To facilitate access to the telescope, the dome is provided with a rising floor. Control of this is achieved through a control panel (yellow) which although on a 4 metre extension lead is normally left hanging on a post below the dome rotation control panel. Four buttons give fast raise and lower (the upper - i.e. near cable input - two buttons ) and slow raise and lower (bottom 2 buttons ). The floor control has 2 circuit breakers, 1 power switch and for safety reasons, 3 micro switches and 3 emergency stop buttons ( apart from the upper and lower level limit switches) which can disable the floor operation. The procedure for investigating rising-floor malfunctions is explained in Section 2.3 below.
Of the 3 micro switches by far the most troublesome is that on the gate giving access to the observing floor. The gate must be fully closed in order for the floor to be operative. At present the vibration of moving the floor is sufficient to 'open' the gate and the floor will stop for no apparent reason. The other micro switches, which are less likely to be of concern, detect whether the rising floor hatches are open and whether the ladder of the rising floor is in place.
Three emergency stop buttons are also provided one by the gate, one on the floor control paddle, and one near the under floor access next to the control room door. These can be depressed accidentally. If the floor fails, check these stops are fully out - particularly the one by the gate.