Except as provided in subsection (b) of this section and in section
1675 of this title, the maximum part of the aggregate disposable earnings of an individual for any workweek which is subjected to garnishment may not exceed
(2)
the amount by which his disposable earnings for that week exceed thirty times the Federal minimum hourly wage prescribed by section
206
(a)(1) of title
29 in effect at the time the earnings are payable,
whichever is less. In the case of earnings for any pay period other than a week, the Secretary of Labor shall by regulation prescribe a multiple of the Federal minimum hourly wage equivalent in effect to that set forth in paragraph (2).