point of connection [RE-wrenches]

[Dick Ratico]

Bill,

It is, but mostly it isn't:

I think this is a case of the exception proving the rule, the general rule in
this case being, "A building or other structure
served shall be supplied by only one service."

Article 705.12 specifies where a "parallel power production system" shall be
permitted to be connected:
 "705.12(A) An electric power production source shall be permitted to be
interconnected to the supply side of the service disconnecting means as
permitted in 230.82(6)."

705.12(B) and 705.12(C) permit interconnection of specific types of systems at
different locations elsewhere on the premises. These are the different services
permitted by 230.2(A)(5). The much more common situation permitted by 705.12(A)
is ONE service.

The situation William described is covered by 705.12(A). It is to be considered
one service. And, yes, service conductors can be tapped, see article 230.46.

It would be wonderful if the NEC was more user friendly. I attended your
workshop in Burlington ,VT and greatly admire your work. 

Dick


You wrote:
Dick,

It is:

230.2(A)(5) Parallel power production systems

Also a battery-backup system could also be classified as a separate service,
depending on how it is connected under #4 "Optional Standby Systems"
(Article 702).

Bill.

-----Original Message-----
From: Dick Ratico [mailto:Richard.- at VALLEY.NET] 
Sent: Saturday, May 03, 2008 1:05 PM
To: RE-wre- at topica.com
Subject: RE: point of connection [RE-wrenches]


Bill,

I'm not sure I understand. I think you are saying a grid-tied PV system with
no battery backup is considered by the code (as allowed by Article 230.2(A)
Special Conditions) to be a separate service. It is not among the six Special
Conditions listed.

Dick


You wrote:
In general you are correct, (with few exceptions, e.g. a PV system) but the
NEC permits multiple services under 230.2(A) Special Conditions.

230.2 Number of Services. A building or other structure
served shall be supplied by only one service unless permitted
in 230.2(A) through (D). For the purpose of 230.40, Exception
No. 2 only, underground sets of conductors, 1/0 AWG and
larger, running to the same location and connected together at
their supply end but not connected together at their load end
shall be considered to be supplying one service.
(A) Special Conditions. 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
(6) Systems designed for connection to multiple sources of
supply for the purpose of enhanced reliability

Bill.


William,

My understanding is that the "tap rule" does not apply to supply side
service connections. There is a limitation on the supply side and that is
the service conductor size on the high side and 60-amps on the low side if
the supply is connected to a building. I try be careful to not use the term
"tap" when referring to anything on the Supply side of the service
disconnect. The NEC considers this connection a new service.


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