrary to all know mechanical connection knowledge in universe, a star (tooth type) lock washer between ground connector and frame is best possible way to insure a good mechanical connection.... Forget chemical rust stripper and use rotary wheel (grinding) on electric drill to find clean fresh metal.....

Dale

[wlooper89]

Contrary to all know mechanical connection knowledge in universe, a star (tooth type) lock washer between ground connector and frame is best possible way to insure a good mechanical connection.... Forget chemical rust stripper and use rotary wheel (grinding) on electric drill to find clean fresh metal.....

Dale

Thank you for your suggestions. The place I want to put the grounding post is painted and not rusted. The grinder should be good on that to clean down to metal or perhaps start with a chisel. Attach the post then use primer and paint.

There are some rust spots in other places where I may try the Naval Jelly and then prime and paint. Have never used Naval Jelly and am interested to see how that will work.

Bill

[Miriam C.]

Contrary to all know mechanical connection knowledge in universe, a star (tooth type) lock washer between ground connector and frame is best possible way to insure a good mechanical connection.... Forget chemical rust stripper and use rotary wheel (grinding) on electric drill to find clean fresh metal.....

Dale

Thank you for your suggestions. The place I want to put the grounding post is painted and not rusted. The grinder should be good on that to clean down to metal or perhaps start with a chisel. Attach the post then use primer and paint.

There are some rust spots in other places where I may try the Naval Jelly and then prime and paint. Have never used Naval Jelly and am interested to see how that will work.

Bill

Be sure to sand after the Naval Jelly where you put your post. You get more than one grounding post because you might need one on each side and the front/back..........short runs tend to waste less wire and less chance of a break.

[wlooper89]

Be sure to sand after the Naval Jelly where you put your post. You get more than one grounding post because you might need one on each side and the front/back..........short runs tend to waste less wire and less chance of a break.

Thank you Miriam. Those are good ideas. I have just two wires to attach, both #10, one AC and one DC. But having each on a separate post may ensure better connections. And mounting them on opposite sides of the same attach point will save drilling a second hole.

Bill

[Miriam C.]

Be sure to sand after the Naval Jelly where you put your post. You get more than one grounding post because you might need one on each side and the front/back..........short runs tend to waste less wire and less chance of a break.

Thank you Miriam. Those are good ideas. I have just two wires to attach, both #10, one AC and one DC. But having each on a separate post may ensure better connections. And mounting them on opposite sides of the same attach point will save drilling a second hole.

Bill

You definitely want them on a separate ground. I am still not sure why some are grounding AC. Mine isn't and it works just fine.

[Arne]

basically, you need metal to metal contact, then you have to protect that contact from the elements/corrosion... pretty simple.

[wlooper89]

You definitely want them on a separate ground. I am still not sure why some are grounding AC. Mine isn't and it works just fine.

I will try to describe my reason for grounding AC to the trailer frame. In the beginning I did not have AC grounded to the frame and it worked fine that way. Then later I attached AC ground to my aluminum box electrical compartment. I believe adding a grounding post to the steel trailer frame will be an improvement. AC does work fine either way, grounded to the trailer frame or not. It is grounded through the power cord to the campground pedestal outlet in either case.

RV manufacturers do ground AC to the vehicle frame, and I believe it is in their wiring code to do it that way. DC negative can also be grounded to the trailer frame or not, either way is fine and does not interfere if both AC ground and DC negative are attached to the frame. Usually the vehicle frame is used as negative for the 12V running lights, probably to save wire.

This is one possible case where grounding AC to the trailer frame could be a plus, especially in my setup with a metal electrical compartment attached to the trailer tongue. If AC hot or neutral shorts to the trailer frame nothing would trip right away if the frame is not connected to AC ground. But if a person standing on wet ground touches the trailer frame the person could receive a shock. A GFCI, if installed upstream of the short, should trip in this case and prevent injury to the person. If the same short occurred with AC grounded to the trailer frame the GFCI would trip immediately and not wait for someone to touch the trailer frame standing on wet ground. I like the second scenario a little better, having AC ground attached to the trailer frame as an RV manufacturer would do, but in either case a GFCI will protect the person if it functions properly. Having AC ground connected to the trailer frame could give earlier indication of a short between AC hot or neutral and the frame, allowing for earlier troubleshooting. Additional thoughts or opinions are always welcome.

