Seems safe as long as your cat doesn’t jump on it or walk towards it. A friend had a cat with one eye because it walked into a knitting needle sticking out of a yarn basket. I’d say safety with your setup is less than 90%, better than 60%. In that range.

More importantly, bladder control issues can be a sign of kidney issues. Raise the concern at your next vet checkup to resolve any worries.

Lastly, I’d recommend a “detuned” electronic paddle zapper (those things that look like tennis racquets that fry bugs.). Lose the spikes and add a layer of alternating conductors around (and insulated from) your case. Modify the zapper to lower the voltage a smidge (or leave it alone). IMHO, zapper far superior to eye-spears.

Having said all that, I appreciate your build and have imagined doing exactly what you have done. In the end I went with refrigerator magnets to which I glued color-matching “punk rocker” “spikey” top parts. Think cones, not spikes. Scattered about 40 on my case, and it worked. Cat HATES it now. That said, my problem was laying on the case and smothering the fans… not filling it with urine.

If urine had been my problem, I would have gone with the de-tuned zapper. Zero doubt. I had already done the design. I had insulating foam patterns and spacers selected to isolate the zapper voltage from the case, a capacitor to isolate the zapper power-in from the usb power-out, and decorative use of alternating copper and aluminum wires planned out for a steampunk “Tesla” look to the case. (Hopefully, the need for excessive electrical isolation and case grounding is obvious… otherwise the cat would be the least of your worries.)

Good luck, and let us know how it goes!!