Dual circuit Exit signs

[Hot Louie]

Are all exit signs required to have dual circuits (1 normal power, 1 generator power) when generator is available or required in building?
This is for a school.
Thanks
:smile:

 

[Dennis Alwon]

I have never seen an NEC code which requires a generator for exit lights. There are battery backup exit lights. Most schools don't have a generator so how could they require it??

I hope you have an electrical contractor doing the work.

 

[raider1]

The requirement for emergency power comes from the building codes. I would check with your local building department for their requirements.

Here is what the 2006 IBC says in regards to exit sign power:

1011.5.3 Power source. Exit signs shall be illuminated at
all times. To ensure continued illumination for a duration of
not less than 90 minutes in case of primary power loss, the
sign illumination means shall be connected to an emergency
power system provided from storage batteries, unit equipment
or an on-site generator. The installation of the emergency
power system shall be in accordance with Section
2702.
Exception: Approved exit sign illumination means that
provide continuous illumination independent of external
power sources for a duration of not less than 90 minutes,
in case of primary power loss, are not required to be connected
to an emergency electrical system.

This section allows you to use storage batteries, unit equipment, or an on-site generator.

Chris

 

[steve66]

I think there are basically four options for exit signs:

1. Normal power only (usually from a utility).
2. Normal power with battery backup.
3. Dual power, one normal utility and one from a generator.
4. Single circuit. In this case, the single circuit is often supplied from an automatic transfer switch, which in turn has a utility feed and a generator feed.

Local and National codes may restrict which one you use. I don't know of anywhere where #1 is allowed. Our local City requires #2 in some areas. I guess they don't trust a backup generator.

 

[russ]

I think the normal situation would be all of your emergency circuits, (EM lights and exits) should be out of a separate panel, fed from a transfer switch. The transfer switch would be fed from "normal" power first, and then the generator upon failure of the normal power.
I Haven't seen an exit with two sets of 120v lights that would be fed from two different sources. Do they exist?

 

[ramdiesel3500]

Not sure about exits signs, but we are just now beginning to see light fixtures on electrical plans that have an internal PTS (power transfer switch) relay unit. This unit allows the fixture to be dual fed. The idea behind this is so that when on normal power, the fixture is fed from a switch leg and can be turned off by the occupant. The PTS relay coil is fed by unswitched normal power. The normal power from the switchleg is connected to the normally open contacts on the PTS relay. A standby power circuit feeds the normally closed contacts. So, when normal power is available the normal power contacts are closed and the fixture is controlled by the toggle switch on the wall. When normal power is lost, the relay coil de-energizes opening the normal power contacts and closing the emergency power contacts thereby connecting the fixture (unswitched) to the standby power panel.

 

[Hot Louie]

Thanks for the info, my concern is that I provided exit signs from the generator emergency panel only. which I believe to be sufficient. I hospitals there is a dual circuit requirement and I don't know if it applies to other buildings when a genset is available.
Luis