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

Wayne Irwin Wayne at PureEnergySolar.net
Sun Mar 15 14:16:54 PDT 2009


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 

Wayne at PureEnergySolar.net 

http://pureenergysolar.net 





From: gilligan06 at gmail.com
To: re-wrenches at 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-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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