[RE-wrenches] Utility Side Feed In and Disconnects (was "Line Side")

[Drake Chamberlin]

If I understand the issue correctly, the inspector is requiring the 
PV disconnect for the utility feed to be treated as a service.  By 
the definition in Article 100, it can not be a service, and therefore 
should not be subject to the rules of a service.

The definition is quoted below:

Service. The conductors and equipment for delivering electric energy 
from the serving utility to the wiring system of the premises served.

The comment from the NEC Handbook is quoted below:

The definition of service includes the statement that electric energy 
to a service can be supplied only by the serving utility. If electric 
energy is supplied by other than the serving utility, the supplied 
conductors and equipment are considered feeders, not a service.

Energy supplied by an inverter is not coming from a utility.

Drake

At 12:13 PM 3/15/2009, you wrote:
><I just found this sitting in my Drafts folder. Meant to send last week.>
>
>Hi Wayne,
>
>Grouping is a gray area in the NEC. Subject to the discretion and 
>interpretation of the AHJ. Always has been since the concept of 
>grouping was established. Certain conditions and occupancy 
>classifications may allow different interpretations.
>
>Article 230 provides requirements for services. 230.2 Number of 
>Services defines how many services are allowed to supply a building 
>or structure. In general, only one is allowed unless one of several 
>special conditions, occupancies, capacity requirements, or different 
>characteristics are met. 230.2(A) Special Conditions stipulates that 
>"Additional services shall be permitted to supply the following:" 
>(1) Fire pumps; (2) Emergency systems; (3) Legally required standby 
>systems; (4) Optional standby systems; (5) Parallel power production 
>systems; and (6) Systems designed for connection to multiple sources 
>of supply for the purpose of enhanced reliability. If you are doing 
>a non-backup, grid-connected system, your application falls under 
>230.2(A)(5) Parallel power production systems. This is important for 
>a couple reasons, primarily because it specifically allows the 
>second service in the first place. It is also important because, as 
>a Parallel power production system, this is a Special Condition and 
>not a "normal" service.
>
>Requirements for Service Equipment Disconnecting Means are found in 
>Article 230 Section VI. Article 230.70 General specifies that "Means 
>shall be provided to disconnect all conductors in a building or 
>other structure from the service-entrance conductors." (Keep in mind 
>that little word "in".)  Article 230.70 then goes on to list 
>additional requirements for this service disconnect... Readily 
>Accessible outside or inside nearest the point of entry, not in 
>bathrooms, readily accessible again, marked as service disconnect, 
>and suitable for use.
>
>Article 230.71 defines the Maximum Number of Disconnects. 230.71 
>says that the service disconnecting means for each service permitted 
>by 230.2 shall not consist of more than 6 switches or breakers... In 
>a single enclosure, group of separate enclosures, or switchboard. 
>There also shall not be more than 6 sets of disconnects grouped at 
>any one location.
>
>Article 230.72 gives us the Grouping concept. 230.72(A) General 
>says, "The two to six disconnects as permitted in 230.71 shall be 
>grouped. Each disconnect shall be marked to indicate the load 
>served." There is NOT a definition of "grouped".
>
>230.72(B) Additional Service Disconnecting Means specifies that the 
>service disconnect for all of the Special Conditions listed in 
>230.2(A)(1) through 230.2(A)(4) "shall be installed remote from the 
>one to six service disconnecting means for normal service to 
>minimize the possibility of simultaneous interruption of supply." 
>There is no direct mention of 230.2(A)(5) Parallel power production 
>systems. It is unclear to me if this is intentional or 
>unintentional. What is clear to me is that, if for no other reason 
>than the 230.2(A) Special Conditions classification, it is not part 
>of the "normal service".
>
>The explanation in the NEC Handbook (2008) says: The intent of 
>230.2(A) is to permit separate services, where necessary, for fire 
>pumps (with one to six disconnects) or for emergency, legally 
>required standby, or optional standby systems (with one to six 
>disconnects), in addition to the one to six disconnects for the 
>normal building service. Article 230 recognizes that a disruption of 
>the normal building service should not disconnect the fire pump, 
>emergency system, or other exempted systems. Because these services 
>are in addition to the normal services, the one to six disconnects 
>allowed for them are not included as one of the six disconnects for 
>the normal supply. These separate services are permitted by 230.2 
