How bright should I illuminate my job site?

Here is a guidance chart from OSHA 1926.56 Standard that provides illumination guidance in Foot candles (FC).

1926.56(a)

General. Construction areas, ramps, runways, corridors, offices, shops, and storage areas shall be lighted to not less than the minimum illumination intensities listed in Table D-3 while any work is in progress:

    TABLE D-3 - MINIMUM ILLUMINATION INTENSITIES IN FOOT-CANDLES

____________________________________________________________________
|
Foot-Candles | Area of Operation
______________|____________________________________________________
|
5.............| General construction area lighting.
3.............| General construction areas, concrete placement,
| excavation and waste areas, access ways, active
| storage areas, loading platforms, refueling, and
| field maintenance areas.
5.............| Indoors: warehouses, corridors, hallways, and
| exitways.
5.............| Tunnels, shafts, and general underground work areas:
| (Exception: minimum of 10 foot-candles is required
| at tunnel and shaft heading during drilling,
| mucking, and scaling. Bureau of Mines approved cap
| lights shall be acceptable for use in the tunnel
| heading)
10............| General construction plant and shops (e.g., batch
| plants, screening plants, mechanical and
| electrical equipment rooms, carpenter shops,
| rigging lofts and active store rooms, mess halls,
| and indoor toilets and workrooms.)
30............| First aid stations, infirmaries, and offices.
______________|____________________________________________________

 
1926.56(b)
Other areas. For areas or operations not covered above, refer to the American National Standard A11.1-1965, R1970, Practice for Industrial Lighting, for recommended values of illumination.