I'm not sure if it's code everywhere, but Wisconsin requires the neutral be bonded to ground to prevent the  occurrence of everything taking a 220V hit if the neutral should fail. Makes sense to me considering neutral is at ground potential. 

1 hour ago, Larry Buskirk said:

neutral be bonded to ground

What does that look like Larry? Like a physical bond? A weld or something? Thanks

8 hours ago, Larry Buskirk said:

I'm not sure if it's code everywhere, but Wisconsin requires the neutral be bonded to ground to prevent the  occurrence of everything taking a 220V hit if the neutral should fail. Makes sense to me considering neutral is at ground potential. 

It’s in The NEC, but if that bond occurs in the meter socket, and the neutral lets go in the panel, well...... you’re getting 220 volts to everything in the panel. Doesn’t happen often, but enough that we are all aware of it.

7 hours ago, John Morris said:

What does that look like Larry? Like a physical bond? A weld or something? Thanks

In the meter socket (in this example), you bring the 3 wires (2 hots and a neutral), into the top of the meter socket. There are 3 terminals, 2 bring the hots into the meter when it’s plugged in, at the bottom there are 3 terminals, 2 coming from the meter, with the metered power to feed the panel. The top and bottom neutral connection are the same piece of metal. There is also usually a side terminal on this piece of metal for a ground. This is usually coming from 2 ground rods, but not always. These terminals are basically a setscrew connection. If these are loose, all sorts of bad things can occur, which I believe is what happened to John. If you have a metal water pipe from the street, or well, you get a back-up ground (even though the code states it as giving the home pipe system a ground). Grounds very important, tight connections a must.

Thanks for the great explanation Artie.

Artie beat me to it, but I did an additional ground at the outdoor panel when I rewired our house. This will probably sound like overkill to Artie but I started with a 200 Amp master panel which feeds two 100 Amp sub panels, a 75 Amp generator panel, and a 100 Amp outdoor panel on the rear of the house. I did it this way so I could wire the house in sections without having to run everything back to the main panel. The panels are located front, middle, and rear of house. In the Square D panels I used there is a spot on the neutral bars for putting a bonding screw that ties the neutral to ground. I have double ground rods front, and rear of the house. The front set of ground rods go to the main panel, the rear set to the outdoor panel. These two panels have the neutral bonding screws installed. I also installed a whole house surge suppressor in the main panel. 

 

When the building inspector checked the work he asked "Do you know the meaning of the word overkill?" 

The only thing he wanted changed was to add an additional mounting clamp to the drop pipe feeding the meter socket. I added two because there were two in the package. BTW the inspector passed both the electrical, and plumbing on the first inspection.

2 hours ago, Larry Buskirk said:

Artie beat me to it, but I did an additional ground at the outdoor panel when I rewired our house. This will probably sound like overkill to Artie but I started with a 200 Amp master panel which feeds two 100 Amp sub panels, a 75 Amp generator panel, and a 100 Amp outdoor panel on the rear of the house. I did it this way so I could wire the house in sections without having to run everything back to the main panel. The panels are located front, middle, and rear of house. In the Square D panels I used there is a spot on the neutral bars for putting a bonding screw that ties the neutral to ground. I have double ground rods front, and rear of the house. The front set of ground rods go to the main panel, the rear set to the outdoor panel. These two panels have the neutral bonding screws installed. I also installed a whole house surge suppressor in the main panel. 

 

When the building inspector checked the work he asked "Do you know the meaning of the word overkill?" 

The only thing he wanted changed was to add an additional mounting clamp to the drop pipe feeding the meter socket. I added two because there were two in the package. BTW the inspector passed both the electrical, and plumbing on the first inspection.

