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Non-conductive fasteners. Anyone?

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Axle Roads

New Member
I built a non-conductive bracket from aluminum and rubber to house a 350 amp battery disconnect switch on my classic car. The car is negatively grounded and the switch supplies positive current. I drilled two holes in the bracket to match up with two preexisting holes in the engine compartment. The problem is in how best to connect the two without risking an accidental short. I was about to use two standard steel bolts as fasteners, but obviously this would present small risk of short if a I accidentally bump an O-ring connector to a bolt or nut.

I thought someone here more familiar with electrical equipment might be able to identify the right fastener for this job. It needs to be removable, so no glue. Plastics are OK, but it should be durable and somewhat strong. A tie-wrap would allow too much moisture from the wheel well to enter the equation. Should I go with PVC, Nylon, Titanium? Anyone know of something I can pickup at the local hardware store?


New Member
Anyone know of something I can pickup at the local hardware store?
At the risk of sounding obvious, why not go there and see what they have, and ask for suggestions? Also, an auto mod shop would be a good place to check.


Well-Known Member
what about a short length of hose-pipe (or other rubber pipe) on the bolt as a 'bushing'. The pipe should be long enough that it is compressed slightly when the bolt is tightened. A rubber washer under the bolt head may also be needed.

Axle Roads

New Member
I'm worried those nylon screws will become brittle and fail in a few years time. But, I'm not sure. Does anyone here have experience with these? I can get a hold of these pretty easily.

I like the titanium bolts I see online from Chinese exporters, but I don't want to put my project on hold any more than the time it takes for the rubberized paint to cure (24-48 hours). So, it doesn't have to be from the local hardware store, just no obscure, online only, ten days to ship warehouses.

I like the rubber bushing idea. Maybe something like those blue drywall screws which expand and grip the wall; only it would have to be shorter and without gaps. A prefabricated options would be nice.

It's a simple problem. It likely has a simple answer, I'm sure there's a right way to go about doing this, it's been done a hundred times. I thought I was overlooking something obvious.


Well-Known Member
Most Helpful Member
TItanium is still conductive isn't it? Can you trust the oxide coating for insulative purposes? Personally, I don't think so.

Won't nylon only become brittle in certain chemical conditions? I don't know what conditions you are using but exposing them to threadlocker will make them brittle.
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I thought Nylon held up pretty good over time? They're very chemical resistant, when I worked in a plating shop we would run hex nuts with built in nylon washers through our entire chemical process without harming them. Not entirely sure about the long term though.


New Member
I have worked with aluminum X-ray pallets that had nylon screws to fasten UHMW polyethylene details. The shear strength of nylon screws is very low. Would it be possible to modify your enclosure with insulating bushings for the mounting holes? Also, Stainless steel screws would resist corrosion better. Aluminum + steel + moisture and dirt = galvanic action. If you cannot find what you need locally, try McMaster-Carr.

Best Regards
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