Or. Admin. R. 437-002-0145
Warning Devices. Warning signs, danger signs, warning flags, warning lights, or similar devices shall be conspicuously posted at all locations where existing conditions not otherwise adequately guarded warrant their use.
ORS 654.025(2) & 656.726(3)
ORS 654.001 - 654.295
OSHA 6-1994, f. & cert. ef. 9-30-94