480 Service

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Hendrix

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Parallel 250 kcm alum. to a nonfused knife switch (utility required)outside the building, then through ct cabinet to 400a main panel that is about 100' away. Would the knife switch be considered the first means of disconnect and the 400a fused panel act as a sub panel? And would the GEC have to be run to the knife switch?
 
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Okay so I am now thinking you have a service on a building with the feeder run outside and then into the same building? Then I say the knife switch is where the gec goes.
 
I see the knife switch as a utility required cold sequence meter disconnect as permitted by 230.82(3). It is not the service disconnect and cannot be the service disconnect as the service OCPD is not "immediately adjacent thereto" as required by 230.91.

There may be a short circuit current rating issue with the non-fused meter disconnect. As far as I know the maximum short circuit current rating of such a switch is 10,000 amps. The available fault current for this service may exceed 10,000 amps.
 
don_resqcapt19 said:
I see the knife switch as a utility required cold sequence meter disconnect as permitted by 230.82(3). It is not the service disconnect and cannot be the service disconnect as the service OCPD is not "immediately adjacent thereto" as required by 230.91.

There may be a short circuit current rating issue with the non-fused meter disconnect. As far as I know the maximum short circuit current rating of such a switch is 10,000 amps. The available fault current for this service may exceed 10,000 amps.
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Good catch Don.
 
Around here we have one POCO that likes to require a disconnect like that ahead of the meter - usually for 200 amp meter bases @ 480 volt.

It is not uncommon to see for these particular services - on the same structure unfused disconnect - meter - fused disconnect - load equipment.

The fused disconnect is the service disconnect. The unfused disconnect on the supply side of the meter is for the POCO and you can not call it the service disconnect even if you would install a fused disconnect there. They will not allow it to have fuses either because the owner/occupant needs to have access to their service overcurrent device(es), but being on supply side of meter POCO places a lock on it so no one will be able to access it and take unmetered power.
 
kwired said:
Around here we have one POCO that likes to require a disconnect like that ahead of the meter - usually for 200 amp meter bases @ 480 volt.

It is not uncommon to see for these particular services - on the same structure unfused disconnect - meter - fused disconnect - load equipment.

The fused disconnect is the service disconnect. The unfused disconnect on the supply side of the meter is for the POCO and you can not call it the service disconnect even if you would install a fused disconnect there. They will not allow it to have fuses either because the owner/occupant needs to have access to their service overcurrent device(es), but being on supply side of meter POCO places a lock on it so no one will be able to access it and take unmetered power.
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That is correct, but the question was where does the GEC (in this case gnd rods, and water pipe) go to.
 
Hendrix said:
That is correct, but the question was where does the GEC (in this case gnd rods, and water pipe) go to.
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Given what Don stated I would say the service disconnect in the building. I would also say that no egc is required based on the same info.
 
I would put it in the service disconnect but it is allowed at any accessible point ahead of the service disconnect to the service drop or lateral end, 250.24(A)(1). This really is a redundant service switch.
 
IMO, the unfused switch is not part of the premises equipment. I would not be putting the GEC there, even if it was "legal".

How is this any different than the switches the utility sometimes puts on top of the pole at the drop point? I would not run a GEC there either.
 
I do not consider those POCO required "cold sequence" disconnects as service equipment. No separate EGC.
Don referenced an ongoing problem under discussion locally.
The limited (10k) rating of the non-fuse switch is often below the actual available AIC, hover, the switch is considered by some to be under POCO jurisdiction and not NEC. It is an interesting dilemma
 
augie47 said:
I do not consider those POCO required "cold sequence" disconnects as service equipment. No separate EGC.
Don referenced an ongoing problem under discussion locally.
The limited (10k) rating of the non-fuse switch is often below the actual available AIC, hover, the switch is considered by some to be under POCO jurisdiction and not NEC. It is an interesting dilemma
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They are just as much service equipment as a meter socket or other cabinet installed on the supply side of the service disconnect. They must have the grounded service conductor connected to the enclosure. What they are not is the service disconnecting means. They could be service disconnecting means, but most AHJ will not allow it because POCO puts a lock on them making them not accessible to owner/occupant.
 
kwired said:
They are just as much service equipment as a meter socket or other cabinet installed on the supply side of the service disconnect. They must have the grounded service conductor connected to the enclosure. What they are not is the service disconnecting means. They could be service disconnecting means, but most AHJ will not allow it because POCO puts a lock on them making them not accessible to owner/occupant.
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The meter equipment and the meter disconnect are not "service equipment".
Service Equipment. The necessary equipment, usually consisting of a circuit breaker(s) or switch(es) and fuse(s) and their accessories, connected to the load end of service conductors to a building or other structure, or an otherwise designated area, and intended to constitute the main control and cutoff of the supply.
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