Keep battery operated bicycle lights to hand, front and rear with means of attaching them to your wheelchair.
Remember that an emergeny may require you to use your chair outdoors in the dark, perhaps in a power failure, being run down by an auto could be a real risk.

As others suggest, keep supplies at your work place including water, batteries, spare clothing, long life foods, flashlight, radio etc.

Would funds and storeage space permit of keeping a spare wheelchair at you work place? Just in case yours suffers any damage that cant be readily repaired.