Emergency lighting relays in California are often selected based on their UL924 listing. Their use in an emergency system is governed by NEC 700 (the national standards used elsewhere), alongside Title 24's automatic lighting control requirements. A UL924-listed automatic load control relay (ALCR) forces emergency fixtures on at full output when normal power is lost, overriding any local control that would otherwise keep them off. Functional Devices, Inc. builds UL924-listed RIB® (Relay-In-a-Box®) relays for that purpose.
UL924 and NEC 700 Requirements
UL924 covers emergency lighting control at the branch circuit level. NEC 700.26 permits the use of an automatic load control relay (ALCR); it does not require one. NEC 700.3 covers the periodic testing requirements that apply to emergency systems. The code language sets what the emergency lighting must do, not which device does it, so device selection comes down to the control scheme and the load.
In a typical configuration, the relay sits between the normal lighting control and the emergency load: under normal power the fixture follows its usual switches, sensors, or dimmers, and when normal power drops the relay forces the fixture on at full brightness regardless of those controls.
How Title 24 Lighting Controls Interact
Title 24 Part 6 requires automatic lighting controls in California commercial spaces: occupancy sensing, automatic shutoff, and multilevel dimming among them. Title 24 does allow designated means-of-egress lighting to stay continuously on without those controls, within limits; but keeping emergency fixtures always-on is inefficient, so they are commonly placed under the normal lighting controls instead.
Once an emergency fixture is controlled that way, NEC 700 requires a mechanism that overrides the control and drives the fixture to full output when normal power is lost. A UL924 ALCR is that mechanism: it lets the fixture operate as normal, energy-code-controlled lighting day to day and forces it on during an outage.
Functional Devices UL924 Relays
Functional Devices offers a range of UL924-listed emergency lighting relays:
- The ESRN-U is the right device when the emergency fixture must be controlled with the surrounding normal lighting. It is a 20A SPST ALCR with universal 120–277 Vac input, 0–10 Vdc dimmer override, and a dry contact fire alarm interface, with a built-in test button and LED indicators for commissioning and inspection.
- The ESRB provides the ESRN's emergency function in a ballast-channel mount, which suits retrofit work and shallow enclosures.
- The ESRLBC uses a slim enclosure for linear lighting and fixture-mount installations, adding an isolated relay loop to break standard 0–10 Vdc dimming circuits, forcing the fixture to full brightness.
- For a simpler shunt or bypass rather than a full ALCR, the ESR2401B (120 V) and ESR2402B (277 V) provide 20A UL924-listed switching to force a light on when normal power drops.
In a California office where egress fixtures are dimmed and occupancy-controlled under Title 24, an ESRN lets those fixtures run on the normal controls and forces them to full output on loss of normal power, with the dry contact interface available to tie into the fire alarm panel. The built-in test button and LED indicators let an inspector confirm the transfer locally during acceptance testing, without de-energizing the floor.
Frequently Asked Questions
Does California require a UL924 relay for emergency lighting?
NEC 700.26 permits an automatic load control relay rather than requiring it. A UL924-listed device is the appropriate and most commonly specified way to control emergency fixtures alongside normal lighting. Confirm requirements with the Authority Having Jurisdiction.
What is the difference between an ALCR and a bypass/shunt relay?
An ALCR such as the ESRN gives full control of the emergency fixture with the normal lighting and forces it on during an outage. A bypass/shunt relay such as the ESR2401B is a simpler device that overrides a local switch to force the light on when normal power is lost.
Source UL924 Emergency Lighting Relays in California
For emergency lighting on a California project, the UL924-listed RIB® relays covered here—the ESRN-U, ESRB, and ESRLBC, plus the ESR2401B and ESR2402B bypass/shunt models—are stocked through authorized Functional Devices distributors statewide, with local availability across Los Angeles, the Bay Area, San Diego, and Sacramento. An authorized distributor can confirm the exact model and coil voltage for the application before specifying. Browse the RIB® relay lineup, or find an authorized Functional Devices distributor in California.