Gentlemen: This question concerns both application and safety(perhaps more) on direct Immersion Electric Heaters in a sump of a Cooling Tower. The Heaters are in direct contact with the water of the sump (cold water basin) to prevent freezing (typically 40 to 45 degrees). The sump areas are typically large enough to access through a door onto a cat walk. This places a worker directly above a sump area with a potentially charged (heater energized and failing) water source. Finally, my questions!! Is there a Megohm reading that the heater should pass to be considered safe, and does or should any type of code call for a specific type of breaker or fuse(circuit protection)for this application ?? More information available if required, thanks.
I think that qualified persons following a written safety procedure can do more to prevent accidents than anything else.
IMO, since you normally can't enter a cooling tower to do any maintenance without first shutting down the water pumps at the chiller location, you should also LOTO the circuits or disconnects for the tower heaters and make up water valve before attempting to clean the sump filter grates or perform algae and mold removal.