AC Panel Grounding Strip

[steveirving]

Hi Folks,

A few questions regarding the wiring of my trailers AC system...

Should the metal AC box be bolted directly onto the interior aluminum skin, or is it better to attach it to a wood backing which is then attached to the skin?

Should the grounding bar inside the breaker box also be attached to the interior skin of the trailer? Or just the metal breaker box?

Steve

[ventport]

The metal skin of the AS should be grounded to the uninsulated copper wire and grounding bar in the breaker box. The white wire should not be grounded.

[JimCat2000]

Good question, and I'm in the same stage of remodel...the 110v shore power.


My question is: How is the trailer truly grounded while under 110v shore power?


But I'll try and assist you with what little I do know.


I kept my original breaker box and we photo documented every attachment. My original 30 amp shore power connection had three 10 gage wires running from the exterior female plug to the breaker box; a black, a white and a yellow. The yellow was attached to the interior aluminum skin of the trailer via a ring terminal and metal screw. The black connected to the load side of the breakers using a jumper to hit both breaker busses. The white was attached to the common neutral within the breaker box.


The box was bolted to the interior skin, but the common neutral (white) is actually insulated from the box. It provides a direct neutral across each breaker. I test circuits by attaching a 6v battery using 3ft alligator clips to various wires, leads, etc. Then I trace the circuit using a cheapo voltage meter ($4.99 Harbor Freight). In this case, if I attach one clip to the black wire in and one to the white wire in, I read 6v across the breakers and 6v across the common neutral. But if I move my neg lead to the actual box, I get 0 volts telling me that the box is insulted from the common neutral.


So, I'm guessing that the ground in 1959 was supposed to be via the leveling jacks, or the tongue jack. It might not hurt to carry a ground rod attached via clamp to the frame and just hammer that thing in when you make camp!

[J. Morgan]

A modern ground for a trailer will be provided by the middle prong via the properly wired shore connection,

A metal rod wouldn't hurt.. But it would suck making camp....

I think the old campers included a grounding lug on the frame for just this though.

[JimCat2000]

Originally Posted by J. Morgan

A modern ground for a trailer will be provided by the middle prong via the properly wired shore connection,

A metal rod wouldn't hurt.. But it would suck making camp....

I think the old campers included a grounding lug on the frame for just this though.

So, maybe I shouldn't be using the original 30 amp shore power receptacle. .. this is what I ended up with (see pic). I ran new 10g wires across the breaker and fastened the green to the skin. The bare coppers are ganged-up and connected to the box fastener.

I'll get my neighbor/electircian to look at it this weekend.

[scamp]

You would never mount your metal a.c panel directly on the aluminum this will cause corrosion , your service a.c . Panel should be grounded with a aluminum clamp to the aluminum skin of the trailer also frame of trailer should be grounded you must follow aluminum wiring guides for house wiring from copper to aluminum .and use proper anti corrosive paste for dissimilar metals,house wiring is black hot wire,white neutral wire this is usually internal connected in service panel to ground , green or bare wire copper ground, on a trailer it looks like yellow is ground according to a previous post ,I don't have the info on this and if you have 220 volts the red wire is also hot wire,remember this is house wiring

[ventport]

In a trailer NEVER connect the white wire to the same buss bar as the copper or green grounding wires. If you do, your ground fault breakers will not work. They need to be kept separate in a trailer.