I have a well & replaced the "water pump pressure switch. I connected it to the galvanized water supply with a 4" 1/4 copper (threaded both ends) pipe.
Will I have any trouble with the different metals (electrolysis, I think is the term)

(electrolysis, I think is the term) And that's what you don't want to happen. You prevent it by installing a ielectric union. Good luck, Tom

Im betting that nipple is brass, not copper. If so, no need to worry, I have seen this many times on well systems. I have never seen a 1/4 inch dielectric union on a pressure swith nipple.

I connected it to the galvanized water supply with a 4" 1/4 copper (threaded both ends) pipe. I go along with Lee on the Copper nipple, And I also question a 1/4" water supply line but I still go with installing a dielectric union. Regards, Tom

Tom, I believe sophie is merely speaking of the 1/4 inch brass nipple that connects the pressure switch (I think you call it a control box) to the pressure tank tee or other area of the water line near the pressure tank. I would agree, a dielectric certainly wouldn't hurt a thing here, but I don't think it is really needed.

FYI: Technically speaking, even brass nipple won't prevent electrolysis...

Milo

I completely agree, Milo. I have heard of people using brass as a "dielectric" between copper and galv. Only real way to prevent the electrolysis completely is the use of an actual copper to galv dielectric union.