Having trouble understanding installation of bonding for service (2011 nec)

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green2012

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highland park, il
I have a 200 amp overhead service installation. I have a 200 amp meter with disconnect (breakers) on the exterior and a 200 amp main disconnect inside. Im required to install grounding bushings in several locations. I'm gonna walk through the installation starting at the top and say how the grounding bushings are utilized. The 2" rigid comes into the meter via a hub (no G-bushing required), a 2" rigid leaves the meter entering the home and landing in the panel ( G-bushing on both sides ), a 3/4" leaves the panel and goes to cold water (G-bushing on panel side/ ground kit at cold water), there is also a 3/4 rigid exiting the meter to ground rod.( Gbushing)


A #6 runs from the ground rod- gets a portion stripped and looped through the grounding bushing and lands on the ground bar inside the meter. From the ground bar inside the meter a #4 runs up and (1) loops through the ground bushing, leaves the meter, and (2) gets looped through the ground bushing on the panel side. It runs through the panel and (3) looped through the ground bushing on the 3/4 before leaving to land on the cold water at the other side.

My question is about the loop labelled (2). Im wondering if that grounding bushing should bond to the panel rather then the grounding electrode wire. The meter housing is effectively grounded by its ground bar where the ground rod and cold water electodes start, and the point of all the other grounding bushings are to ensure that the pipes are grounded effectively. The panel doesnt "look" effectively grounded. Thoughts?
 
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hillbilly1

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North Georgia mountains
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don_resqcapt19 said:
While the NEC only requires one, some utilities require bonding at both ends.
Click to expand...

Here, Georgia Power prohibits them in their equipment.

fmtjfw said:
You need to bond the grounding electrode conductor at both ends of the rigid conduit containing it.
Click to expand...

Yes, if the GEC in this case is run in with service conductors, but here, it is also prohibited by Georgia Power.
 
augie47

augie47

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State Electrical Inspector (Retired)
I may be badly mistaken, but I see it differently.
The way I read your original post, it sounds like a meter/disconnect combo in one unit.
If I am mistaken, the other posts make sense to me.
If I am correct, assuming we are talking less than 150 volts to ground, the NEC would not require any bonding bushings on conduits with conductors AFTER the service disconnect other than (a) loosely fitting raceways and (b) grounding electrode conduits. So, IMHO, no grounding bushing are need on your conduit from the outside disconnect to the interior panel.

Bonding would be required on each end of metallic conduits containing grounding electrode conductors.
 
stickboy1375

stickboy1375

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Location
Litchfield, CT
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green2012

Member
Location
highland park, il
Im still not clear on the method of using the grounding bushing. In all situations other then the one inside the load center looping the grounding conductor through the bushing makes sense. The point of the grounding bushing is to make sure the pipe remains grounded. If locknuts come loose or if concentric knockouts were used and they fall out. Because the meter outside has a disconnect, I need to bring my grounding electrodes to it not the panel. In the past (when meters were not required to have a disconect in them) the electrode landed inside the panel and a jumper from the nuetral to the panel housing was made. Since there isnt a jumper inside the panel; what is grounding the panel? Just the pipe?
 
infinity

infinity

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Location
New Jersey
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Journeyman Electrician
green2012 said:
I have a 200 amp overhead service installation. I have a 200 amp meter with disconnect (breakers) on the exterior and a 200 amp main disconnect inside. Im required to install grounding bushings in several locations. I'm gonna walk through the installation starting at the top and say how the grounding bushings are utilized. The 2" rigid comes into the meter via a hub (no G-bushing required), a 2" rigid leaves the meter entering the home and landing in the panel ( G-bushing on both sides ), a 3/4" leaves the panel and goes to cold water (G-bushing on panel side/ ground kit at cold water), there is also a 3/4 rigid exiting the meter to ground rod.( Gbushing)


A #6 runs from the ground rod- gets a portion stripped and looped through the grounding bushing and lands on the ground bar inside the meter. From the ground bar inside the meter a #4 runs up and (1) loops through the ground bushing, leaves the meter, and (2) gets looped through the ground bushing on the panel side. It runs through the panel and (3) looped through the ground bushing on the 3/4 before leaving to land on the cold water at the other side.

My question is about the loop labelled (2). Im wondering if that grounding bushing should bond to the panel rather then the grounding electrode wire. The meter housing is effectively grounded by its ground bar where the ground rod and cold water electodes start, and the point of all the other grounding bushings are to ensure that the pipes are grounded effectively. The panel doesnt "look" effectively grounded. Thoughts?
Click to expand...

The way I read it, the 2" RMC is the only service raceway and is bonded via the hub to the meter enclosure. In this installation, nothing would require a grounding bushing with the exception of a ferrous raceways containing the GEC's.
 
augie47

augie47

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Tennessee
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State Electrical Inspector (Retired)
A bonding method other than standard locknuts is required on the line side of the service disconnect as you don't have an immediate overcurrent protective device to limit current. Your 200 amp outside breaker should limit current sufficiently for you pipe to be an acceptable grounding means. If you wish to add additional bonding means you certainly can.
 
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