Ground Rod At Second Panel Required.

Status
Not open for further replies.
M

martinelectric2

Member
Location
San Diego
I am working on a new home here in San Diego, CA. The house is built on a hill so the front entrance is at street level and the garage is detached from the house and accessed from an alley. The main services come from the alley, run through the garage and to the house. The garage and house are about 20' apart. The copper water line runs through the garage and then down to the house. The 200A service is on the corner of the garage and is grounded to a ufer and water pipe at the garage. A four wire run (2 hots, neutral and ground) are run to a sub-panel at the house. The sub-panel has the equipment ground bar and neutral separated. The inspector is asking for 2 ground rods and a water pipe ground at the sub-panel location. My question is, since the copper water line (buried in the ground from garage to house) is continuous, doesn't this qualify as a continuous conductive path and tie the two structures together as one?
 
The fact that the water pipe is common to both buildings doesn't matter what matters is each structure needs its own Grounding Electrode System, and when the waterline is part of the GES it needs to be supplemented, usually that means a couple of ground rods.

Why is there a ufer at the garage but not at the house?
 
As Dave stated you have two separate structures ans each needs it's own GES. The water pipe alone is not a GES at the house so you need to supplement it with another electrode which could be one rod, (if it's proven to be at 25 ohms or less) or two rods.
 
ActionDave said:
The fact that the water pipe is common to both buildings doesn't matter what matters is each structure needs its own Grounding Electrode System, and when the waterline is part of the GES it needs to be supplemented, usually that means a couple of ground rods.

Why is there a ufer at the garage but not at the house?
Click to expand...

Architect/builder didn't bother to check with an electrician before he built the main structures
 
infinity said:
As Dave stated you have two separate structures ans each needs it's own GES. The water pipe alone is not a GES at the house so you need to supplement it with another electrode which could be one rod, (if it's proven to be at 25 ohms or less) or two rods.
Click to expand...


Should the sub-panel also be bonded to the same water-pipe? Doesn't that set-up parallel paths, since its the same water pipe?
 
martinelectric2 said:
Should the sub-panel also be bonded to the same water-pipe? Doesn't that set-up parallel paths, since its the same water pipe?
Click to expand...

The neutral in the sub-panel is isolated from the EGC system so there is no parallel path for the neutral current if you connect to the pipe at both locations.
 
martinelectric2 said:
Thanks for the input, looks like i will be driving two ground rods (the inspection authority makes it difficult to allow just one)
Click to expand...

Yes two rods are required unless you want to spend the time and money to prove that one rod gets you down to the magical 25 ohms or less.
 
Status
Not open for further replies.
Top