Where did they get the inspiration to start making us drive 2 ground rods??? Just had to do it the first time since code change in my area, and wouldn't you know it, the house is built on granite rock I think. I hit rock about everywhere I started. Finally got them to go down a little at a time... Hardest ground rods I have driven in 31 years and I had to drive 2 of them.. (the hard way with a pole driver and sledge hammer) What a work out... wonder if it is really necessary???

Hey SparkyNC:
250-56 was in the '99 NEC...not to mant people paid attention to it.
It's being enforced in this area now (NJ).

The choices that you have are to provide "documentation" to the AHJ that one rod tests 25 ohms or less...OR drive a second rod. No testing or documentation is required if two rods are driven.

The "tester" is about $2500-$3000 toy, and there is a lot of instructions to read to perform the testing. You could "just" hand a document to the AHJ, but if he requests proof...????. OR last but not least you can drive the second rod!

For what it's worth, my guys use a B&D Hammer Drill to drive the rods. (Macho 4)

John

everyone feels the need to build on a mountain here*, so the blasters get the biz.

I usually try for a Ufer , if i'm in the 'loop', and rods commonly go in the service lateral ditch...

*there is no 'flat'.....just up & down

Hey SparkyNC
Here is another way to look this. To prove that you have 25ohms or less to ground, you would have to drive a second rod to get the readings between them. Here in Georgia, we have to drive two rods also. I choose to drive them right below the drip line of the roof. Because of the moisture falling off the roof there, you're more likely to get a better ground for your grounding electrodes ( not to mention that the ground will be softer there too)!
Also, try driving your ground rods at about a 45 degree angle. The NEC will allow up to 45 degrees on your rods. And last, I use a Bosch hammer with a ground rod bit to drive my rods. Not only wil it drive through rocks with ease, but it will also stop the end of the rod from mushrooming... thus allowing you to put your acorn clamp on after the rod is driven. The3 only downfall I have encountered has been the electrical inspector questioning me if I cut the rod off because the end of the rod looks new after I drive it.
Good luck, and I hope this will help you!

This is not a new code rule. The 25 ohm rule is in my '78 code book. 250-84.
Don

Unfortunately, the 2 rod rule wasn't enforced until recently in my area.

When Allegheny Power came into town, services went up in installation price 50 to 100%!

I am NOT complaining!

GEC-1
Every ground rod I have seen lately has listing marks on the top. You can expose this for the inspector to prove you didn’t cut it.

in va if the incoming water pipe is copper then you only have to drive one ground rod, thats something i always look for before driving ground rods

Crlnva,

Does VA adopt the NEC into law? If so, then you would still be required to drive a second ground rod if one will not provide the 25 ohms or less to ground as specified in section 250.56, regardless whether the waterpipe primary electrode is copper or not.

Because the average electrical contractor doesn't own the special testing equipment required to measure ground resistance, most electricians will just drive the second rod to satisfy the requirement. Matt

va is still using the 96 code so maybe that is why, all I know is that I have been present for many inspections of service upgrades and the grounding to the water was good enough

I just happened to be working outside today and I had a spare ground rod in my garage so I figured I would add a second ground rod to my house.

When I dug up the first ground rod, I was surprised to find that the bronze clamp on the ground rod had eroded.

Makes one think a bit doesn't it.

Here in NJ the inspectors are not only asking for 2 ground rods but the state is requireing a ground rod in the footing of new buildings. (UFER ground) This new ground rod is inspected by the building inspector on the footing inspection. There needs to be a rod in the footing 1/2" or larger and 20 feet or longer, with an approved ground lug and # 4 cu wire long enough to reach the service panel or cold water pipe.

Harold

Crlnva,

I believe it is probably just ignorance of this section of the NEC by your local authorities. As Don has already stated, the requirement to add a second rod if the first one does not measure 25 ohms or less to ground is not new. My oldest code book is a 1975 version, and its in there bigger than ever in section 250-84 (now 250.56).

The requirement for a supplemental electrode to the waterpipe has been there as long as I can remember also, and is still a requirement today. You must always install a supplemental grounding electrode in addition to the metal underground waterpipe as required in 250.53d2. It doesn't neccesarily have to be a rod, but it does have to be one of the other types listed, (ie. metal frame of the building or structure, concrete-encased, ground ring, rod or pipe, or plate).

This requirement was there in 1975 as well. It is at the end of the paragraph in section 250-81. In the 1999 code it is in section 250-50a2. I don't have my copy of the 1996 NEC here at home, but you can rest assured, its in there too.

Unless at the time VA enacted whatever version of NEC they are currently using into law, they elected to exclude these specific sections of the code, your local authorities are either ignorant of these requirements, or they have overlooked them.

[This message has been edited by Matt M (edited 12-16-2002).]

I saw a neat one today at a friend's house. The service looked very new. I don't know the name of the electrician, but WOW that was a nice job.

(My wife just shakes her head when she sees me typing stuff like that...)

What I found peculiar was that one of the ground rods was inside the house, driven on an angle. (In the basement, of course.)

I just have never heard of that before.

[This message has been edited by ThinkGood (edited 12-15-2002).]

One more question/comment re: ground rods...

I would think that the water, gas and sewer lines are near-ish to where the electric service will enter.

Do any of you "call before you dig" (or rather, sledge, pound, etc.) -- have other utilities ever been victimized by a ground rod?

I'll bet that would result in some very foul language ;-)

Thinkgood,

I was on a job many years ago and I was on the job first. I installed the ground rod for the service, got instpection, passed and the service was hooked up. I went back for the final only to find that the Gas company ripped my ground rod out of the ground, installed their gas pipe, and never told anyone. If I didn't have to go back for the final, I would never have know about it. Plus, they installed their gas meter within 3 feet of the electric meter which is a violation to the power company here in NJ. (Maybe they should have called first!)

Harold

Come to find out one of our counties require the two ground rods and the county I live in and do most of my work in, don't require it now Sometimes it's hard to determine exactly how to do a job, when different counties haven't got the same procedures. But I'm not complaining I'm reasonably sure that just one of the two ground rods I drove last week, had to have the 25 ohms requirement, I had a sore neck and arm and a broken sledge hammer to prove it