The trade is full of those who tell everyone else they’re doing it wrong, please don’t put me in that group. The only panel your supposed to install the bonding screw is the main panel, it’s not supposed to be done in sub panels, according to NEC. I remember having a discussion years ago on the whyfores of this, with an inspector, but alas can’t remember it. If anyone is interested I can talk to the towns electrical inspector, he sits on one of the code panels, so he’s very knowledgeable. You’re only supposed to have one ground per service, you can/must use two ground rods, but it is only 1 wire to them from the service. I believe one of the reasons is with multiple grounds you can actually be sending current over a ground, while under normal operation. In theory the neutral and ground should both be at the same potential, so in theory it shouldn’t matter, but it is one of conditions I’ve had checked by the inspector at every subpanel I’ve wired. Other than that the more panels the better  

@Artie,

I forgot to mention that the inspector had me remove the bonding screws in the indoor sub panels, which I did right in front of him. The specs in the code weren't very clear about the sub panels. The inspector checked his code book, and said that the ground to the outside sub panel was to code which surprised him. That was better than 15 years ago though so things might be different now.

Pretty much as long as the inside SUB panels don’t have the screw, no problems. In talked with a couple of the other sparky’s at lunch, and they also thought it was because you could get current on the ground wire, which could backfeed onto the building piping systems. We have long talks about grounding and the code, many gray areas, I just do what they tell me (what can I say, I’m married, trained well LOL) 

I don't know if it applies to all of Florida, but certainly here in North Florida, you can no longer use the water pipes as ground.  Too many houses since the 1970's have some form of PVC plumbing.  So, for grounding, they use two 6 foot long rods placed 3 feet apart with the same ground wire attached to both.  The grounding occurs at the meter box.  From the meter box to the transformer, it is the problem of the utility provider.

2 minutes ago, FlGatorwood said:

I don't know if it applies to all of Florida, but certainly here in North Florida, you can no longer use the water pipes as ground.  Too many houses since the 1970's have some form of PVC plumbing.  So, for grounding, they use two 6 foot long rods placed 3 feet apart with the same ground wire attached to both.  The grounding occurs at the meter box.  From the meter box to the transformer, it is the problem of the utility provider.

In Ma. The ground rods must be 6 feet apart minimum, 10 feet apart maximum. I HATE driving ground rods. When I started you got your ground from the water pipe, now for the very reason you stated we have to drive ground rods. If you have the expensive meter, and can prove 50 ohms or less resistance to ground, you only need one rod. No matter what the resistance is, two ground rods meets code. You still have to run a ground wire to the metal interior piping system, only instead of getting a ground from it, you’re GIVING it a ground. In a home with metal water utility pipe, this a crock of you know what. 

19 minutes ago, Artie said:

(what can I say, I’m married, trained well LOL)

My wife's still trying to train me after 35 years of marriage.  

We're required to use two 8' ground rods 6-8' apart. I know what you mean about driving those ground rods, it never seems to fail that you'll find a big rock or something about half way down.  

13 minutes ago, Larry Buskirk said:

My wife's still trying to train me after 35 years of marriage.  

We're required to use two 8' ground rods 6-8' apart. I know what you mean about driving those ground rods, it never seems to fail that you'll find a big rock or something about half way down.  

I’m not saying I’ve ever cut one, BUT..... make sure you peen the head of the rod good, iff’n you wuz to cut one LOLOLOL.

I wondered if anyone else had done that. Not that I ever did.

1 hour ago, Artie said:

I’m not saying I’ve ever cut one, BUT..... make sure you peen the head of the rod good, iff’n you wuz to cut one LOLOLOL.

All four of mine are full length, I can't remember how many tries it took to finally get them that way. 

Larry, they don’t have to go straight in, you can put them in on a pretty steep angle. Having said that, still a job for the helper LOL.

@Artie

My helper.

You KNOW what you’re doing!

I do not know code but I have never seen more than one ground rod in MS on homes we have had. But now I will have to look.

Not all states go by NEC. Many make changes to it. Massachusetts does, then passes it as law. It becomes Mass state code. 1 ground rod is sufficient, but you must prove 50 ohms or less resistance (I believe it’s 50, wouldn’t swear to that number), if you just install 2 rods, no resistance metering required. I installed two on a service change I did for my Grandfather’s neighbor on Plum Island (relative of Alan Shepard the astronaut). I threw the rod into the sand, it went more than halfway down, I hit it with a 3 pound sledge, and it disappeared into the sand. I had to dig down to find the end and pull it back up. I put two rods in the sand, and when it’s dry out, I wouldn’t trust that ground, but it met code.