Cold Sequence Metering & Service Disconnect

[cdcengineer]

The local utility requires cold sequencing for single phase commercial metering installations.

The local electrical inspector is convinced that if you have for example a 200 Amp, 1-Phase, self-contained metered service than you must have a separate service disconnect.

Our application has the "service equipment" rated 200 Amp disconnect located outside the building directly adjacent to the utility meter. I see nothing in the NEC that says that the cold sequence disconnect cannot be service disconnect. The installer would be required to provide GEC at the disconnect and bond the neutral to ground at this point. From there inward we would need a EGC which would ground the meter housing. At the main panel there would be no bond.

Some utilities will not allow the customer to operate the cold sequence disconnect because they want to ensure that the meter stays hot. beyond that I can't argue against it.

Anyone want to chime in?

Thx - DC

 

[George Stolz]

If the utility wants a cold sequence on that kind of installation, I thought they generally have a utility disconnect -> meter -> service disconnect setup.

 

[cdcengineer]

Are you referring to some sort of all-in-one type of equipment? I've seen disconnect/meter but not a disc/meter/disc.

 

[George Stolz]

No, a separate disconnect ahead of your typical metermain.

 

[George Stolz]

The local utility requires cold sequencing for single phase commercial metering installations.

Before you get too carried away, I'd ask to see the requirement. Chances are, there is an exception to that rule that you can take advantage of anyway.

 

[cdcengineer]

The inspector is working with the contractor. But the inspector is adamant that it's a violation of NEC. He was worried about bonding the service disconnect in more than one place. I never instructed anyone to bond outside of the cold sequence disconnect. Just curious if anyone else has run into anything like this.

 

[George Stolz]

But the inspector is adamant that it's a violation of NEC.

I think you'd have to spell out how it was bonded for us to make that determination.

Essentially, the neutral would be tied to the can in the utility disconnect, no EGC, no GEC, just bonding the can to the neutral. Then proceed as normal in the normal service disconnect.

 

[__dan]

cold sequence

cold sequence

If the disconnect is ahead of the meter, cold sequence, that disconnect is the single point of common connection between EGC, GEC, and system neutral. Everything after that is wired like a subpanel, insulated neutral conductor and insulated neutral terminations, separate EGC. The meter socket can be ordered with an insulating kit for the meter neutral bar.

 

[hillbilly1]

This has always been kinda a grey area, since most meter bases have the neutral solidly grounded to the can, you cannot actually isolate the neutral until it hits the second disconnect.

 

[cdcengineer]

But that second disconnect wouldn't be service disconnect because the neutral would be isolated - correct?

 

[mivey]

If the disconnect is ahead of the meter, cold sequence, that disconnect is the single point of common connection between EGC, GEC, and system neutral. Everything after that is wired like a subpanel, insulated neutral conductor and insulated neutral terminations, separate EGC. The meter socket can be ordered with an insulating kit for the meter neutral bar.

Which our regulated utility can do when ground-fault protection is in play.

B. Bonding Load-Side Metering Equipment
1. General:
...
Where meter equipment is on the load-side of a service disconnect that does not have equipment ground-fault protection and where the meter equipment is adjacent to the service disconnect (within 30 feet), the metal meter enclosure shall be bonded to the grounded (neutral) conductor within the enclosure.
...
Where load-side metering equipment is on the load-side of equipment ground-fault protection or where load-side metering equipment is not adjacent to the service disconnect (not within 30 feet), it is the responsibility of the Customer to coordinate a joint agreement between the AHJ (Authority Having Jurisdiction) and the Company for the proper isolation of the equipment grounding conductor and the service grounded (neutral) conductor within the meter enclosure.

2. Self-Contained Sockets: In all three-phase and single-phase self contained Company meter sockets, the neutral connector is bonded to the metal enclosure by design. A singlephase 200 amp self-contained socket (with bypass handle) is available with a removable bonding strap. A kit is also available from the Company for isolating the neutral conductor from the metal enclosure on four-wire three-phase self-contained 200 amp meter sockets. This will allow these sockets to be bonded by the Customer?s equipment grounding conductor (bond wire) when the socket is on the load-side of equipment ground-fault protection or when the socket is on the load-side of a service disconnect...

 

[steve66]

On cold sequencing metering, won't the POCO lock the breaker in the on position, or prevent access to the breaker by locking the cover?? Don't they do this to prevent someone from tapping in in front of the meter and stealing power??

If so, it seems like you would have to provide another disconnect that the owner can turn off.

 

[defears]

Here in NJ the poco wants a non-fused disco ahead of the meter on commercial services with more than one customer on the same transformer. It's in their book. To the NEC it doesn't exist. Bond the Neutral to the can in the disco and meter and then the NEC starts. The poco will lock that disco like the meter and you'll never see the inside again.

 

[iwire]

To the NEC it doesn't exist.

If it did not exist to the NEC it would not be allowed.

230.82 Equipment Connected to the Supply Side of Service
Disconnect. Only the following equipment shall be
permitted to be connected to the supply side of the service
disconnecting means:

(3) Meter disconnect switches nominally rated not in excess
of 600 volts that have a short-circuit current rating
equal to or greater than the available short-circuit current,
provided all metal housings and service enclosures
are grounded in accordance with Part VII and
bonded in accordance with Part V of Article 250. A
meter disconnect switch shall be capable of interrupting
the load served.

Welcome to the forum.

 

[jim dungar]

On cold sequencing metering, won't the POCO lock the breaker in the on position, or prevent access to the breaker by locking the cover?? Don't they do this to prevent someone from tapping in in front of the meter and stealing power??

Not always. Sometimes they use a simple wire seal. Sometimes they don't do anything.

 

[defears]

Let me rephrase. It doesn't exist as far as the main bonding jumper is concerned. It's poco owned after the inspection and we all know they don't like equipment grounds in their enclosures. :roll:

Btw. Thanks for the welcome.

 

[cdcengineer]

Let me rephrase. It doesn't exist as far as the main bonding jumper is concerned. It's poco owned after the inspection and we all know they don't like equipment grounds in their enclosures. :roll:

Btw. Thanks for the welcome.

But in this example there would be an EGC in the meter can..

 

[cdcengineer]

On cold sequencing metering, won't the POCO lock the breaker in the on position, or prevent access to the breaker by locking the cover?? Don't they do this to prevent someone from tapping in in front of the meter and stealing power??

If so, it seems like you would have to provide another disconnect that the owner can turn off.

Steve - in many cases this is correct. But would the POCO disc be considered service disconnect? If so, than a MCB panel would allow the customer to disconnect w/o the use of the POCO disconnect and the bond would be in POCO's disconnect. Otherwise the cold sequence disconnect would not have the neutral boned, that would take place in the MCB panel.

 

[defears]

The disco I'm talking about is just a switch. No over current protection at all. No fuses or breaker, just a switch to break the load before the meter. The poco requires it, not the NEC. We get paid to install it but the poco requires it. The MAIN SERVICE starts after the meter. So it goes like this NON-FUSED disco >>> Meter >>> Your Main service disco with main bonding jumper like normal. Treat the first disco like it is the meter. Check with your poco first. It should be in writing somewhere.