Section 21.38. Trestle and extension trestle ladders

(a) It is recommended that trestle ladders over 20 feet in length not be used.

(b) Extension or base sections of extension trestle ladders over 20 feet in length shall not be used.

(c) The dimensions of side rails of trestle ladders or of the bases of extension trestle ladders shall not be less than the following:

Length of Side Rails (feet)	Thickness (inches)	Depth (inches)
Up to and including 12	1 5/16	2 1/2
Over 12, up to and including 16	1 5/16	2 3/4
Over 16, up to and including 20	1 5/16	3 1/4

(d) The extension section shall have parallel rails. The dimensions of side rails shall not be less than the following:

Length of Side Rails (feet)	Thickness (inches)	Depth (inches)
Up to and including 12	1 5/16	2 1/2
Over 12, up to and including 20	1 5/16	2 3/4

(e) Trestle ladders and base sections of extension trestle ladders shall be so spread that the width of the trestle at the bottom, inside to inside, is equal to or greater than 5 1/2 inches per foot of length of ladder.

(f) The minimum distance between side rails of trestle ladders and the extension sections of trestle ladders shall be not less than 12 inches. The spread of the side rails for trestle and base of extension trestle ladders may not be less than one inch per foot of length of ladder.

(g) Bearings shall be equivalent in strength, wear, and construction to the specifications of § 21.33 (relating to steps). Bearings may not exceed 18 inches on centers.

(h) The top of side rails of trestle and base sections of extension trestle ladders shall be cut on bevel, or other means shall be provided to prevent them from spreading. In addition a locking device or spreader to hold the front and back sections in an open position shall be a component of each ladder.

(i) The locking device for securing the extension to the base shall be of an approved design.