We have a range of machines where various slow moving part are protected by interlock switches. We are implementing a regime to record the checks rather that the ad-hoc (it worked when we last went inside) scenario that exists at present. What frequency would be appropriate to carry out this checklist. I don't want it so frequent that it does not get done because it takes too much time but I don't want it so infrequent that something could go wrong. It's all new kit with no history of failure

Its many years since I was involved in manufacturing. But at that time all interlocks were checked at the start of each shift and when any tool change had taken place. This very much reflected what was required by the Power Press Regulations in force at that time and which we also applied to injection moulding machines, guillotines and similar equipment which employed interlocked guards.

Thanks for your replies. I have already sent the engineers running towards the supplier information - suppliers of the machines and the switches. You have confirmed my thoughts that there is no defined frequency, that would have to depend on the degree of hazard within, the need to access it and the amount of use that it gets. The phone support at the British Safety Council have come up with similar views. I feel a risk assessment coming on....