Tips for under-sink electrical safety that nobody talks about

I acutally just finished a similar setup for my new Insinkerator and a Pelican RO system, and mounting the box high is the way to go. I initially thougth about just leaving the existing Romex coming up through the floor, but after seeing how much water pooled when I replaced the P-trap, I moved the box about 16 inches up the side cabinet wall. I used a 4-inch square metal box with a raised industrial cover. One thing I ran into was how cramped it gets once you have the drain lines and the RO tank in there. I ended up using a Legrand Radiant GFCI beacuse it’s a bit shallower than some of the older Cooper models, wich made a difference in a shallow surface-mount box. I also used some plastic cable clips to keep the disposal cord pinned against the back wall so it wouldn't snag on the cleaning supplies we shove in there. I didn't go with a damp-rated cover, just a standard faceplate, but I definitely see the logic for it. Even if you don't have a major leak, the humidity under a sink can get surprisingly high if you have a slow drip you haven't noticed yet. Getting that outlet off the floor is probably the single best thing you can do for long-term safety in a kitchen.

You also need to ensure that the final installation maintains 'readily accessible' status for that GFCI per the NEC, becasue if you obstruct the receptacle with a massive multi-stage filtration tank to the point where you cannot reach the reset button without a plumbing teardown, you have essentially bypassed the safety intent of the code. Additionally, while the previous poster mentioned metal boxes, it is imperative to verify that you are utilizing a proper 10-32 grounding screw to bond the box to the equipment grounding conductor rather than simply assuming the mounting yoke provides sufficient continuity, as a loose device coud compromise the entire grounding path in a high-moisture enviroment.

Have you ruled out the risk of condensation dripping from the cold water lines or the faucet shank? I get the logic of mounting high to avoid pooling, but sometimes putting the box right under the supply valves just trades one problem for another. If a supply line develops a pinhole spray or the faucet gasket fails, a high-mounted box is directly in the line of fire.

Also, are we sure a metal box is the best move here? I've seen plenty of those get nasty with surface rust in humid cabinets long before an actual leak even happens. Did you consider using a PVC junction box instead to avoid the corrosion issue long-term?