250.94 Compliance

[bphgravity]

What does section 250.94 require?

Lets say I have a service lateral to a dwelling in PVC conduit. This terminates at meter enclosure back-to-back with the service main and panelboard inside the garage. The GEC originates from the main enclosure and is sleeved in PVC and all other wiring is NM cable. Is there an "accessible means external to enclosures for connecting intersystem bonding and grounding electrode conductors"?

Do those little clamp-on devices attached to the outside of the meter enclosure by the utility companies qualify? Is this really their external and accessible means at the service equipment?

 

[Pierre C Belarge]

This section mentions service equipment... 250.66 says meterpans are not service equipment, yet we see many times that these other systems are connected/bonded to the metepan.

Just a thought!

 

[Cavie]

Bryan, in Ft Myers, they sub a 6" tail of #6 out of the bottom of metercan.

 

[bphgravity]

That is partially why I am asking the question. We have a few contractors working up this way and I see them installing that. I've seen this from two Lee County contractors and figured they were probably enforcing this in Fort Myers and wondered if I was missing something.... :?:

Are you guys using 250.94 to require this installation?

 

[don_resqcapt19]

Pierre,

250.66 says meterpans are not service equipment, yet we see many times that these other systems are connected/bonded to the metepan.

Where does it say that in 250.66. I do agree that the meter can is not "service equipment" per the NEC, but I see no issue making the grounding connection to it. We can use the raceway in and out of the meter and the raceways along with the grounded conductor are bonded to the meter. There is at least one company that makes a clamp specifically for this purpose. Scroll about 1/2 way down on the link.
Don

 

[Pierre C Belarge]

Don

230.66
last sentence.
Individual meter socket enclousures shall not be considered service equipment.

250.94
... shall be provided at the service equipment...

I see the connection at meters all the time.

I just say that by the wording of the NEC this practice would seem to be prohibited.

 

[don_resqcapt19]

Pierre,
Your original post says 250.66, not 230.66. I think that was only added to 230.66 because of the marking rules for service equipment and meters are not listed as service equipment.

I see no electrcial reason that you can't make the communications bonding connection at the meter can. And while they are not "service equipment, 250.92(A)(2) calls them "service enclosures".
Don

 

[eprice]

I see no electrcial reason that you can't make the communications bonding connection at the meter can.

In the scenario described by Brian, where the meter and service are back to back, it wouldn't make much difference, but the NEC does not limit the distance service entrance conductors can run from the meter enclosure, on the outside of the building (or under the slab) before they enter the service disconnect enclosure. Suppose this distance is 100'. Suppose the service entrance conductors are run in PVC and the meter enclosure is bonded to the service grounded conductor. If the communications bonding connection is made at the meter enclosure, wouldn't there be a voltage difference imposed between the communications ground and the building wiring system equipment ground equal to the voltage drop developed in the 100 feet of grounded service entrance conductor?

 

[don_resqcapt19]

eprice,
You are correct in this case that there would be a voltage difference equal to the voltage drop on the grounded conductor.
Don

 

[Cavie]

Ryan, yes 250.94(2). I don't like this because some are not smart enought to loop over the top with the EGC and go thru the lug and straight out the bottom of the can with the six inch tail. Some go thru thew lug first then loop over the top and down thru the bottom of the can and this poses a problem with too much slack. Pull on this tail and you can ingage it with the line side of the meter. I would prefer it to come from the Panel and just stick out thru the house. You will also find them attaching the ufer to the rebar in the block wall and installing a 2 gang mug ring onto the block and installing a blank plate on trimout.