Chapter Corner

600 Volts to 1,000 Volts

Posted in: Code Corner, April 2014

Does the change from 600 volts to 1,000 volts in the 2014 National Electrical Code® (NEC) create confusion? After speaking at several seminars and writing presentations concerning the 2014 NEC changes, it has become very apparent that the change of the voltage threshold from 600 volts to 1,000 volts has many in the industry wondering how or if this affects their industry or market. The answer could be yes or no. This sounds just as confusing as the change in the NEC itself.

First, a little background on how this came about and how it may affect you. At the end of the 2008 code cycle, there was a High Voltage Task Group that was created to review a FPN (now known as Informational Notes) that was deleted from NEC 2008 90.2(A)(2). The 90.2(A)(2) FPN was in the 2005 NEC and had a reference referring the user to ANSI C2 NESC for installations covered by the NEC concerning over 600 volt installations.

This lead to the creation of a new article in the 2011 NEC (Article 399) that reinstated the original 90.2(A)(2) FPN into an Informational Note to Article 399.10 referring the user back to ANSI C2. The High Voltage Task Group was also given direction by the Correlating Committee to review the NEC for need for requirements concerning over 600 volts.

A little historic research behind why the threshold was set at 600 volts in the NEC does not reveal much substantiation. The voltage threshold was increased in the 1920 NEC from 550 volts to 600 volts. No other attempt was made to raise the threshold until the 1990 code. During the 1990 code cycle, there was an attempt to raise the voltage level, however, there was little substantiation provided at the time by the Correlating Committee to raise the threshold.

With the ever changing technology that is presented to the electrical industry, along came wind generation and photovoltaic (PV) systems. The High Voltage Task Group submitted more than 100 proposals for the 2014 NEC to raise the threshold from 600 volts to 1,000 volts in an attempt to keep up with the technological advancement in these technologies. Many PV systems are over 600 volts and the NEC lacked requirements to safely cover these systems. The 600-volt threshold had really never been an issue until the demand and need for sustainable energy resources technology expansion over the recent years. Increasing the voltage threshold alone will not completely cover these systems, however, it does provide a starting point for manufacturers.

Mike Querry holds a Master and Journeyman electrical license in the state of Texas. He also has   a degree in Electrical Technology from Stevens State Tech in Lancaster, Pennsylvania. Querry was previously assigned to NEC Code Making Panel 5 and currently serves on Code Making Panel 17. He is a member of the IEC National Codes and Standards Committee and the Water Environmental Association of Texas. He is employed by The Trinity River Authority of Texas and teaches part-time at IEC Fort Worth/Tarrant County as the fourth-year apprentice instructor, as well as teaching the continuing education curriculum, Master and Journeyman preparation class, and Motor Control classes.