I have a nontypical (for me) service I'm currently working on. It is a multi tenant building with two separate 4000 amp services, service #1 and service #2. Service 1 is your straight forward utility transformer --> ct cabinet --> main breaker --> distribution panels etc. type of service. Service #2 is a little different as where instead of the transformer secondary going straight to a CT cabinet and then into the building the secondary instead goes to a sectional cabinet and then into the building, no metering yet. Once in the building it goes right to a gear lineup that includes a 4000 amp breaker section buss tied to an I-line distribution section which is buss tied to a 1600 amp breaker section which then goes to a CT cabinet inside the building. The 1600 CT cabinet feeds a service rated ATS which then runs off and serves the loads designated for it. The I-line distribution section has (2) 800 amp breakers feeding (2) 800 amp meter packs for multiple commercial tenants. The gear lineup for service 2 is wired exactly as it would be if it were downstream from the utility meter, i.e. neutral/ground bond in the main section. My question is whether or not any of this wiring is under the purview of the NEC before it hits a utility's meter? In actuality "service #2" will feed multiple services and each service will be treated and wired accordingly but I'm just not used to seeing so much equipment before any actual metering. Hope this makes sense, thanks for any input.
Large Service Wiring Methods Before Meter
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kwired
Electron manager
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- NE Nebraska
Whether or not NEC applies should be dependent on where the "service point" which is in art 100 definitions is located and this is exactly a situation that was in consideration when they decided to add this term and definition not too many code cycles ago.
If the utility owns and/or maintains the equipment ahead of the metering equipment then it likely is on the supply side of the service point.
Large meter centers often are on the load side of the service point though, the POCO only installs a meter in each position and puts a lock on the meter compartment to prevent meter tampering, but the gear itself is customer owned and maintained and on the load side of the service point.
If the utility owns and/or maintains the equipment ahead of the metering equipment then it likely is on the supply side of the service point.
Large meter centers often are on the load side of the service point though, the POCO only installs a meter in each position and puts a lock on the meter compartment to prevent meter tampering, but the gear itself is customer owned and maintained and on the load side of the service point.
Thanks for that clarification, I was not aware of a "service point", my guess is the utility has defined the termination cabinet outside as the service point, it sits adjacent to the CT cabinet for the other service
hillbilly1
Senior Member
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- Owner/electrical contractor
From the sounds of it, the ct cabinet is where the poco ends, and the landlord is metering after that. Otherwise, the customer would be charged for the power used when source 2 is used, and if it isn't owned by the utility, then they are going to make out like a bandit on selling power they didn't produce.
The CT meter is for the building owners equipment, 2 floors of this building are for multiple tenants, their metering will be done separately via gangable meter packs
kwired
Electron manager
- Location
- NE Nebraska
Is there metering of conductors in said CT cabinet and that is the utility metering and the further downstream meter pack is for non utility company monitoring reasons? As mentioned as described the meters in the meter pack would be metering any on site produced power as well as utility provided power.
I see you posted the answer as I was composing this reply.
kwired
Electron manager
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- NE Nebraska
Many but not all installs the service point would likely be at/near/within that POCO CT metering cabinet. The cabinet itself may be customer or utility owned and maintained, it varies some but that is typically the transition point where POCO ends and NEC begins.
hillbilly1
Senior Member
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- North Georgia mountains
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- Owner/electrical contractor
Ok, then the 4000 has a 1600 amp and two 800 amp breakers in it? The way it was worded, it appeared the two 800's feed from the 1600. Gotcha now!
A CT cabinet is the logical location for a service point but I don’t think it would be possible for this set up considering there are other utility metering enclosures besides the CT cabinet. The only point in this service that makes sense as a service point would be the termination cabinet outside. From there it goes to a 4000 amp main and other over current sections for multiple tenant metering, those sections of gear are not owned and maintained by the utility.
Also, now knowing all this, is it common to have multiple neutral/ground bonds after the service point? As of now I have it in the 4000 amp main breaker section, the 1600 amp service rated transfer switch, and I’m guessing each meter pack enclosure.
kwired
Electron manager
- Location
- NE Nebraska
The separation point is the service disconnecting means. Before and up to service disconnecting means you bond things to the grounded conductor. After the service disconnecting means you only bond things to the equipment grounding condutcor
Right, I realize this. My question is how do you approach it when there are multiple services in the same building being fed from a single utility transformer. I’ve got multiple standing gear sections with multiple over current devices feeding multiple service metering equipment and multiple service disconnecting means. Just having a gelato time getting my head around it, thanks
I’d say my most pressing issue is how to handle the ground to neutral bond in this particular setup: an unmetered 1600 amp breaker feeds a 1600 amp CT cabinet where the utility begins it’s metering. From the CT cabinet the load side goes back to a 1600 amp service rated transfer switch with another 1600 amp breaker. The first 1600 breaker is in a gear lineup that one would traditionally consider the service i.e. 4000 amp “main” breaker and our neutral/ground bond, however, all of this gear is unmetered and simply acting as a distribution point that feeds the multiple services in the building. Considering we have our neutral/ground bond in the distribution gear before the metering can we really do it again after the utility metering begins and in the service disconnecting means?
kwired
Electron manager
- Location
- NE Nebraska
First the general rules is that multiple service disconnecting means from the same source is considered to be one service, those service disconnecting means usually need to be grouped in one location and usually you are limited to six service disconnecting means. There are situations that can allow more than six or allow for not grouping them in one location.
You may have multiple gear with multiple overcurrent devices, but you are still limited to six or less "mains" (service disconnecting means) as the general rule. Do you have six or less "mains" that would kill all power to the associated "service"?
If you have different voltage, number of phases, frequency, etc. or even need more capacity than a utility normally will provide through a single service (though you said this all comes from a single source) then you have conditions that NEC allows multiple services. But you are still limited to six disconnects grouped in a single location for each permitted service.
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