Each elevator shall be equipped with at least 2 guide rails. Guide rails shall:

(1) Extend at least 6 in. beyond the maximum travel distance of the car with the buffers compressed.

(2) Be securely fastened to a vertical support for the full length of the elevator's travel.

(3) Be constructed of vertical grain fir or steel:

(a) If constructed with vertical grain fir, the rails shall be at least 1 1/2 in. x 1 1/2 in. and not vary in thickness by more than 3/16 in. on brake surfaces.

(b) If constructed of steel, it shall meet the requirements of subsections (4) and (5) of this section.

(4) Be able to resist a 250 lb. horizontal thrust.

(5) Be able to resist more than 1/2 in. total deflection when the car safety is applied.