Fw: Service Entrance Taps-Potential Problem [RE-wrenches]

[Allan Sindelar]

Service Entrance Taps-Potential ProblemWrenches,
Forwarding this message at the request of John Wiles. 
Allan Sindelar, Positive Energy

----- Original Message ----- 
From: John Wiles 


Service Entrance Taps-Potentially Overloaded Conductors


NEC Section 690.64 and Article 230 allow the service entrance conductors to be tapped for a limited number of uses including the connection of a PV system.


The installer should note that any connection at this point may increase the load on the service entrance conductors (to the utility transformer) and that load may be as high as the rating of the added service disconnect overcurrent device.  The service entrance conductors must be rated and capable of handling this potentially added load.  The added load may come from: 
- the power required to charge batteries in a battery-backed-up, utility-interactive system; 
- loads added to any ac PV combiner panel;
- added loads on a protected load panel that were not on the original panel;
- or a fault in the lines to the PV equipment.


It is the responsibility of the installer to assess the existing loads and these added loads (limited by the added overcurrent device) according to the requirements of Article 220 in the NEC and then determine if the existing service entrance conductors are adequate or need to be replaced.
-- 
Visit the SWTDI Codes and Standards web site http://www.nmsu.edu/~tdi/Photovoltaics/Codes-Stds/Codes-Stds.html  for more information.  You will be able to download the latest pdf (version 1.6) of the 149 page "PV Power Systems and the 2005 National Electrical Code: Suggested Practices" Manual in full color.  We are no longer printing these manuals.  Also see the "Perspectives on PV" articles (written for electrical inspectors) and the "Code Corner" articles (written for Home Power Magazine). The web site also has the future schedule for the 6-8 hour "PV and the NEC" presentations.

If I can provide further information, please do not hesitate to call, e-mail or fax me.

John

John C. Wiles,  Program Manager
Southwest Technology Development Institute, New Mexico State University
505-646-6105      505-646-3841 (FAX)   http://www.NMSU.Edu/~tdi
AREA CODE Changes to 575 on Oct 7, 2007
SWTDI/NMSU
3705 Research Drive
Box 30001/MSC 3 SOLAR
Las Cruces, NM 88003-8001
[Non-text portions of this message have been removed]


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