Master ground?

[hampstead38]

Is there a master 12v ground on the '67 Overlander? If not, what do you think about creating a master ground onto the frame within the access panel area? Maybe I'm warped by my 110v experience, but I think residential main panels have to have three separate grounds. I was thinking a (possibly additional) master ground wouldn't hurt.

[69AmbassFl]

On my 69 Ambassador the ground side to everything is fused, so I would figure a master ground would eliminate this feature.

[markdoane]

I think the more grounds the better. I bolted grounding bars to the body ribs in three places, at the umbilical entry, at the main battery, and at the main 12V distribution panel.

Then I ran redundant #6 grounds between all three locations. Each grounding bar also provided plenty of ground points for the nearby devices.

So I would vote for multiple linked points rather than a single master ground.

[richinny]

i like the idea of a master ground so you can make one location that is easy to service and check. one other thought is to also ground that line on the opposite end of the trailer frame.

with seperate grounds, keeping a list of where each device was grounded, might come in handy.

[hampstead38]

I'm not Mr. Wizard when it comes to electricity, but my thought is that multiple grounds create redundancy. If you have one grounding point, it's easy to maintain, but a failure there shorts the system. Multiple redundant grounds allow for a single failure while maintaining circuit continuity... or so I would guess.

[vhord]

It is ironic that you brought up this point. I spent the last two days attempting to sort out my wiring. Like you I have a lot of experience with 110V systems and on Airstreams that is pretty straight forward. However, on the 12V systems I was confused why the manufacturers ran so many ground wires (white) from the converter in the rear to the front of the coach. It seems to me that this was a waste of material, created confusion in the wiring loom, and made it more difficult to diagnose problems. That is not the way you would wire the typical trailer. My only thoughts were that maybe it had something to do with electrolysis problems if a circuit lost a ground. I do not have a lot of knowledge about that. Any thoughts on this? Could you eliminate some of the grounds?

[Ramp]

If Airstream used hardwired grounds for all the loads it must have been for a good reason as it would be much more expensive than useing a frame ground as in an automobile. I know that if you join two different metals (steel and alum.) for example and run a current trough the juction heat is transferd from one metal to the other untill the juction is destoryed.

[vhord]

Originally Posted by Ramp

If Airstream used hardwired grounds for all the loads it must have been for a good reason as it would be much more expensive than using a frame ground as in an automobile.

I was not really suggesting that they use a frame ground. I need to count them tomorrow but they ran several (maybe 8-10) white ground wires parallel from the converter to the front of the trailer. Since approx. half of the 12V circuits are in the front it seem frugal to place a ground bar in that area to supply all of those 12V systems - pump, furnace, control panel, lights, reefer, radio & etc.

[hampstead38]

Well, the '67 Overlander has aluminum wiring on the 110v side. That's enough for me to question the perfection of Airstream's electrical engineer(s). Unless you wanted to create isolated grounds for each circuit, why not just run one heavier gauge common ground and use a ground bar where needed? Maybe Airstream got a great deal on bulk white-coated wire? I'm sure someone savvy in the ways of 12v electrical can explain this.