100 amp s.p meter socket w/ combination main

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MannyBurgos

Senior Member
Location
Waukegan, IL
Hello all. I need a slight dirrection towards bonding and grounding a 100 amp. eter socket combination main disconnect. Local ahj wants ground rod and gec to water meter. What i plan to do is:
-bond neutral at main disconnect (meter socket),
-run a gec to ground rod from meter socket.
-run my 3- service conductors in pipe 15 feet away to breaker panel
- and since an additional supplemental ground is needed, i plan to run a conductor from ground buss bar to water meter...

Does this sound right according to N.E.C? I don't want to take any short cuts. Another inspector passed one of my jobs like this recently but i'm a little skeprical about his knowledge as well...

Thanks all!
 

david luchini

Moderator
Staff member
Location
Connecticut
Occupation
Engineer
- and since an additional supplemental ground is needed, i plan to run a conductor from ground buss bar to water meter...

Does this sound right according to N.E.C? I don't want to take any short cuts. Another inspector passed one of my jobs like this recently but i'm a little skeprical about his knowledge as well...

Thanks all!

This doesn't sound compliant to me. All of the grounding electrodes should be bonded together, and the GEC connection should be made anyplace from the service drop or lateral to the service disconnecting means.

I think if you bond the water pipe to the ground rod (rather than connect it to the panel ground buss) then it would be compliant.
 

MannyBurgos

Senior Member
Location
Waukegan, IL
This doesn't sound compliant to me. All of the grounding electrodes should be bonded together, and the GEC connection should be made anyplace from the service drop or lateral to the service disconnecting means.

I think if you bond the water pipe to the ground rod (rather than connect it to the panel ground buss) then it would be compliant.

I believe all electrodes will be bonded as the ground buss bar in the breaker box will be effectively grounded with the metal enclosure which is also bonding by emt from breaker box to meter socket. Would that not be correct?
 

david luchini

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Location
Connecticut
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Engineer
I believe all electrodes will be bonded as the ground buss bar in the breaker box will be effectively grounded with the metal enclosure which is also bonding by emt from breaker box to meter socket. Would that not be correct?

I don't think that would meet the requirements of bonding the electrodes together per 250.53(C).
 

david luchini

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Location
Connecticut
Occupation
Engineer
Thank you for leading me to the correct reference. 250..64(c)(2) permits sections of busbars to to form GEC. So in my case, would that be acceptable?

I don't think 250.64(C)(2) applies to your situation. That section describes making splices or connections in the GEC where permitted to be made per 250.30(A)(5) and (A)(6) and 250.68(C).

Your GEC is from the ground rod to the main disconnect. The ground bus in the panel plays no part in that GEC.

You still need to bond your electrodes together per 250.53(C). (Note that 250.53(C) says that the bonding jumper shall be installed in accordance with 250.64(A), (B) and (E). It does not say 250.64(C).)
 

Gaffen99

Senior Member
Location
new jersey
I always installed all GECs to main disconnect, in this case that would be the meter socket. Than run a ground wire with the entrance conductors to the panel, treat it like a sub panel.
 

augie47

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Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Hello all. I need a slight dirrection towards bonding and grounding a 100 amp. eter socket combination main disconnect. Local ahj wants ground rod and gec to water meter. What i plan to do is:
-bond neutral at main disconnect (meter socket), !

no problem
-run a gec to ground rod from meter socket.!

no problem as long as POCO allows
-run my 3- service conductors in pipe 15 feet away to breaker panel
!
As long as you address the equipment ground by a conductor or metallic conduit.
- and since an additional supplemental ground is needed, i plan to run a conductor from ground buss bar to water meter...!

The answer, to me, is in 250.24:
The grounding electrode connection shall be made at any accessible point from the load end of the service drop or lateral to and including the terminal or bus to which the grounded service conductor is connected at the service disconnecting means.
 

MannyBurgos

Senior Member
Location
Waukegan, IL
no problem


no problem as long as POCO allows

As long as you address the equipment ground by a conductor or metallic conduit.


The answer, to me, is in 250.24:
The grounding electrode connection shall be made at any accessible point from the load end of the service drop or lateral to and including the terminal or bus to which the grounded service conductor is connected at the service disconnecting means.

So in my case, my GEC connection will be made at the meter socket enclosure which has approval from POCO. This connection will be from neutral lug to ground rod. My supplemental grounding electrode (which is a requirement per amendments from my local AHJ regardless of 25 ohms or not) will be made from ground busbar in what will now be a subpanel (isolation of neutral and ground) to the water meter street side. SEC are run in R.M.C from meter socket (main) to subpanel. I'm trying to catch the wording on 250.24 terminal or bus to which the grounded service conductor is connected at the service disconnecting means and am not able to fully follow... Does this mean that i have to run my supplemental GEC from water meter directly to main disconnect which is where the primary GEC connection is made?
 

MannyBurgos

Senior Member
Location
Waukegan, IL
I don't think 250.64(C)(2) applies to your situation. That section describes making splices or connections in the GEC where permitted to be made per 250.30(A)(5) and (A)(6) and 250.68(C).

Your GEC is from the ground rod to the main disconnect. The ground bus in the panel plays no part in that GEC.

You still need to bond your electrodes together per 250.53(C). (Note that 250.53(C) says that the bonding jumper shall be installed in accordance with 250.64(A), (B) and (E). It does not say 250.64(C).)

