Single battery for multiple emergency lights

Status
Not open for further replies.
S

sfav8r

Senior Member
Location
San Francisco Bay Area
We have an installation where there are about 6 light fixtures in a stairwell. There is currently no emergency lighting. The city inspector during his annual rounds noted the lack of egress lighting and the client called us to install additional fixtures with battery backup. In looking at the current installation, the stairway fixtures are all fed from a separate conduit with a single circuit. It seems like a pretty simple fix to just add a battery backup at the timer for the stairway lights. I believe this installation would not allowed if there were other circuits in the conduit, but since the only circuit is for the lights, it seems this should be OK. Does anyone disagree? Does the conduit need to be marked somehow since it would have power, at least temporarily, even with the power shut off to the building? Also, we have calculated the size backup required to run the lights for 90 minutes. Is our calculation good enough or is that something UL or someone else would have to verify which would obviously make this option a irrelevant.

Thanks
 
You can use a UL listed emergency inverter for this.

The only issue I can see and I doubt it would come up is that typicaly not every fixture is required to be egress lighting and you are not supposed to add optional loads to emergency circuits. But seriously, six lights in a stairway, it seems like it would be fine.


Now that said, I bet the inverter costs far more than six battery units and the labor to install them.
 
90 minutes run time sounds correct, however I would make sure that figure can easily be met 5 years down the road as well.

Battery back up e-lights or e-light/EXIT sign combos with LED lights arent terribly expensive, and if one battery fails you still have 5 more. A master backup, if it fails, will wipe all of your stairwell lights, and like iwire mentioned, would probably cost more than 6 individual units. Here are some for $19ea:

https://www.1000bulbs.com/product/9...m9ObcwZrlaDI3lo-ahXinQHMC6_KlLgJqvBoC29Lw_wcB
 
Thanks for the input. It was more of an aesthetics thing, but at $20ea. it is quite a price difference. Although there is the issue of getting constant power to all 6 fixtures as well. It's good to have options.
 
If you put a single battery backup at the timer, I don't think the timer would be listed for use on an emergency circuit.

But that's not an issue if you use the individual emergency lights.

Is there some type of night lighting, or do all the lights in the stairwell turn off with the timer?
 
What you're doing certainly sounds reasonable but there are a number of more strict requirements for life safety circuits. Here are two that come to mind:
  1. I believe you'd need a UL 924 bypass relay to bypass the timer if power failed, like this: http://www.hubbell-automation.com/products/bypass_shunt_relays. This ensures the lights turn on if building power is lost. We use them for switched emergency light circuits on a generator circuit.
  2. NEC 517.30 doesn't allow emergency lighting branch circuits in MC/Romex, they must be rigid conduit.
 
greenspark1 said:
What you're doing certainly sounds reasonable but there are a number of more strict requirements for life safety circuits. Here are two that come to mind:
  1. I believe you'd need a UL 924 bypass relay to bypass the timer if power failed, like this: http://www.hubbell-automation.com/products/bypass_shunt_relays. This ensures the lights turn on if building power is lost. We use them for switched emergency light circuits on a generator circuit.
  2. NEC 517.30 doesn't allow emergency lighting branch circuits in MC/Romex, they must be rigid conduit.
Click to expand...


That's hospitals. Not sure if OP is working on one or not, but good point.
 
700.12 General Requirements. (F) Unit Equipment. Individual unit equipment for emergency illumination shall consist of the following: Emergency luminaires that obtain power from a unit equipment and are not part of the unit equipment shall be wired to the unit equipment as required by 700.9 and by one of the wiring methods of Chapter 3.


Are you saying the same conductors that normally supply the fixtures will be in the same conduit as conductors that supply battery back up to the emergency fixtures?

700.3 Equipment Approval.
All equipment shall be approved for use on emergency systems.


700.9 Wiring, Emergency System.

(B) Wiring. Wiring of two or more emergency circuits supplied from the same source shall be permitted in the same raceway, cable, box, or cabinet. Wiring from an emergency source or emergency source distribution overcurrent protection to emergency loads shall be kept entirely independent of all other wiring and equipment, unless otherwise permitted in (1) through (5):
(1) Wiring from the normal power source located in transfer equipment enclosures
(2) Wiring supplied from two sources in exit or emergency luminaires
(3) Wiring from two sources in a common junction box, attached to exit or emergency luminaires
(4) Wiring within a common junction box attached to unit equipment, containing only the branch circuit supplying the unit equipment and the emergency circuit supplied by the unit equipment

III. Sources of Power
700.12 General Requirements.
a(A) Storage Battery. Storage batteries used as a source of power for emergency systems shall be of suitable rating and capacity to supply and maintain the total load for a minimum period of 11/2 hours, without the voltage applied to the load falling below 871/2 percent of normal.
Batteries, whether of the acid or alkali type, shall be designed and constructed to meet the requirements of emergency service and shall be compatible with the charger for that particular installation.
 
Status
Not open for further replies.
Top