OT: Electrical Grounding

There are a lot of folks on this forum that are real up to date with electrical codes and I have a grounding question that I researched a great deal and still I am confused. I understand that the service neutral and ground (earth) should only be connected in one place and that is the service dissconnect, and in my case the service disconnect is the main breaker box where the main 200 amp disconnect lives. But in the meter can (Millbanks) the neutral from the power company and the neutral going to the Main breaker box are on a buss bar that is bolted to the meter can directly, there is no isolation device that I can see by looking. In addition to the Neutral conductors on the nuetral buss bar there is also the ground conductor from earth and the ground conductor that goes to the main breaker box (service disconnect). In my mind this also is a connection between neutral and ground and should be removed and the ground passed though the meter can, but this leaves the meter can without a earth ground. I am certain that from the main breaker box to the rest of the house all neutrals and grounds are seperate as they are supposed to be, but I'm not sure about the meter can. If someone could offer some insight that would be great. Thanks in advance and I included a picture.


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If I understand this correctly in this case. The neutral bond to earth at the meter base is sufficient. The neutral and grounding systems should be isolated at all other panels,services. To eliminate the neutral from raising the ground system above true earth potential.
Ideally all breaker panels should have all the grounds interconnected from building to building.

Thank you for the reply and for your help.

So you would recomend removing the neutral to ground jumper in the main breaker box and using the neutral to ground (earth) connection in the meter can? Unfortunately for me the main breaker box was wired by a shadetree electrican (me and I can't remember your term but it applies) and there are instances of the grounding conductors being landed on the neutral buss bar, it would be some work to seperate the ground and neutral in the Main Breaker Box but it could be done-should it be done? I certainly want a safe application that would also meet code although it is doubtful that it would ever be checked.

Regular guy, Its been yearsssssss since I was a secondary power distribution engineer so Im a bit rusty on the latest code, that being said however, here are my thoughts.

I was taught and designed PER THE PRINCIPLE OF "SINGLE POINT GROUNDING". One problem is different jurisdictions and utilities may do things differently SO CONSULT WITH YOUR LOCAL AUTHORITY AS TO HOW THEY DO THINGS (i.e. do they bond Neutral to earth in the meter base or main panel???) AND DO AS THEY SAY NONE OF US HERE LOL

Sooooooo if the local authority bonds the Neutral to mother earth (via a No 4 copper grounding electrode conductor to a grounding electrode such as driven rod or rods and/or metal pipes etc) IN THE METER BASE, then I would carry 4 wires to the Main panel (2 Hots, Neutral, Equipment ground) AND ISOLATE/SEPERATE the Neutral and Equipment ground buss bars in the Main panel. Of course the grounding screw would bond the panels metallic frame to the equipment ground buss.

HOWEVER if your local authority DOES NOT bond Neutral to earth in the meter base, then Id only carry 3 wires from base to panel (2 hots and Neutral) (the No 4 copper grounding electrode conductor can still carry through to get to the main panel of course, just not tied to Neutral in the base) and inside I would bond the Neutral Buss and Equipment Ground busses together and the No 4 copper grounding electrode conductor would bond to the Neutral.

BUTTTTTTTTTTTTTTTTT if your local authority says bond Neutral to earth (via that No 4 copper grounding electrode conductor) in the meter base AND bond Neutral buss to Equipment ground buss in the panel THEN I GUESS YOURE BOUND BY WHAT THEY TELL YOU so go by them NOT BY ANYONE HERE. That dont jive with my idea of single point grounding of the Neutral (like at base or panel but NOT both) but again Im rusty on the code not having designed for yearsssssssssssss

NOTE some panels have 2 seperate and isolated Neutral Buss and Equipment Ground Busses AND USE A big bar to bond them together when they are to be used as a SERVICE ENTRANCE. If they are used as a downstream sub panel, however, the tie bar is NOT used so they remain isolated.. Some panels (suitable for main service entrance ) only have one big common buss used for BOTH Neutrals and Grounds so they couldnt be used as a sub.

Hopefully other gents such as electricians and design engineers etc more code recent can add to this if I forgot anything or Im incorrect BUT I STILL FAVOR ONLY SINGLE POINT GROUNDING OF NEUTRAL TO THE GROUNDING ELECTRODE CONDUCTOR

Thats my story n Ima stickin to it till proven otherwise lol

Best wishes n God Bless Im headed to a cruise but will check back with yall late Sunday

Ol John T

Your main disconnect should be very close to the meter. I'm not sure of the maximum distance, but normally they're just on opposite sides of a wall. As long as that's the case, you have nothing to worry about and it doesn't matter that there's a redundant connection between the ground and neutral. You only run into problems when there's a connection between the two that's some distance downstream of the disconnect.

Mark, best I recall its like 10 feet maximum but as you say the base is often on the outside wall just opposite from panel so the distance is less then a foot...

John T

As previously stated. Two sets of neutral to ground bonds a few feet apart in the meterbase/main switch or main distribution panel. Are close enough not to cause problems.
Problems arise when the neutral is carrying current and has normal voltage drop all conductors suffer.When somebody goes and bonds it somewhere to ground and makes a path.For neutral current to now also flow on the ground system.
Imagine now when some jackleg electrician plugs in a standby generator into a 240V welding receptacle and tries to push neutral current through the grounding system.
The only path for neutral current can end up being from the building ground rods. Through earth and to the ground rods at the service transformer.
Because the grounding system and earth are not perfect conductors. The grounded system is going to be "live" to some degree. Somewhere between 1 and 120V depending.