>and are required to be installed in accordance with all the 
>applicable requirements of Article 230.
>
>Notice that the explanation reiterates the "one to six disconnects" 
>per service principle. What is more important is the concept of 
>"remote from the normal service disconnecting means for the purpose 
>of reliability".
>
>A couple of very important elements of the justification for 
>FIT-subsidized DG PV are grid reliability and homeland security. In 
>fact, the location of the DG disconnect in this case should be at 
>the discretion of the interconnecting utility. This is generation, 
>directly to and on behalf of the serving utility. Generation is 
>treated differently than loads by grid operators and rightfully so. 
>In the case of most utility distribution maps, meter locations for 
>loads are mapped whereas generator disconnects are mapped. Note 
>that, unless the customer's meter and service disconnecting means 
>are located adjacent to or grouped with one another, the utility 
>doesn't map (or even care) where the service disconnect is 
>physically located. When you add generation, whether it's 
>utility-side or customer-side connected, they map the generator 
>disconnect. Quite different scenarios. There are fundamental 
>differences between the need and use of each on the part of a utility operator.
>
>In utility-side configurations, the generator is 100% electrically 
>isolated from and independent of the "normal" service. Their 
>respective service disconnects should NOT be "required" to be 
>located adjacent to or grouped with the other. Depending on the 
>actual conditions and arrangements at the site, it may be prudent to 
>provide a permanent placard at each service disconnect showing the 
>location of the other.
>
>Personally, assuming otherwise "normal" conditions and 
>appropriateness of the existing premise electrical system, I would 
>present the AHJ with this rationale and explanation. It may even be 
>prudent to have an earnest conversation with the local utility and 
>see if they are willing to support this position.
>
>Try to find a line-crew somewhere and talk with them about it. Tell 
>them that the local AHJ is trying to make you put the generator 
>disconnect inside the house, next to the existing service 
>disconnect. (This is one of the options the AHJ is presenting you 
>with.) You will get one of two responses... If the person or crew 
>you are speaking with has a jaw full of chew, you will most likely 
>get a macho response like, "Shoot. That dinky solar system ain't 
>gonna hurt us no-how. <spit> We just throw a chain over the line and 
>take it to ground 'til we're done clearing the line. <spit> If your 
>generator ain't ready when we pull the chain, then too bad for you." 
>The other response you will get goes something like this: "They 
>wanna what? Don't they know we don't wanna have to bust down 
>somebody's door to have to lockout the generation? Man, it's our 
>lives at stake out here. Who is this idiot building inspector?" You 
>are far more likely to get the second response from a lone lineman. 
>For some reason, when they are in groups, the macho comes out. I've 
>had this conversation with these guys a few times over the years. 
>For various reasons. It's funny to watch the whole group go from 
>macho to pissed off when one of them says, "Wait a minute... He's 
>right. That building inspector don't know what he's talking about. 
>The customer's load don't have nothing to do with the generation... 
>Generation is our business."
>
>Thought I'd pass it along.
>
>Matt Lafferty
>Solar Janitor
>
>
>----------
>From: re-wrenches-bounces at lists.re-wrenches.org 
>[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Wayne Irwin
>Sent: Wednesday, March 11, 2009 7:56 AM
>To: re-wrenches at lists.re-wrenches.org
>Subject: Re: [RE-wrenches] Line Side Feed In and Disconnects
>
>Wrenches,
>
>They are requiring us to install two service disco's. One for the PV 
>(between the PV and the FIT (payment) meter) and one for the house 
>(between the distribution panel and the standard utility (billing) 
>meter). As Darryl stated, the reason is so that they are grouped 
>together. They said it did not necessarily matter wether or not they 
>were grouped inside or outside, so long as they are grouped.
>We normally install (batteryless) grid tie systems outside with 
>discos within 10' of the utility meter. So as I see it, we must 
>either install the inverter and PV disconnect inside next to the 
>distribution panel, or install an additional disco outside between 
>the house panel and the utility meter, next to the inveter, AC 
>disconnect and FIT meter.
>
>Wayne Irwin
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Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
740-448-7328
740-856-9648  
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