Terminating GEC in Two-Unit Dwelling (Drawing)

[DSamson]

I need some help on how to terminate the GEC in a two unit dwelling.

Please see my crude drawing attached.

View attachment 763

Typically, I have seen this done this way:

1) GEC hits rods and water pipes (one continuous conductor),
2) enters the meter socket (no bonding bushing, this conductor is not in a raceway)
3) GEC hits a bonding bushing on each of three nipples,
4) then ends at the neutral bus in the meter socket.

One inspector is saying this is o.k., the other inspector is saying that the GEC needs to continue through to the CB panels because those include the service disconnects.

If this is true, that the GEC needs to continue to the CB panels, how do I accomplish this? Do I add a small bus in the meter socket and bond it to the enclosure and then therminate the GEC there and then run additional condutors from the bus in the meter socket to the neutral bus in each CB panel?

OR, do I make an enclosure just below the meter socket, terminate the GEC to a bus there, and then run conductors to each CB panel neutral bus?

I don't own large crimping equipment and I haven't been able to find a place to rent it locally. I believe that the ideal solution would be to tap the GEC below the meter socket with suitable crimp connectors and then run a tap to each CB panel (skipping the meter socket altogether).

Thanks for your help.

 

[iwire]

Here is a NEC Handbook example.

The taps can be made with split bolts.

Check out 250.64(D)

This is from the 2002, you should verify it from the 2005.

250.64(D) Grounding Electrode Conductor Taps. Where a service consists of more than a single enclosure as permitted in 230.40, Exception No. 2, it shall be permitted to connect taps to the grounding electrode conductor. Each such tap conductor shall extend to the inside of each such enclosure. The grounding electrode conductor shall be sized in accordance with 250.66, but the tap conductors shall be permitted to be sized in accordance with the grounding electrode conductors specified in 250.66 for the largest conductor serving the respective enclosures. The tap conductors shall be connected to the grounding electrode conductor in such a manner that the grounding electrode conductor remains without a splice.

It is important to realize that only the GEC has to be continuous, not the bonding jumpers between electrodes.

Check out this other Handbook example.

There is nothing wrong with using one continuous conductor from electrode to electrode but it can be a real pain and is not required by the NEC.

 

[iwire]

By the way, a 4 AWG GEC seems a bit small for two services running to the water line....but the section running to the rods ever has to be larger than 6 AWG CU

Did you base the GEC size on the total of the service entrance conductors supplying the two gang socket?

 

[infinity]

As Bob said your GEC is not required to be continuous and could end at the first rod in your schematic. All of the other connections would be bonding jumpers and are not required to be crimped. He has posted some excellent graphics. For the record around here the POCO does not permit GEC connections within their metering equipment.

 

[DSamson]

Sizing GEC - Replies to above

Sizing GEC - Replies to above

The conductors supplying the two-gang socket are 2 AWG copper (small units, no electric heat, no electric cooking). So According to 250.66, 8 AWG is fine for the GEC. The only reason I'm using 4 AWG is because the inspectors have never seen a location that's not "subject to physical damage."

iwire - I have one question about the graphic you included from the handbook. The graphic seems to show disconnects before the meter. Our POCO won't allow disconnects before the meter in most situtations. Would you still take the GEC to the disconnect rather than the meter socket?

Can you help me with the authoriy for using a split bolt for the taps? I only see 250.30(A)(3) for SDS, requiring a permanent connection for taps.

infinity / iwire - I appreciate that the bonding jumpers do not need to be continuous. For some reason, that's what the inspector wants to see, one continuous conductor.

Thanks so much for your help.

 

[infinity]

infinity / iwire - I appreciate that the bonding jumpers do not need to be continuous. For some reason, that's what the inspector wants to see, one continuous conductor.

Thanks so much for your help.

He wants to see it that way because he doesn't really understand the requirement. Personally I would print out Bob's graphic and hand it to him because I would not be using a continuous conductor.