Possible to control Egress lighting fed from generator with Normal lights?


I'm stuck; please help.
I have a space where the lighting needs to be controlled automatically via lighting contactor and time clock for scheduled ON/OFF with local dimming controls (its a treatment room in a Dialysis center). We have an standby generator for life safety and optional emergency power. Some of the 2x4 fixtures in the treatment room are designated as Egress and therefore are to be fed from the life safety branch panel. However, I want/need to be able to control these egress 2x4 fixtures with the normal fixtures in the space for dimming purposes. I was thinking an UL924 emergency lighting control relay would suffice but I don't see how this will override the time clock in the event of an outage during OFF hours. Any thoughts or better ideas on how to feed these fixtures?

We are not interested in using occupancy sensors in this treatment room. Although there will be people in the space during the majority of the day, the patients and nurse's often sit still for long periods of time and we don't want the fixtures turning on/off during the day. I have a similar problem in the waiting area.



New Jersey
A ul924 relay will work just fine. It's designed to work in this exact scenario. The relay gets both normal power and life safety power. When normal power fails, the voltage to the coil in the relay is lost and is therefore overridden.


Senior Member
You would need a branch circuit emergency lighting transfer switch (BCELTS)

See the article at for a good discussion.


"ALCRs are covered by 700.26 in the 2017 edition of the NEC and Listed to UL 924, Emergency Lighting and Power Equipment, under Category FTBR. Whether or not they appear to have transfer functionality, they are suitable only to bypass switches or control equipment fed from a single normal/emergency source, not to transfer between normal only and normal/emergency sources. The normal/emergency source must be provided via an upstream emergency transfer switch."