That sounds scary! These water heaters are actually very common in this part of the world, and if you can get past the idea of electric wires in (actually above) the shower they work quite well.
Hot water isn’t standard in Panama. There are many people who never had a warm shower in their lives. I’ve seen neighbors bathing the children outside with the garden hose. Of course this is the tropics and cold water isn’t especially cold. To me it feels like a swim on a hot day, maybe a second to get used to it and then it’s refreshing and really nice.
We have an on demand gas water heater on an outside wall with lines to the shower and kitchen. When I moved in a neighbor pointed it out as something really special. It’s temperamental though. You need to turn on the hot water and when it’s hot, then turn on the cold and hope you get something pleasantly warm for a minute before it turns totally cold. Repeat the process as needed. I quickly decided this was more trouble than it’s worth and just took cold showers.
The water heater stopped working. It’s been so long I don’t even remember when. New batteries didn’t help, and we didn’t care enough to try anything else.
Now though it’s the height of rainy season, and we’ve had a few very chilly days with little to no sun, and temperatures down to 70 at night. Ok, I can hear most of you laughing and rolling your eyes, but we are acclimated to heat and happy in the 80’s. This is why we don’t live in the mountains. We like it warm.
A long time ago we bought a suicide shower to help a friend. She ended up fixing the one she had so she didn’t need it. They are inexpensive enough that it wasn’t worth taking back to the store, so it’s been in storage. Then it dawned on us. If we don’t want cold showers on chilly days, we could get it out and install it!
These heaters draw quite a bit of power so always use a heavy duty wire. You can see the circles on the unit, black for hot, white for cold, and half and half for warm. Black tends to pop the circuit breaker, but warm with a slower water flow (less to heat) produces a very nice, comfortably warm shower. I don’t mind a cold shower at all but even I will admit it’s very pleasant to have warm water sometimes.
So, if you find one of these in a shower, don’t freak out. It won’t electrocute you. It will just give you some nice warm water.