In this area that would be WRONG. What you have then is a parallel conductors(neutral and ground to the panel)since they are hooked to the same place at both ends. As it is illegal to parallel any wire smaller than 1/0 or to parallel wires of two different sizes. The earth ground at the meter may be the power companies idea but is not legal according to code. Easiest way to fix this would be to shut off power, pull the grounds off of the neutral bar in the meter box, and permanently connect them with an irreversible splice(crimp, solder, etc) as a gound cannot be legally spliced otherwise. The lack of an earth ground at the meter isa in no way a problem. Sorry for being so long winded.

The neutral is never ever to be switched with but one exception anywhere. When using a standby generator with the neutral bonded to chassis inside the generator.

The utility will also try and get away with a bond between the primary neutral running down the road.To the neutral on the secondary side neutral of the service transformer. This can bring problems with neutrals being 5-10 or more Volts above true earth.
That aside there has to be a single full time connection to earth from the secondary side neutral of the service transformer.Which is in reality usually being two or three close bonds together.
A bond up on the transformer pole, a bond at the meterbase and sometimes a bond at the distribution panel.The bond at the distribution panel should be opened.
If there is a long cable run between the meter base and the transformer pole. Lots of neutral current on the utility side of the trans former and dry earth. The grounds at the meter base can easily be 5-10+V above true earth potential.

I would make no changes!
the power company does not play by the same rules as the rest of us.
local and state code enforcers say what happens in the meter can will be per the power company everything else is under their juristiction for code enforcement
Ron

(quoted from post at 18:50:42 02/13/10) I would make no changes!
the power company does not play by the same rules as the rest of us.
local and state code enforcers say what happens in the meter can will be per the power company everything else is under their juristiction for code enforcement
Ron

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Exactly! What everyone's opinions, experiences, 'ought to be's don't count for jack, when the power company refuses to connect.
TXU for example:
CUSTOMER'S GROUNDING ELECTRODE CONDUCTOR SHALL ORIGINATE IN THE SERVICE ENTRANCE EQUIPMENT AND EXTEND TO AN APPROVED GROUND ELECTRODE. THE GROUND ELECTRODE CONDUCTOR SHALL [u:94d5655055]NOT[/u:94d5655055] TERMINATE WITHIN THE METER SOCKET. COMPANY RESERVES THE RIGHT TO REFUSE INSTALLATION OF SERVICE CONTINGENT UPON OBSERVING AN UNSAFE CUSTOMER CONNECTION.

Clearly TXU expects their meter base enclosure to be connected to earth only by the neutral connection from the service entrance equipment.

And you can be sure the same will not apply where ever you may live!
As was said long before so many said so many words, in so many posts, ........check local codes and local power company, period!

Darn, just when a person thinks he has it figured out there is another gray or is it grey area. )

(quoted from post at 21:27:08 02/13/10) Darn, just when a person thinks he has it figured out there is another gray or is it grey area. )

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ell, just to further muddy (gray) the waters, I have another place in area served by FEC (Farmers Electric Co-Op) & they insist on the ground wire from the 8 foot rod be connected to their meter base. Ya just gotta see what your locals want! No "one size fits all" here.

Sounds like everyone has it figured out. NEC doesn't apply to power companies. The utilities all do it different. Around here they bond the meter box (which belongs to the power company even though you pay for it) and your service entrance to the same ground rod(s) if they are within 10' of each other.

Problem is all the different types of power distribution systems in the country and how they ground them. John or Buick (assuming they have and want to take the time to hold class) can teach us a few things about corner grounded deltas, wyes, phases, and all that other power company rigamarole which also affects the type and taps on transformers. I personally haven't studied it much except to know there are different ones. The last time I did look at it, one of my eyes became a delta and the other became a wye, they crossed, and short circuited my brain.

(quoted from post at 00:12:39 02/14/10) Sounds like everyone has it figured out. NEC doesn't apply to power companies. The utilities all do it different. Around here they bond the meter box (which belongs to the power company even though you pay for it) and your service entrance to the same ground rod(s) if they are within 10' of each other.

Problem is all the different types of power distribution systems in the country and how they ground them. John or Buick (assuming they have and want to take the time to hold class) can teach us a few things about corner grounded deltas, wyes, phases, and all that other power company rigamarole which also affects the type and taps on transformers. I personally haven't studied it much except to know there are different ones. The last time I did look at it, one of my eyes became a delta and the other became a wye, they crossed, and short circuited my brain.

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Yes, & I bet John T (the lawyer I believe) can 'splain why the power company (TXU) doesn't want that ground wire to terminate in 'their' sealed meter base, too. :wink:

Thank you everyone for the great suggestions and insight all are appreciated, I guess now I simply need make the corrections and I believe that pulling the two ground wires off of the neutral buss and connecting them together will get me as close as I can come to meeting the code, I realize that because the grounding conductor is broken that does not meet code, but I might have to live with that. Thanks again.