I was wondering about the most effective residential service grounding method. Many use the domestic water piping (assume no plastic pipe/fittings in the lines). My concern with a copper piping system used as a ground involves possible electrolysis and slow damage to the pipe itself and the sweat joints. I have measured a small potential difference between the power company neutral and the piping ground. Could this small potential be a cause of electrolysis?
It seems the safest way to a ground residential system would be using a ground rod. Is there an effectiveness difference between the two methods? Any thoughts welcomed.
I have also heard stories, but have no reviewed references nor personal experience, that _AC_ current on the metal water pipes is much less of an issue than very small _DC_ currents on the pipes. This makes some sense, since AC would tend to redeposit any materials removed.
#61047 - 01/16/0603:38 PMRe: Ground Rod or Water Pipe Ground?
I use both a ground rod and the domestic water line. I also bond the hot and cold at the water heater to asssure complete bonding of the water system. This pratice gives all the residential water supply systems the same potential within the structure.
#61048 - 01/16/0603:43 PMRe: Ground Rod or Water Pipe Ground?
Dnk I am not interested in Hammering you but I am confused why you think the water line is optional.
250.50 Grounding Electrode System. If available on the premises at each building or structure served, each item in 250.52(A)(1) through (A)(6) shall be bonded together to form the grounding electrode system.
A metal water line is on the list, if it is there it must be used.
[This message has been edited by iwire (edited 01-16-2006).]
Bob Badger Construction & Maintenance Electrician Massachusetts
#61051 - 01/16/0608:04 PMRe: Ground Rod or Water Pipe Ground?