Ask Me Help Desk - Union to the main water line outside

Quote:

Originally Posted by bekerocha

Please tell me the purpose of a union main?

A dielectric union is used on the direct buried metal pipe to prevent back feed of any residual electrical fault current to the main pipe system if the fault does not have proper electrical equipment grounding inside the house... or... if the water pipes inside the house have been converted from galvanized piping to copper piping. The union prevents having an electrolytic degradation to the remaining galvanized pipe. That would take a little while before the joints start to leak but it will happen.
Does this make sense? Nm :)