NEMA Publishes NEMA FB 1 for Fittings, Cast Metal Boxes, Conduit Bodies
August 15, 2007 // Published as a news service by IHS
According to Lon Ballard, a member of NEMA's Conduit Fittings Section, ANSI/NEMA FB 1-2007 is the industry standard for manufacturers of conduit, cable fittings and metal boxes.
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The standard ensures that products function as intended in the field and properly mate with cable and raceway system components. "Compliance with [NEMA] FB 1 also helps manufacturers prepare for safety certification of their products," he said.
According to NEMA, this standard incorporates several significant changes, including new definitions for National Pipe Taper (NPT), negative temperature coefficient (NTC), NTCM and nominal pipe size (NPS) thread forms.
It also rewrites requirements for conduit entries, introduces a conduit fittings industry family tree and includes an appendix for gauging practice.
The standard includes new and revised tables that indicate minimum L1+2 thread engagement; minimum and maximum turns for NTCM threaded conduit entries; minimum depths to integral bushings in a fitting, conduit body, or box having NTC or NTCM threaded entries; and maximum number of threads in a fitting or box wall with through-threaded entries.
NEMA FB 1-2007 covers fittings that are a part of electrical raceway systems and meet requirements of the National Electrical Code (NEC). These include fittings used with non-flexible tubular raceways, as well as flexible conduit and cable raceways that encompass:
- Flexible metal conduits.
- Armored cable.
- Metal-clad cable.
- Tray cable.
- Mineral-insulated cable.
- Flexible cords.
- Nonmetallic sheathed cable.
- Service entrance cable.
ANSI/NEMA FB 1-2007 also includes cast metal outlet boxes as well as conduit bodies and covers.
It excludes fittings, boxes or enclosures that are used in Class I, Division 1; Class II, Division 1; Class III, Division 1; Class I, Zones 0, 1 or 2; and Class II, Zones 20, 21 or 22. There are exceptions for fittings and enclosures that are specifically permitted by NEC.
NEMA FB 1-2007 revises and supersedes NEMA FB 1-2003.