(2)(a)Two independent and efficient means shall be provided and maintained for interchanging separate, distinct and definite signals between the top of the shaft and-(i)the bottom or other permanent landing of the shaft; and(ii)every inset for the time being in use, and one of such system shall be by electrical means.(b)There shall also be provided and maintained efficient means for transmitting signals from the top of the shaft to the winding engineman and all signals shall be transmitted by mechanical or electrical means;
