Bear with me on this, its early and I have not finished my 1st cup of coffee yet. The AHJ in my area always checks to make sure the primary ground is the water pipe and that we jumper the water meter, so if it is removed the service is still grounded. I am fine with that. The primary carrys the fault current back to the panel to help trip the breaker and all so back to its sources, which is the tranformer on the pole. What if in new construction they use plastic pipe for the water, that is from the street to the house. We always use one gounding rod in this area but other AHJ in other areas make us use two. What is the primary when there is no water pipe to use. Grounding rods are for lighting strikes and high voltages surges.
Primary ground?
- Thread starter guschash
- Start date
- Status
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
If there is plastic coming in from the street then you only need to bond the water pipes in the house if they are metallic. Otherwise, 2 ground rods per code unless you can get 25 ohms with one.
I don't believe a water pipe will clear a fault.
I don't believe a water pipe will clear a fault.
brian john
Senior Member
- Location
- Kilmarnock, Va
- Occupation
- Retired after 52 years in the trade.
If a cable falls against the water pipe and shorts then YES the water pipe will carry the fault current. In any other fault in the house the EGC (equipment grounding conductor and any other bonded metallic components)carries the fault current.
While the water pipe can play a roll in this with VERY low soil resistance, multiple houses connected to the metallic water piping, it really is not the main function of this connection.
Additionally (FOR ME) using the term primary ground is misleading as the terms primary and secondary have other meanings in the trade.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
brian john said:
Brian if the exterior water pipe is not connected to a bond will this water pipe still carry a fault. How is it any different than a ground rod--- assuming it is not connected thru someone else's system
- Location
- New Jersey
- Occupation
- Journeyman Electrician
brian john said:
I agree that the term primary ground is misleading and should be avoided when possible. If the house had a CEE and a water pipe electrode which would be the primary ground?
brian john
Senior Member
- Location
- Kilmarnock, Va
- Occupation
- Retired after 52 years in the trade.
I was thinking interior copper piping, exterior piping a whole lot of factors will play into how much actual fault current will be on this conductor.
How many houses are connected to the metallic piping, how many houses are on a common transformer.
How many houses are connected to the metallic piping, how many houses are on a common transformer.
- Status