From the guide:
“Many lighting control applications require support for emergency lighting of some type. These emergency lighting circuits typically provide minimum illumination levels for egress and safety as required by NFPA 101 Life Safety Code or other local building codes and standards. Designers may meet these requirements with dedicated emergency lighting fixtures. These fixtures would be fed directly from emergency branch circuits or from internal power sources (rechargeable battery packs are typical) when grid power has failed. A disadvantage to these approaches is that these dedicated luminaires often go largely unused as they provide lighting only when normal power has failed. An alternative is to utilize the same fixtures for both normal and emergency lighting needs. Greengate lighting control panels for energy management from Cooper Controls have been designed to accommodate this approach.”
Check out the complete guide here.