By Marty Brett on Wednesday, 01 August 2012
Category: National Electric Code

Do You Make This Mistake? Elbows, Couplings and Nipples Are Not Fittings

When you are dealing with codes and standards you learn how important it is to choose the proper words. The Code requirements are what products are evaluated against to be “listed for the purpose.” And the Listing standard determines the testing of a product to evaluate its suitability for the installation and use in conformity with the Code (Article 110). Quite often products are specified with a reference to the Listing Standard because the listing is very specific to the tests and procedures used to conduct the product evaluation. The specifier or designer is assured that the product listed to the standard has the properties needed to comply with the Code and installed performance requirements. These standards ensure that products function as intended in the field and properly mate with cable and raceway system components.

An ongoing problem in specifying our products is the use of the term “fitting” in conjunction with the threaded conduit nipples, or threaded or unthreaded factory made elbows and threaded couplings for use with Rigid and Intermediate Metal Conduit or Electrical Metallic Tubing. It is misleading as to what standard they may be listed to and therefore, their suitability for some applications in the Code.

The listing standards applicable to Rigid Metal Conduit (RMC), Intermediate Metal Conduit (IMC) and Electrical Metallic Tubing (EMT) are UL 6, 1242 and 797 respectively. The scopes (Clause 1.1) of these standards include nipples, elbows and couplings with the exception of EMT which only includes elbows. These items are not considered “fittings” except for the integral couplings I will address later.

The listing standard for the “fittings” used with these raceways is the Standard for Conduit, Tubing and Cable Fittings, UL 514B. The reference to fittings within the above mentioned raceway standards is to connectors, couplings, hubs, bushings, etc. that are listed to UL 514B as noted in the standard. These are made from die-cast, iron, malleable iron material or non-metallic materials and are used to provide additional properties required by the system design or simply to join straight sections.  A good example would be EMT which has straight section and elbows listed to UL 797 but no component to join them to create a system.In the case of RMC and IMC fittings “listed for the purpose” are need to connect to a box, enclosure or transition to another raceway type or conduit which are not provided for under their listing. Fittings listed under UL 514B are needed.

The three National Electrical Code® (NEC®) Articles that specifically address the requirements, permissions and limitations of our products are 342 Intermediate Metal Conduit, 344 Rigid Metal Conduit and 358 Electrical Metallic Tubing. In Part I. General, of each Article, you have a Scope Section XXX.1, Definition Section XXX.2 and the Listing Requirements Section XXX.6. The XXX is a place holder the applicable Article number. These Articles, of course, can be and often are modified by other sections of the Code.

In the Scope and Listing Requirements sections the phrase “associated fitting” is used and is intended to refer to those nipple, elbows and couplings which are not made from Rigid Metal Conduit, Intermediate Metal Conduit or Electrical Metallic Tubing. They are not the ones listed to the applicable UL raceway standard.In the definition for RMC and IMC a reference is made to an “integral coupling” and “appropriate fittings.” In section 358.100 Construction of the EMT article, a reference is made to an “integral coupling.” These are couplings that are made and affixed to the RMC or IMC and not intended to be sold separately and therefore, integral to the raceway. In the case of EMT, one end of the tubing is expanded and additional components added to provide a compression or set-screw coupling. These couplings are evaluated under and listed to UL 514B. The raceway must still comply with the appropriate raceway standard.

I think some confusion may stem from the use of “associated” fittings in the scope of RMC and IMC and “associated” coupling under definition. As conduit producers we know that our elbows, couplings and nipples are not fittings. Therefore, the “associated fittings” referenced in the scope are those other than elbows, couplings and nipples listed to the raceway article.But the definition contains the phrase, “…when installed with its integral or associated coupling and appropriate fittings.” In this case “associated coupling” is the one listed to the raceways article and the “appropriate fittings” are those other than elbows, couplings and nipples listed to the raceway article. If “appropriate fittings” where used instead of “associated fittings” is may reduce the confusion. It is very tempting to just refer to the elbows, couplings and nipples as fittings but it would not be correct. To support that statement let’s look at what UL 514B and NEMA FB 1 say about the nipples, elbows and couplings associated with the raceways.

The Scope of UL 514B Conduit, Tubing, and Cable Fittings states in Clause 1.6, “These requirements do not cover conduit NIPPLES, threaded ELBOWS, and threaded COUPLINGS intended for use with rigid metal conduit, intermediate metal conduit, or electrical metallic tubing.” Clause 1.4 restricts 514B fitting from use in hazardous location and states that, “These requirements do not cover FITTINGS intended for use in hazardous locations as defined in the National Electrical Code, ANSI/NFPA 70, the Canadian Electrical Code (CEC), Part I, CSA C22.1, and the Standard for Electrical Installations, NOM-001-SEDE.”

An American National Standards Institute (ANSI) standard published by the National Electrical Manufacturers Association (NEMA) ANSI/NEMA FB 1, Fittings, Cast Metal Boxes, and Conduit Bodies for Conduit, Electrical Metallic Tubing, and Cable is often cited in designer specifications. However, as stated in the standard, “This standard does not include standard conduit couplings of the type provided with lengths of Rigid and Intermediate Metal Conduit, or threaded conduit nipples, or threaded or unthreaded factory made bends derived from Rigid and Intermediate Metal Conduit or Electrical Metallic Tubing.”  FB 1 also limits use in hazardous classified location. It says, “This standard does not apply to fittings, boxes or enclosures that are for use in Class I, Division 1; Class II, Division 1; Class III, Division 1; Class I, Zones 0, 1, 2; Zones 20, 21, or 22 hazardous (classified) locations.”

In summary, fittings are not those that are listed to the raceway standard but those listed to UL 514B.

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