2 ground rods???

stagger19

Well I had the inspector out today for my sub panel that Im putting in my garage. I wanted to get the trench inspected so I could back fill.

Anyways, he wants me to use (2) 5/8 by 8ft ground rods, spaced a min of 6 ft apart. I never heard of using 2 ground rods before.

Speedy Petey

Unless it is a local ammendmant, he cannot demand two rods.

But.......what he can do is ask for the test results from checking the ground resistance to see if the one rod measured within specs; 25Ω or less. This is NOT a test you can do with any old meter either. It requires an $800 ground resistance meter.

This is why most of us simply sink two rods and are done with it.

__________________
Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.

rforsha

We rewired our house in 1999 and setup a panel for electric heat. We had to install two grounding rods for the new service. We are in PA. and the national code required it.

Speedy Petey

The national code (NEC) does NOT require two rods.

See my second paragraph above, or NEC 250.56

Actually here it is:

250.56 Resistance of Rod, Pipe, and Plate Electrodes
A single electrode consisting of a rod, pipe, or plate that does not have a resistance to ground of 25 ohms or less shall be augmented by one additional electrode of any of the types specified by 250.52(A)(2) through (A)(7). Where multiple rod, pipe, or plate electrodes are installed to meet the requirements of this section, they shall not be less than 1.8 m (6 ft) apart.

__________________
Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.

fqp25

Sometimes it is best to do what the inspector asks. Inspectors municipal employees or private contractors usually are certified by the ICC, (International Code Commission). They have to at least pass 1 test to get this certification. However their background of experience and knowledge is usually not as much as a seasoned veteran.

So they might require a little extra to cover their own tracks.(so to say) After all a lot of contractors and craftsman say code is only the minimum you should do. After all, how could an extra ground rod hurt you? Except maybe $25 for material. Like the shoe company says "Just Do It"

Speedy Petey

Once you've had to sink a few extra rods in rocky soil you'll know how they can hurt.

Confidentially: I use a rotary hammer with a drive attachment.

__________________
Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.

HUDSONVALLEYEXT

you need two ground rods here in NY also an extra can't hurt

Speedy Petey

Two are ONLY required if the resistance is not met. See post #4.

Or if the POCO requires it. Such as with a pedestal service. Then it is a POCO issue and not an NEC or local building code issue.

__________________
Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.

buckeyefanted

The reason that some inspectors require 2, is that they dont want to meggar it, or they dont have the equipment, Most of the time when they require 2 ground rods its because you used aluminum wire.

rrolleston

Around here they require the same. Two rods at least six feet apart with #4 wire running from the panel to both rods then back to the panel. For what it costs it's not worth arguing with them.

concretemasonry

Local jurisdictions can always over-ride the national MINIMUM codes in any area of construction and permitting. This is based on the concept that the national standard is just a MINIMUM and there may be local natural (climate, soil, moisture, factors) conditions that justify it based on experience and performance.

the cost differences are minimal compared to the long term safety.

Dick

rrolleston

Probably due to the really sandy soil. During the dry months you could dig really far down and never see any moist ground.

Hardway

Ground rods on a sub panel???
What about ground loop???

rrolleston

LOL. Watched a few videos of them those are really nice.

Hardway

Are you feeding this sub panel from the house main?