Ground Rod Location

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tkb

tkb

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Location
MA
Can ground rods be located inside the basement of a house, or must they be located outside?

The house has a concrete sidewalk and driveway on the service side and it is not practical to locate the rods outside.
 
you could even be creative, and incorporate them into some strange feature of the house... such as a 'grounding tent' for the kids to play in, or a wierd looking sculpture perhaps..
 
Is deeper better or not.

Is deeper better or not.

tom baker said:
Yes they can be inside but its better to have outside and out past the drip line of the roof.
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We keep being told that the lower the impedance of a grounding electrode is the better off you are. If that is true then driving the rod through the basement floor is better than any place outside the home. Our best chance of getting below the permanent moisture level is to drive the rod as deep as we practically can. Trouble is that I am recently informed that lightning will not flow in deep electrodes but discharges it's current very close to the surface. So if we are looking for lightning protection we should use a ground ring but if we want to guard against a power cross or transformer core puncture deeper is better. Can anyone provide an authoritative answer which is better for electrical service entrance grounding?
 
Interesting that the general consensus seems that a rod in moisture is better than not. The NEC in 250.53 (A) states "Where practicable, rod, pipe, and plate electrodes shall be embedded below permanent moisture level. Rod, pipe, and plate electrodes shall be free from nonconductive coatings such as paint or enamel."

Anyone care to decipher this?
 
electricmanscott said:
"Where practicable, rod, pipe, and plate electrodes shall be embedded below permanent moisture level. Rod, pipe, and plate electrodes shall be free from nonconductive coatings such as paint or enamel."
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The rod should be below the (top) of the permanent moisture level, i.e. installed such that some or all of the rod be below the water table so it remains in moist soil as much as possible, for better conductivity/lower resistance. And the rod should not be coated with materials that electrically insulate it, for obvious reasons.
 
electricmanscott said:
Interesting that the general consensus seems that a rod in moisture is better than not.
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Do you disagree?

Anyone care to decipher this?
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"Where practicable, rod, pipe, and plate electrodes shall be embedded below permanent moisture level."

I believe the "permanent moisture level" is like a flood plain. Just a line. I don't believe they're asking for the electrode to be underneath the permanent moisture zone. I believe that would be in the core of the earth somewhere.

"Rod, pipe, and plate electrodes shall be free from nonconductive coatings such as paint or enamel."

Since ground rods are not required to be listed, then the NEC is tossing out some rules to cover those.

Or am I missing your point entirely? :D
 
georgestolz said:
"Where practicable, rod, pipe, and plate electrodes shall be embedded below permanent moisture level."

I believe the "permanent moisture level" is like a flood plain. Just a line. I don't believe they're asking for the electrode to be underneath the permanent moisture zone.
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You may be right I really do not know. :)

IMO what they mean is the rod should be installed under the normal water table.

At my own home that would be only about 18" under my basement floor.

I did a job on Massachusetts's Cape Cod which is pretty much a sandbar into the ocean, on that job a 20' ground rod was used in order to hit the permanent moisture level. Dry sand is not very effective.

Do I think anyone normally does this?

No.
 
I neither agree nor disagree and I don't really know that I have a point. :lol: Can't say I am sure what the meaning of the requirement is. Based on the wording it seems that whatever they are saying you must do does not really matter much. Take any installation and say it was not "practicable" to do it so I didn't.
 
I picture the "permanent moisture level" for a given spot as being, the depth at which you find easy digging with a shovel when digging with a shovel. Around here, if you can dig it, the soil tends to get moist about a foot deep, give or take.

A sprinkler system would taint that definition, because the moisture really begins at the surface in the summer months when it's in operation.

I view this as different than the water table, which could be very shallow (as evidenced by looking in the sump pit in some of the houses around here). The water table, IMO, is where you find standing (or flowing) water when you dig.

Do I install ground rods under the line I would call the permanent moisture level? No. I can't even stand behind the defense that I could call it "impracticable", since I could generally dig down a ways where I'd install a ground rod. I just don't see the point in all that work, and it's never practiced around here.

A bit hypocritical of me, I guess, but the common practice trumps the code in this case. :oops:

In fact, some folks would actually fail a buried ground rod, for reasons I can't understand. If the copper is okay in the soil, and the ground rod obviously is, and the connector is rated for direct burial, then there's no reason the top of the rod can't be a foot deep. But some will claim the connection has to be accessible, despite an exception to the contrary.
 
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