A nonconforming use may be expanded, extended or enlarged within the boundaries of the zoning lot on which it is located by 33 1/3% of base floor area, as defined, lot coverage or building volume if required to accommodate an increase in trade, business or industry. Such an expansion, extension or enlargement in floor area, lot coverage or building volume of more than 33 1/3% and up to 50% can be effected only upon the grant of such a special exception by the Zoning Hearing Board. Expansion, extension, or enlargement greater than 50% of base floor area, lot coverage or building volume, is prohibited. Any such expansion, extension or enlargement shall comply with all other applicable provisions of this chapter.