Battery Units on Generator, or not?

[iggy2]

We are designing a STANDBY power system for a community building. The SPS will power everything except the laundry and the electric water heater. The SPS will power all the normal lighting. There are battery units for egress lighting. There is no emergency power system. The presumption is that the community building will be used by local residents to gather in the event of an extended power outage, since their apartment electric heat/cooking/lighting will be out.

Should the battery units be powered by the generator, or no???

If powered by the generator, the battery units will turn off as soon as the transfer switch transfers - and there will be no egress lighting. (Of course, the 'normal' lights will be on, but they will not be powered from an emergency system.)

If not powered by the generator, on a power failure, the battery units will run for 90 minutes, then die, and again - there will be no egress lighting.

This is in MA, so 2009 IBC is in effect.

"1006.1 Illumination required. The means of egress, including the exit discharge, shall be illuminated at all times the building space served by the means of egress is occupied."

"1006.3 Illumination emergency power. The power supply for means of egress illumination shall normally be provided by the premises' electrical supply. In the event of a power supply failure, an emergency electrical system shall illuminate all of the following areas:..."

 

[david luchini]

We are designing a STANDBY power system for a community building. The SPS will power everything except the laundry and the electric water heater. The SPS will power all the normal lighting. There are battery units for egress lighting. There is no emergency power system. The presumption is that the community building will be used by local residents to gather in the event of an extended power outage, since their apartment electric heat/cooking/lighting will be out.

Should the battery units be powered by the generator, or no???

If powered by the generator, the battery units will turn off as soon as the transfer switch transfers - and there will be no egress lighting. (Of course, the 'normal' lights will be on, but they will not be powered from an emergency system.)

If not powered by the generator, on a power failure, the battery units will run for 90 minutes, then die, and again - there will be no egress lighting.

This is in MA, so 2009 IBC is in effect.

"1006.1 Illumination required. The means of egress, including the exit discharge, shall be illuminated at all times the building space served by the means of egress is occupied."

"1006.3 Illumination emergency power. The power supply for means of egress illumination shall normally be provided by the premises' electrical supply. In the event of a power supply failure, an emergency electrical system shall illuminate all of the following areas:..."

The battery units should be connected to the same circuits that supply your "normal" egress lighting, so that when power drops out the battery units come on, and when the generator turns on the battery units turn off.

The battery units are an "emergency electrical system."

 

[gadfly56]

Your source of egress lighting seems a little unclear. Normally the egress pathway is lit by the standard building lighting. When the standby generator kicks on, the standard building lighting will continue as usual. In between, separate emergency exit way lighting provides the illumination for up to 90 minutes. I trust someone can find the "on" switch for the generator in that time if it doesn't kick on automatically. So, I'm not sure I understand your dilemma.

There are manufacturers who provide emergency ballast/battery packages to power standard fluorescent light fixtures so that strategically selected fixtures can perform as the required egress pathway lighting. See here for one of many possible solutions.

 

[texie]

The battery units should be connected to the same circuits that supply your "normal" egress lighting, so that when power drops out the battery units come on, and when the generator turns on the battery units turn off.

The battery units are an "emergency electrical system."

I would agree that the generator should supply the branch circuits that are powering the emergency light packs as a common sense and practical matter. That said, in my view this is an Art. 702 Optional Standby System and from a code standpoint the owner is free to power only what they deem necessary as it is not a required system in the first place.
I think, as the OP is proposing, an optional standby system combined with standalone emergency lighting makes a lot of sense for many types of occupancies as you can get more bang for your buck while adding a little redundancy and yet have much less code restrictions on the design of the electrical system.

 

[ceb58]

Just make sure it complies with 702.4(B)(2). Is there any cooking equipment in the building?

 

[mgookin]

Power off = em lights come on.
Generator kicks in = em lights go off and maintain a charge so that when your generator dies, you have em lighting during occupancy.

 

[steve66]

Should the battery units be powered by the generator, or no???

Yes, basically what David said - they should be on the generator with the other lights. THat is the only code compliant way to wire them to the same circuit that feeds the other lights (unless you have 3 or more circuits supplying the same area). And it also keeps the batteries charged during a long outtage.

That's the only way to go.