The following questions and answers result from some of the more common situations that many inspectors face throughout their working day when seeing a new PV installation or reviewing a set of plans for a PV system. The questions are simplified versions of questions I receive in e-mails and from questioned plan sets as well as sometimes long, involved phone calls.
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Photovoltaic (PV) power systems are becoming more numerous, larger and more complex. Inspectors and plan reviewers have limited time to deal with these new systems and still carry on the routine electrical system inspections that have been done for 100 years or more. I intend for this “Perspectives on PV” articles to provide you with information on the Code requirements for these systems and also give you information on how to make the plan reviews and inspections easier and faster.
(No Ratings Yet)
There are two areas of PV systems that deserve the attention of inspectors to ensure the safety of the public over these very long periods of time. One is proper grounding of the PV array and the entire system and the other is ensuring that the ac output connections have been properly made to the existing premises wiring. Plan reviewers can look at conductor types with an eye to durability and longevity.
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The NEC in sections 705.12(D) / 690.64(B) allows utility-interactive photovoltaic inverters to be connected on the load side of the service disconnect. This requirement has been in the Code since the late 1980s when PV Article 690 first appeared. Except for a slight change in 2008, the requirement has been largely unchanged. A critical examination of the requirement and how it can be applied as well as various proposals that have been rejected over the years may yield insights on what is needed in the future.
(1 votes, average: 2.00 out of 5)
For nearly a century from about 1897 to 1997, premises wiring systems in residences and commercial buildings have largely been collections of passive conductors, disconnects and overcurrent devices. Certainly there have been incremental improvements in these systems and they can be quite complex with the addition of transformers, motor controllers, GFCIs and AFCIs, but much of that complexity is due to the connected loads that are not covered in inspections under the requirements of the National Electrical Code (NEC).
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Anyone working with PV systems and equipment in either manufacturing, design, installation, or inspection arenas should get a copy of the 2011 NEC and the 2011 NEC Handbook.
(2 votes, average: 4.00 out of 5)
Conductor sizes and overcurrent device ratings are critical to the safe, long-term operation of any electrical system, but are of particular importance in PV systems where the outdoor environment can be extreme and the PV modules will be sourcing current for 40 years or more.
(5 votes, average: 4.80 out of 5)
Inspectors and installers continue to puzzle over the requirements in Section 690.64 of the NEC that apply to the connection of utility-interactive inverters to the premises wiring and finally to the utility. This article, using the simplified block diagram will attempt to clarify some of those requirements.
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A Little History Actually the United States is catching up to the rest of the world, which has, for the most part, been using ungrounded electrical systems for as long as the U. S. has been using grounded electrical systems. More than 100 years ago, the debate on grounded vs. ungrounded electrical systems began and the U. [...]
(2 votes, average: 3.50 out of 5)
In the course of daily business, I get some questions repeated many times. I try to address these areas of common and frequent interest in this series of articles, but there are always a few that need clarification or repeating. Inverter DC Grounding Electrode Conductor In the “Perspectives on PV” in the September-October 2009 IAEI [...]
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IAEI, as the keystone of the electrical industry, is a membership driven, non-profit association promoting electrical safety throughout the industry by providing premier education, certification of inspectors, advocacy, partnerships and expert leadership in Electrical Codes and Standards development.
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