230. The switches prescribed by paragraphs 2 and 3 of section 229 shall activate an exhaust throttle governor which shall immobilize the hoist before the conveyance, counterweight or rope attachments reach the sheave or any other obstacle in the shaft or headframe.
Notwithstanding the foregoing, during shaft sinking working, the lower limit of travel shall be adjusted to allow the conveyance to reach the bottom of the shaft but the length of cable that can be unwound after the conveyance has reached the bottom of the shaft shall be less than twice the circumference of the drum of the hoist.