Change Summary

• A new 700.25 titled, “Branch Circuit Emergency Lighting Transfer Switch” was added to allow these devices to be used to transfer emergency lighting loads supplied by branch circuits rated at not greater than 20-amperes from the normal branch circuit to an emergency branch circuit. A new definition for Branch Circuit Emergency Lighting Transfer Switch was also added at 700.2.

Expert Analysis

For the 2017 NEC, a new section was added to Article 700 at 700.25 titled, “Branch Circuit Emergency Lighting Transfer Switch.” This section permits emergency lighting loads supplied by branch circuits rated at not greater than 20-amperes to be transferred from the normal branch circuit to an emergency branch circuit using a listed “branch circuit emergency lighting transfer switch.” The product standard for this new class of transfer switching devices can be found in UL 1008 (Transfer switch Equipment).

In some past situations, an automatic load control relay (ALCR) has been used to transfer emergency lighting loads from the normal supply to an emergency supply (even though this is a code violation of 700.26). During the 2011 NEC, 700.24 (now 700.26 in the 2017 NEC) was added to the Code. This section covers the requirements for ALCRs and specifically states, “the load control relay shall not be used as transfer equipment.” UL 924 (Standard for Emergency Lighting and Power Equipment) transfer-capable ALCRs were never intended for use as general purpose transfer equipment. However, these devices fall within the NEC definition of transfer equipment because they can be used for transferring a load between two asynchronous power sources (normal and emergency). Even if they do meet the definition of transfer equipment, they do not meet the current requirements of Article 700 for emergency transfer switches. ALCRs have not undergone any evaluation as emergency transfer switches.

This is part of the reason it was necessary for these new branch-circuit emergency lighting transfer switches toe introduced into the 2017 NEC. These devices (and transfer-capable ALCRs that are re-evaluated as branch ircuit emergency lighting transfer switches underUL 1008) will now be evaluated using performance and construction requirements comparable to those applied to traditional emergency transfer switches for use on branch circuits rated up to 20-amperes.

Leviton offers Emergency Transfer Switches only as part of a complete systems solution. For additional details about having a Leviton Solution designed and quoted for your project, please reach out to your local Leviton lighting controls representative. A list of lighting control representatives can be found by clicking on the ‘Find a Sales Representative’ link at Leviton.com/architecturalcontrols. Or you can call 1-800-959-6004, or email us at lestechsupport@leviton.com.