Metering a service

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A strip mall with a 2000 amp, 120/208 volt, 3 phase exterior distribution panel contains a main circuit breaker as the service disconnect. Circuit Breakers will be added to this panel to feed power to the individual units as they are leased. Thirty feet away on both sides of this Panel are huge Gutters designed to feed the individual units of the mall. Six 4" PVC conduits run to each gutter from the service panel, all of which is for future use. At this point there is no metering of the service. Question: Does the NEC stipulate a maximum distance between the meter and the switch feeding it? Question: Since the bonding of the neutral is done at the panel, will the meters need to have Isolated neutrals in each?
 
Answer #1: Location of the meters is usually determined by the power company. Meters are largely ignored by the NEC.

Question: Since the bonding of the neutral is done at the panel, will the meters need to have Isolated neutrals in each?
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No, the neutral passing through the metercan may be used to bond the housing of the metercan. See 250.92(B)(1).

If the question has arisen because the meters are after the main disconnect (often referred to as "cold-sequencing"), then see 250.142(B), exception 2. In this case, the meter would need to be "adjacent" to the service disconnecting means.

"Adjacent" would be an interpretation call on the AHJ's part, IMO.

However, if the metering is cold-sequenced, there's no reason I can think of that you can't remove the bonding strap in the metercan, that connects the neutral to the can from the factory. Then connect the EGC to the metercan as usual.

I'm assuming there's a bank of meters going in, for each tenant of the mall?
 
No bank of meters going in. The gutters were installed to allow more flexibility in the size of electrical service going to each unit.
 
Above the Gutters which are located thirty feet away from the Service switch. The meter cans will probably be "Durham" brand. They are made where the neutral lugs are directly bolted to the can. There is no jumper to remove in order to Isolate it.
 
Above the gutters. When the units are leased the needs of the tenent will dictate the size of the service. The gutters are thirty feet away from the service disconnect. Also to be noted, the gutters are 12" x 12" x 25' long.
 
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I think the biggest imposition to you proceeding as described will be the power company - that's a lot of territory for them to seal off to prevent tampering (stealing power), IMO.

If they do happen to go for it, then I'd recommend looking into metercans that can have the neutral-can bond removed, such as Milbank.

I've only seen the exception I referenced earlier used for modular services, where the meter modules are bolted to the main disconnect, and the Equipment Grounding (Bonding) System begins in each module.

With the PVC conduits running from the MDP to the gutters and the meters, then you will not create parallel neutral paths through the raceway, but if you were to install EGCs starting at the MDP (as you should), then the metercans would need to be bonded to the EGC.

If you connected the neutrals and EGCs at the MDP, and then again at the meters, then you would create parallel paths between the meters and MDP. This would violate 250.6, among other sections.
 
250.142 Exception 2 allows the bonded neutrals at the meters.

Using Milbank meter sockets is no guarantee that the neutral can be isolated.

Milbank makes the sockets to meet local power company requirements.

In this area I have never seen a meter socket that you could isolate the neutral.
 
iwire said:
250.142 Exception 2 allows the bonded neutrals at the meters.

Using Milbank meter sockets is no guarantee that the neutral can be isolated.

Milbank makes the sockets to meet local power company requirements.

In this area I have never seen a meter socket that you could isolate the neutral.
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I can't think of a meter that has the neutral isolated either.
 
In my area the utility companies require heavy duty lever bypass on commercial metering.

One utility company requires a isolated neutral on the load side of a service disconnect as a written spec.

For example an approved 200 amp approved milbank meter U3402 can accept a K1047 feild installed isolated neutral kit.

But then again it all depends on the utility company. It is nice when you can go online and get the specs right away.

On another note:

I can't believe that such a large service would have no utility company input from the start. If their specs are not followed they can be really tough to deal with. I would not want to be in that position.

Joe Villani
 
To be clear, I've only seen Milbank meter sockets with the single-phase, 5th jaw, lever bypass, 200A configuration that had a removable strap to unbond the can from the neutral. I am not sure if they make them with a three-phase configuration.

The only reason I remember it distinctly is because I had to make a return trip to remove the parallel path created when a fellow employee installed a second jumper to bond the can with. It sticks out in my mind because I had an altercation with the inspector, resulting in a rant thread. :D

Anyway, if an unbondable metercan can't be found, should the OP consider running an EGC through the can on it's way to the subpanel, without using the EGC to bond the metercan?
 
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