Original General Order 128

Section II

Definitions Of Terms As Used In These Rules

22.7    Practicable means capable of being accomplished by reasonably available, economic, and workable means.

A.    Clearances and depths required by these rules shall be deemed impracticable only to the extent that existing structures or natural obstructions require a reduction in such clearances or depths in the immediate vicinity of such obstruction; or in those exceptional cases where the clearance otherwise required would, in particular and limited circumstances, create a condition less safe than a reduction of such clearance.