I'm trying to help someone in Cuba to install a switch to control an electrical shower. The shower has a switch on the top that regulates warm, cold and hot water, but when the water flows thru the shower some water overflows from the top, when the person taking the shower wants to turn off the switch he can feel the electric current in the switch. I would like to install a separate switch away from the shower to control the on/off switch. I believe the resistance in the shower uses near 30 amps. What can I buy in the US to improve this situation?