N.Y. Comp. Codes R. & Regs. tit. 12 § 23-1.15 : DEPARTMENT OF LABOR — Industrial Board Of Appeals — The Industrial Code — Protection In Construction, Demolition And Excavation Operations —1 - General Provisions —1.15 - Safety railing

Whenever required by this Part (rule), a safety railing shall consist as a minimum of an assembly constructed as follows:

(a) A two inch by four inch horizontal wooden hand rail, not less than 36 inches nor more than 42 inches above the walking level, securely supported by two inch by four inch vertical posts at intervals of not more than eight feet.
(b) A one inch by four inch horizontal midrail.
(c) A one inch by four inch toeboard except when such safety railing is installed at grade or ground level or is not adjacent to any opening, pit or other area which may be occupied by any person.
(d) The hand rail of every safety railing shall be smooth and free from splinters and protruding nails.
(e) Other material or construction may be used for safety railings required by this Part (rule) provided such assemblies have equivalent strength and assure equivalent safety.

N.Y. Comp. Codes R. & Regs. Tit. 12 § 23-1.15