Greenfield in service enterance

[SceneryDriver]

Am EC friend asked me this question last night, and I've been pondering it:

Let's say you have a situation where the service entrance conductors are partially in Greenfield. They come out of the back of the meter pedestal, through 2 ft of Greenfield into a pull box in the basement, and then down to the panel a few feet away in EMT. (The pull box is a splice point to make the house solar-ready via a line-side tap).

Are you required to use bonding bushings on each end of the Greenfield, and pull the #4 ground into the meter pedestal? I say no, because it's ahead of the bonding point in the main panel, and the neutral is bonded to the can in the meter pedestal anyway. What does the green wire do there, and is there even a factory-provided lug to land the green wire? I did suggest he pull the #4 green into the pull box to make everyone feel better about having a good ground if/when the homeowner adds solar in the future.

Thoughts?



SceneryDriver

 

[jaggedben]

If you don't have impaired connections (reducing washers, eccentric or concentric knockouts), then I don't believe bonding bushings are required. See 250.92. Even if you do need bonding bushings, you could put the neutral into them if you wanted, rather than running a green.

And then we get to this part...

I did suggest he pull the #4 green into the pull box to make everyone feel better about having a good ground if/when the homeowner adds solar in the future.

Thoughts?

I think this is a good idea. My reason is that if/when the homeowner adds solar in the future then whoever does it may run into a controversy over whether the disconnect for the supply side connection is a 'service disconnecting means' or not, and thus whether it is supposed to have a neutral-ground bond per 250.24(C) or whether it's not supposed to per 250.6. If the latter then you'll need a green to run to the disconnect and it would be better if it's already there.

I had to look up 'Greenfield' but I gather you're referring to flexibile metallic conduit.

 

[augie47]

I always found the wording of 230.43 interesting when it comes to FMC:
15) Flexible metal conduit (FMC) not over 1.8 m (6 ft)long or liquidtight flexible metal conduit (LFMC) not
over 1.8 m (6 ft) long between a raceway, or between a raceway and service equipment, with a supply-side
bonding jumper routed with the flexible metal conduit(FMC) or the liquidtight flexible metal conduit
(LFMC) according to the provisions of 250.102(A),(B), (C), and (E)

It seems to allow FMC "between a raceway" or "between a raceway and service equipment" so I think there is reasonable question as to it being allowed between the meter and a box,
That point overlooked for a moment, the Section requires a supply side bonding jumper.
There would be no point in using a bonding bushing as you would simply be bonding to a raceway not suitable as a grounding conductor to begin with.

 

[infinity]

Am EC friend asked me this question last night, and I've been pondering it:

Let's say you have a situation where the service entrance conductors are partially in Greenfield. They come out of the back of the meter pedestal, through 2 ft of Greenfield into a pull box in the basement, and then down to the panel a few feet away in EMT. (The pull box is a splice point to make the house solar-ready via a line-side tap).

Are you required to use bonding bushings on each end of the Greenfield, and pull the #4 ground into the meter pedestal? I say no, because it's ahead of the bonding point in the main panel, and the neutral is bonded to the can in the meter pedestal anyway. What does the green wire do there, and is there even a factory-provided lug to land the green wire? I did suggest he pull the #4 green into the pull box to make everyone feel better about having a good ground if/when the homeowner adds solar in the future.

Thoughts?

Since it's on the line side of the service disconnect how is the pull box bonded to the service neutral?

 

[Smart $]

Since it's on the line side of the service disconnect how is the pull box bonded to the service neutral?

I was thinking something similar. Why run a bonding jumper when you already have the grounded conductor in the box?

My working rule of thumb is, if there's a green wire on the line side of the service disconnecting means, someone did something wrong. :angel:

Then there's what Gus/augie47 brought up regarding an SSBJ required. I guess the bonding with grounded conductor is not enough... :huh::blink::huh:

 

[SceneryDriver]

Since it's on the line side of the service disconnect how is the pull box bonded to the service neutral?

I asked the same thing. #4 green hits bonding bushings on either end of the EMT conduit run between main panel's ground bar. Green lands on the ground bar in the panel.

There's apparently also a ground bar field installed in the pull box for possible future solar interconnect.

The EMT run had to be bonded with bonding bushings, since it's in a concentric KO at the panel end.



SceneryDriver

 

[SceneryDriver]

I always found the wording of 230.43 interesting when it comes to FMC:
15) Flexible metal conduit (FMC) not over 1.8 m (6 ft)long or liquidtight flexible metal conduit (LFMC) not
over 1.8 m (6 ft) long between a raceway, or between a raceway and service equipment, with a supply-side
bonding jumper routed with the flexible metal conduit(FMC) or the liquidtight flexible metal conduit
(LFMC) according to the provisions of 250.102(A),(B), (C), and (E)

It seems to allow FMC "between a raceway" or "between a raceway and service equipment" so I think there is reasonable question as to it being allowed between the meter and a box,
That point overlooked for a moment, the Section requires a supply side bonding jumper.
There would be no point in using a bonding bushing as you would simply be bonding to a raceway not suitable as a grounding conductor to begin with.

I guess I agree, but what exactly would it be bonding? The 1/O neutral bonded to the meter can ought to take care of it, yes?



SceneryDriver

 

[infinity]

All metal raceways that contain SEC's require bonding beyond standard locknuts so take a look at 250.92(B). Since your only ensuring that the raceway is properly bonded the method used is only required at one end.

 

[augie47]

I guess I agree, but what exactly would it be bonding? The 1/O neutral bonded to the meter can ought to take care of it, yes?



SceneryDriver

Good question.. this is a case of my just stating what the book states.