# Bonding and grounding aluminum frame to steel trailer



## patrickdickey52761 (Oct 2, 2021)

This might not be the right place (or even site) for the question, but I'm going to ask. I'm considering building a small camper using a steel trailer frame and aluminum struts to frame out the walls/ceiling. Everything that I'm seeing says to isolate the two metals to prevent galvanic corrosion. They even include isolating it electrically.

Here's my issue and question. I plan on using radios in the camper, which means that everything needs to be grounded and properly bonded, to prevent RF interference. What would you recommend to do this? I'm thinking about copper wire bolted to both the aluminum and steel components using stainless steel fasteners. Would that suffice, or would it cause the galvanic corrosion that I'm trying to avoid? If it's not the ideal solution, I'd appreciate recommendations for how to accomplish this.

And if this isn't the place for my question, I apologize.

Thank you in advance either way. 
Patrick.


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## travis.farmer (Jun 26, 2021)

stainless and aluminum will cause galvanic corrosion. so will copper. the only metals i found not to react to aluminum is magnesium and zinc. but they do react with steel...
one option is to use a thick plate of aluminum to bond to the aluminum frame, and a stainless steel strap to bond the steel frame to the aluminum block, with a plastic fastener. this way you have two sacrificial metals (the stainless strap and aluminum plate) with a SINGLE point of contact. so you will only have one point of contact to worry about cleaning up every so often to maintain ground bond.

alternatively, just earth-ground the steel frame and aluminum to sepperate earth ground stakes.

contrary to this... if i remember correctly, if the equipment itself is in proper working order, and the antenna cable and connections are good, and all are properly grounded to the common ground buss, and to an earth ground stake, there should be no need to create a Faraday cage around the equipment. (i took and passed the ARRL technician exam, but never received my FCC license due to being a felon, from a bad mistake many years ago).

as per camper wiring, the battery ground and AC earth ground are generally bonded, as is the steel frame. the aluminum body is generally left electrically floating, depending on the OEM, with lighting run with both a ground and power. those that use an aluminum electrical ground seem to always fail to light at some point.

my best guess, make sure your equipment is bonded to a common ground, that is earth-grounded to a stake, deep in the soil. and also that your equipment is in proper working order. if concerned about the aluminum body, earth ground it independently with aluminum wire, and an aluminum stake driven deep into the soil.

~Travis


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## patrickdickey52761 (Oct 2, 2021)

travis.farmer said:


> stainless and aluminum will cause galvanic corrosion. so will copper. the only metals i found not to react to aluminum is magnesium and zinc. but they do react with steel...
> one option is to use a thick plate of aluminum to bond to the aluminum frame, and a stainless steel strap to bond the steel frame to the aluminum block, with a plastic fastener. this way you have two sacrificial metals (the stainless strap and aluminum plate) with a SINGLE point of contact. so you will only have one point of contact to worry about cleaning up every so often to maintain ground bond.
> 
> alternatively, just earth-ground the steel frame and aluminum to sepperate earth ground stakes.
> ...


Hi, Travis,

First of all, thank you for the information. And, I am probably overthinking this. As you said, as long as my equipment is bonded properly, it shouldn't matter if the frame and body are. Plus, most likely my antennas will be away from the camper or at least bonded to the steel frame. As for you passing the ARRL Tech, good on you. I think you should try again, as they are allowing more felons to get their licenses (obviously the circumstances will matter and I'm not asking). But either way, the fact that you passed it is great. And it makes you more helpful to me since you understand what I'm trying to do.

Have a great day. 
Patrick.


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## Tony K. Manley (Oct 14, 2021)

I always recommend a solution I know of for galvanic corrosion, a simple one. You'll need to have some plumbing snaking through the frame of your camper. In the bathroom, one or both of the sewer outlets is going to be accessible through a small 4 inch conduit. Connect the 4 inch conduit into a length of 1/4 inch plumbing threaded into the stainless steel bushing that will enclose the coupling.


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