Good catch David! That passed me up. What situations does 250.64(c) apply to?
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
You can not connect any required grounding electrode conductor to a panel beyond the service panel. (There are exceptions)
The ground rod, water pipe, ufer, steel ,etc would need to connect to the grounded conductor in or before your service disconnect (1st means of disconnect) or to another appropriately sized grounding electrode conductor or another grounding electrode.
 

MannyBurgos

Senior Member
Location
Waukegan, IL
You can not connect any required grounding electrode conductor to a panel beyond the service panel. (There are exceptions)
The ground rod, water pipe, ufer, steel ,etc would need to connect to the grounded conductor in or before your service disconnect (1st means of disconnect) or to another appropriately sized grounding electrode conductor or another grounding electrode.

Thanks Augie. I kind of understand now. I was under the impression that the metallic raceway from sub panel to service panel would serve as the GEC. Therefore, I thought that terminating my supplemental GEC at sub panel ground bus which is isolated from neutral and bonded to enclosure would take care of the GEC connections via the heavy wall conduit between panels... Maybe not....
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Keep in mind, with grounding electrode conductors, if they are needed, they might well be conducting extremely high currents from surges or lightning.
The path to earth needs to be as clean as possible. If the current had to travel thru your conduit it would also need to travel thru all locknut terminations, etc,. There could well be a weak link in that path.
 

MannyBurgos

Senior Member
Location
Waukegan, IL
Keep in mind, with grounding electrode conductors, if they are needed, they might well be conducting extremely high currents from surges or lightning.
The path to earth needs to be as clean as possible. If the current had to travel thru your conduit it would also need to travel thru all locknut terminations, etc,. There could well be a weak link in that path.

Your right. And that is why we are required to use bonding bushings where required (cocentric, blah, blah, blah, etc.) Thanks for your help. Will be running 4 conductors instead of 3 from main disconnect to sub panel HOWEVER, the 3rd conductor will be running straight through panel (with no splices), and connecting to water meter :thumbsup: (don't worry, there is adequate space in sub panel to use as pull box) :D
 

GoldDigger

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Location
Placerville, CA, USA
Occupation
Retired PV System Designer
I still see lack if clarity as to EGC, bonding jumper, and GEC.
With the requirement for a continuous GEC, allowing irreversible splices, I do not really see raceway or panel being part if a GEC.
Some of what has been described relates to EGC and some to assorted bonding jumpers. I suppose that you could use raceway or sheet metal as part of a bonding jumper or bus to bus connection.
 

MannyBurgos

Senior Member
Location
Waukegan, IL
I still see lack if clarity as to EGC, bonding jumper, and GEC.
With the requirement for a continuous GEC, allowing irreversible splices, I do not really see raceway or panel being part if a GEC.
Some of what has been described relates to EGC and some to assorted bonding jumpers. I suppose that you could use raceway or sheet metal as part of a bonding jumper or bus to bus connection.

Can you clarify a little Digger? Raceway is bonding main and sub panel with bonding jumper located at main disconnect. neutral and ground are terminated on same busbar at main disconnect with an isolation of neutral and ground at sub panel. Chime in please.
 

GoldDigger

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Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
Can you clarify a little Digger? Raceway is bonding main and sub panel with bonding jumper located at main disconnect. neutral and ground are terminated on same busbar at main disconnect with an isolation of neutral and ground at sub panel. Chime in please.
If I felt a lot of clarity, I would have been clearer to start with.... :)
AFAIK the code does not require all GECs to terminate at the same place. If it did, then you would have to bring any additional electrode to the same point via a continuous conductor.
But there seems to be a majority opinion (not quite a consensus) that everything beyond the first GEC is just a bond and not subject to the continuity rule.
Let's see what others have to add.
 

MannyBurgos

Senior Member
Location
Waukegan, IL
at first i thought 250.64 (c)(2) would allow me to install as i originally wanted however, 250.24(a)(5) says no load side grounding connections. 250.50 provides requirement for bonding all GEC to form GES which would be my ground rod and water pipe. Am i on track or excep...
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Your right. And that is why we are required to use bonding bushings where required (cocentric, blah, blah, blah, etc.) Thanks for your help. Will be running 4 conductors instead of 3 from main disconnect to sub panel HOWEVER, the 3rd conductor will be running straight through panel (with no splices), and connecting to water meter :thumbsup: (don't worry, there is adequate space in sub panel to use as pull box) :D

Assuming you are saying that your 4th conductor is the Grounding Electrode Conductor to the water pipe, keep in mind, when you route that conductor thru your metal nipple you must bond both ends to the conductor. (250.64)(E)
 

kwired

Electron manager
Location
NE Nebraska
A water pipe electrode is required to have a supplemental electrode, that makes the ground rod in this instance the supplemental elecrode - JMO. OP seems to be calling the water pipe the supplemental electrode. I feel that since all qualifying water piping, building steel, or concrete encased electrodes are required to be used if present, they become "primary" over rods, pipes or other optional made electrodes. Should you have both a water pipe and building steel or CEE you are not required to use any additional electrodes per NEC, some utilities or local AHJ's still sometimes want a rod though, but it is not one of the "automatically" required to be used electrodes by NEC.
 
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