Switched Emergency Lighting?

Status
Not open for further replies.
B

bcorbin

Senior Member
In a conference room, is it allowed to feed a switched lighting circuit from an emergency source? This would seem to defeat the purpose of the emergency lighting, i.e., the power goes out during a presentation, when all the lights are already intentionally switched off. Now the room will be in total darkness until someone finds for the switch.

Am I simply forced to use a battery backup fixture even with emergency power available?
 
I believe that's okay.

If you're concerned about it, you could always use some contactors to override the function of the wall switches in the event of a power outage. Or provide some accent lighting that has no switches to throw some illumination into the room to find the switches.
 
There are devices which work for this situation that are 924 compliant. One manufacturer's device acts like a mini transfer switch while another works like a lighting contactor. The difference between them is the load for the emergency lights during normal power conditions is feed from the non-emergency panel with the first device and from the emergency panel for the second device. Make sure you check the amp rating on the devices when you specify it.

Both devices allow the em lights to be switched with other non-em lights in the room but when the power fails the devices ignor the switch position and turn the em lights on. Expect to pay around $100 per device.
 
If there is one or two locations like this, you could just opt for an emergency battery if you are using fluorescents, or the $35 EM unit.
 
I don't know why you'd need any emegency lighting if your generator responds within 10 seconds. Whether the room is on normal or emergency power, the inhabitants have to stumble for the light switch, and when they find it the lights will come on. Maybe I'm missing something.

Jim T
 
The room occupants don't need to stumble for a light switch. They will have to wait the 10 seconds for the generator to start. These devices are wired similar to a battery pack with wiring to both the load and supply side of the switch. When it detects a lack of power on the supply side of the switch it will turn on the em lights. The main wiring difference is a third set of wires to the emergency panel. One device can control multiple lighting fixtures as long as its amp rating isn't exceeded.

It took me some time to understand these devices. It's even more fun trying to show the wiring on a lighting plan.
 
Code wise , how can you put 2 seperate circuits from 2 seperate sources into one fixture? That is if I read all this correctly. Just a thought.
 
Sass5150 said:
Code wise , how can you put 2 seperate circuits from 2 seperate sources into one fixture? That is if I read all this correctly. Just a thought.
Click to expand...

See 700.9(B)(2)

Roger
 
jtester said:
Whether the room is on normal or emergency power, the inhabitants have to stumble for the light switch, and when they find it the lights will come on. Maybe I'm missing something.

Jim T
Click to expand...

To clarify (and add info I probably should have included originally :wink: ), I am just trying to compare battery-fed lighting fixtures, which come on instantly, even if switched off, for an owner who has already spent big dollars on a generator and UPS and thought he wouldn't have to buy and maintain lighting fixture batteries. In a room where the only light (sometimes) will come from a lit projection screen (which is obviously not on emergency power), the 10-second wait is a level-of-design issue.

Thanks for all the great info, guys. :)
 
Status
Not open for further replies.
Top