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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.<br><br>
The definition is quoted below: <br><br>
<u>Service. The conductors and equipment for delivering electric energy
from the serving utility to the wiring system of the premises
served.<br><br>
</u>The comment from the NEC Handbook is quoted below: <br><br>
<u>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.<br><br>
</u>Energy supplied by an inverter is not coming from a utility.
<br><br>
Drake <br><br>
At 12:13 PM 3/15/2009, you wrote:<br>
<blockquote type=cite class=cite cite=""><font color="#0000FF"><I just
found this sitting in my Drafts folder. Meant to send last week.><br>
</font> <br>
<font color="#0000FF">Hi Wayne,<br>
</font> <br>
<font color="#0000FF">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. <br>
</font> <br>
<font color="#0000FF">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
<b><u>not</u></b> a "normal" service. <br>
</font> <br>
<font color="#0000FF">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." <i>(Keep in mind that little word
"in".)</i> 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. <br>
</font> <br>
<font color="#0000FF">Article 230.71 defines the Maximum Number of
Disconnects. 230.71 says that the service disconnecting means for
<b><u>each service</u></b> 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.<br>
</font> <br>
<font color="#0000FF">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".
<br>
</font> <br>
<font color="#0000FF">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 <b><u>not</u></b> part of the
"normal service". <br>
</font> <br>
<font color="#0000FF">The explanation in the NEC Handbook (2008) says:
<i>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.<br>
</i></font> <br>
<font color="#0000FF">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". <br>
</font> <br>
<font color="#0000FF">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.<br>
</font> <br>
<font color="#0000FF">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. <br>
</font> <br>
<font color="#0000FF">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.<br>
</font> <br>
<font color="#0000FF">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 <b><u>inside the house</u></b>, next to the existing
service disconnect. <i>(This is one of the options the AHJ is presenting
you with.)</i> 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, <i>"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."</i> The other response you will get goes something like this:
<i>"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?"</i>
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, <i>"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." <br>
</i></font> <br>
<font color="#0000FF">Thought I'd pass it along.<br>
</font> <br>
<font color="#0000FF">Matt Lafferty<br>
Solar Janitor<br>
</font> <br>
<hr>
<font face="Tahoma"><b>From:</b>
re-wrenches-bounces@lists.re-wrenches.org
[<a href="mailto:re-wrenches-bounces@lists.re-wrenches.org" eudora="autourl">
mailto:re-wrenches-bounces@lists.re-wrenches.org</a>] <b>On Behalf Of
</b>Wayne Irwin<br>
<b>Sent:</b> Wednesday, March 11, 2009 7:56 AM<br>
<b>To:</b> re-wrenches@lists.re-wrenches.org<br>
<b>Subject:</b> Re: [RE-wrenches] Line Side Feed In and Disconnects<br>
</font><br>
Wrenches,<br><br>
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. <br>
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.<br><br>
Wayne Irwin <br>
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<x-sigsep><p></x-sigsep>
Drake Chamberlin<br>
Athens Electric<br>
OH License 44810<br>
CO License 3773<br>
740-448-7328<br>
740-856-9648 </body>
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