NEMA Releases Revised Panelboard and Distribution Switchboard Standards

By Consulting Specifying Engineer Staff June 19, 2006

The Low Voltage Distribution Equipment Panelboard and Distribution Board Product Group of the National Electrical Manufacturers Assn. (NEMA), recently published two revised standards covering panelboards and distribution switchboards: PB 1-2006, Panelboards and PB 2-2006, Deadfront Distribution Switchboards. These are the first revisions of the two standards since 2000 and 2001, respectively.

PB 1-2006 is a general standard for panelboards providing information on panelboard types, voltage ratings, short-circuit current ratings, construction requirements and test procedures.

PB 2-2006 covers floor-mounted deadfront switchboards rated 6,000 amps or less, 600 volts or less and consist of an enclosure, molded case circuit breakers, low-voltage power circuit breakers, fusible or non-fusible switches, instruments, metering equipment, monitoring equipment or control equipment, with associated interconnections and supporting structures. These units are used in the distribution of electricity for light, heat, and power.

“PB 1 and PB 2 provide a common understanding within the electrical community for the purchase, testing, application and use of panelboards and switchboards,” says Kevin J. Lippert, chairman of the NEMA LVDE 02 Panelboard and Distribution Board Product Group. “This is very helpful for manufacturers, specifiers and users of these products. Changes to these documents include updates of references to the latest edition of other referenced codes and standards. In addition, the enclosure type designations were modified to reflect the most recent terminology in NEMA 250.”

PB 1-2006 may be viewed or purchased at . PB 2-2006 may be viewed or purchased at .