61 Pa. Code § 871.7 – Time, place and manner of conducting drawing.

(a) Time of drawing. A Powerball drawing will be held twice a week or as publicly announced by the Secretary.
(b) Place of drawing. A Powerball drawing will be conducted in a location selected by the MUSL in West Des Moines, Iowa, or other location selected by the MUSL for promotional or other reasons.
(c) Manner of conducting drawings. The MUSL will draw at random five numbers from a set of balls numbered 1 through 49 and one Powerball number from a set of balls numbered 1 through 42 with the aid of mechanical drawing equipment. All drawings will be observed by security personnel and independent auditors and the validity of a drawing will be solely determined by the MUSL.

This section cited in 61 Pa. Code § 871.22 (relating to changes to Powerball).