Bill

[BC Dave]

Bill good explanation! full marks on the why to ground AC.

I'm just in the process of installing AC; I ended up grounding the main inlet and the first GFC outlet that all others are connected to (so all outlets are GFC through the first, great suggestion from another TDer).

I used a medum-small bolt; toothed washer & bolt through a drillled hole in the frame; scraped to bare metal; tightened good & tight ...THEN ... used another 2 toothed washers to sandwich & squished the copper wire with a second nut; seemed to work quite well; oh and used liquid electrical tape to paint over.

My 2 cents on AC grounding

Cheers BC Dave

[wlooper89]

Bill good explanation! full marks on the why to ground AC.

I'm just in the process of installing AC; I ended up grounding the main inlet and the first GFC outlet that all others are connected to (so all outlets are GFC through the first, great suggestion from another TDer).

I used a medum-small bolt; toothed washer & bolt through a drillled hole in the frame; scraped to bare metal; tightened good & tight ...THEN ... used another 2 toothed washers to sandwich & squished the copper wire with a second nut; seemed to work quite well; oh and used liquid electrical tape to paint over.

My 2 cents on AC grounding Cheers BC Dave

Thank you BC Dave, I would like to add that there is a lot of variation in teardrop AC electrical systems. Sometimes all one wants is a power strip plugged into the cord from campground power. I have seen one such power strip with a built-in GFCI that some forum members use. In such cases it is probably not necessary to ground AC to the trailer frame.

In other installations where AC wiring is installed in the trailer that may be in proximity to the trailer frame, perhaps an AC ground to the frame is a good idea.

Bill

[southpennrailroad]

My cargo trailer is all metal and my porch light and inside light is grounded to the trailer frame. My battery is in the back on the floor near all the electrical outlets. I figured why should I not use the trailer as a ground and save on running an extra wire. I just ran a small short line to the trailer from the battery negative post.

[Engineer Guy]

I second the ideas above, especially cleaning to bare metal. When tweaking a pal's new/used Wildnerness hardside, the Stop lights alone were WAY weird. They flashed alternately from side-side-side. So, I tried to analyze it. He put on new Lights, especially since the '88 originals were kinda cloudy and dim. Problem solved. We redid the ground connections. He's a big fan, from the Machinist World, of this type of stuff. A Pro Electrician I worked beside always used this 'grease', especially on high current connections:

http://www.google.com/search?sourceid=chrome&ie=UTF-8&q=electrical+conductive+grease

On inquiry, a local RV Shop Wizard, who inherited the Biz from his Dad, told me that ~80% of what he corrects is due to intermittent ground connections, or related issues. 'Nuff said, since he's had his hands on more RVs than I ever will.

In my World, the frame supports weight. A separate ground wire provides the electrical return path. The two functions don't meet, other than always grounding the frame to put it at earth ground potential, DC or AC.

A Trailer on Rubber Tires and a Jack Pad is not grounded anywhere automatically. Should an AC short to chassis electrify it [water leak, etc.] and a person touch chassis, they're the only path to ground for umpteen surge amps. For any GFI to work, it references ground, so ground has to be there 100% of the time.

A State Code Inspector tells me he's seen false trip issues with GFIs connected in series. The way he suggested was one GFI, with other Outlets in series. End of story.

Electric Brakes, especially, ideally have their own ground wire to the Controller, and to an impeccable TV ground thereafter. Wonky/open Brake ground can equal no braking. Wheels Brakes draw ~3 Amps/wheel, but many Controllers are fused at 30 Amps to control 6 wheel Horse or 5th Wheel units. So, the hot and ground leads should be sized to the Trailer/future load.

Mag Chloride used here in CO for Road deicing eats connections, including TV ABS Brakes, for breakfast. Trailer connections are subjected to really corrosive conditions.

[Larwyn]

I agree with most of that, and ground both ac and dc to the frame. But it is my understanding that a GFCI trips due to a differential in current between hot and neutral, and will actually function quite well without a ground.