Can Emergency and Optionally Standby Lighting Circuits Be Controlled by a Single Switch?

[Goldfish619]

Hello All,

I have a situation where a classroom has a single switch that needs to control both optionally standby and emergency lighting circuits. The entire campus is backed up by either emergency or optionally standby power. Since I need to have that single switch control both circuits, can I use UL924 relay to control both circuits ahead of the switch and bring emergency lighting to full brightness regardless of switch position? Typically, this would be done on a normal and emergency circuits. So, my question is, will the relay know when optionally standby power kicks in within 60 secs that it's not the "normal" power and keep the emergency lights on or will it shut off the emergency lighting thinking hey "normal" power has return.

If this setup cannot work, what can I do to control both circuits and have the emergency lighting be turned on regardless of the switch situation? I was thinking of having a double pole, double throw switch so it can have two separate circuits to the switch and turn on both light circuits. I would then have the UL 924 relay ahead of the switch only for the emergency circuit. I am just not sure if you can combine optionally standby and emergency circuits on the double pole, double throw switch and not violate any code.

Any clarifications or suggestions would be very helpful. I know some hospitals have their systems setup to be backed up all the time as well, wonder if anyone has encountered this type of situation in the past and figured how to go about it. Thank you in advance.

 

[SpaceNeedle46]

You need normal constant to make this work. You can use a regular single pole switch or achieve the same results with a wireless switch and power packs/lighting control relays. In either case you will need a normal constant and two UL-924 devices.

Using a single pole switch, you’d feed the switch with normal constant. The normal switch leg will feed one UL-924 for the optional standby fixtures and one UL -924 for the emergency fixtures.

The optional standby UL-924 will receive the normal constant, normal switch leg created by the switch, standby constant, and create the standby switch leg that will feed the standby fixtures.

The emergency UL-924 will receive the normal constant, normal switch leg created by the switch, emergency constant, and create the emergency switch leg that will feed the emergency fixtures.