Thanks Matt!
You bring up some very strong points. I will see if I can get the local AHJ to
see the light.
I won't expect any change in his interpretation, but I'm sitting here with the
code book and it seems pretty clear to me.
I have to at least try.
I'll let you know how it goes.
Thanks Again.
Wayne Irwin, President
Pure Energy Solar International Inc.
Lic # CVC56695
wa...@pureenergysolar.net
http://pureenergysolar.net
From: gilliga...@gmail.com
To: re-wrenches@lists.re-wrenches.org
Date: Sun, 15 Mar 2009 10:13:29 -0700
Subject: Re: [RE-wrenches] Utility Side Feed In and Disconnects (was "Line
Side")
<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-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Wayne
Irwin
Sent: Wednesday, March 11, 2009 7:56 AM
To:
re-wrenches@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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