this job is in Massachusetts, residential home, upgrading a service to a 200 amp, installed my 2 supplemental grounds outside, there's an existing ground rod below the panel which I will bring a #4 copper wire. My question is this. All the copper piping and water meter in the house is feed by a piece of plastic piping coming out from the basement floor from the street. Do I need to bring a wire from the panel to ground the copper piping ? If so what size? The meter is 30 feet away, the copper piping comes over to the water heater where the panel is , can I ground there? Thank you
Water pipe grounding
- Thread starter Eagle126
- Start date
- Status
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
if you have plastic coming in from outside and copper throughout the house then run a #4 to the water pipes at the closest location.
btw #6 is all you need for the ground rods
btw #6 is all you need for the ground rods
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Since you do not have a water pipe electrode you do not need to connect a GEC to the water pipe, however as Dennis has stated the metallic interior water piping system is required to be bonded. That bonding requirement is in 250.104(A) using table 250.102(C)(1) at any convenient point on the water piping system.
I read the complete article and know realize that a #6 copper wire was all that was required. Know I understand that I need to ground the water piping system that has the plastic coming in feeding the water meter, since it's not a true grounding electrode can I also install a #6, I see you mentioned #4, can you explain, thank you
- Location
- Bremerton, Washington
Yes, this issue has come up before. There is a difference between Table 250.66 and Section 250.66.
mortimer
third party inspector
- Location
- New England
- Occupation
- retired
you can use #6 copper to ground rods for any size service.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Table 250.66 tells you what size conductor to use for a grounding electrode. Normally that would be needed for all electrodes but there are some exception. One of the exception is that a #6 is all that is needed to the ground rod.
If the water line is an electrode then T250.66 comes into play and usually that is a #4 for a 200 amp service but the size of the grounding electrode conductor is based on the size of the service conductors.
If the water line is not an electrode and there is copper throughout the house then the copper line need to be bonded based on T250.102(C)(1) which is very close to the same as T 250.66-- thus a #4 would be needed in most cases for a 200 amp service
My reference to 250.104 is not pertaining to grounding, the OP has clarified that the water pipe does not meet the criteria of being an electrode so it only needs to be bonded which could be accomplished with the EGC of a branch circuit.
I think the OP knows a #6 is all that is needed for a rod after he read 250.66
Roger
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
No minimum size?
kwired
Electron manager
- Location
- NE Nebraska
Unless it has changed over the years, it must be size of the GEC to the interior metal piping system. Had to change that once when GEC would have needed to be more than 6 AWG even though the only electrode I had on that one was a CEE with the max required 4 AWG run to it.
My understanding for 6 to rods (and pipe electrodes) and 4 to CEE's is that those electrodes have been determined to not be able to dissipate any more energy than the respective max size conductor can deliver to them so there is no point in running larger conductors to them. Surprising copper industry people haven't done studies to prove this otherwise:blink:
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