Beacons & sounders: it's a matter of 'good practice'

Visible and audible warning lights on a machine or workstation generally indicate a change in status and may also warn of an error in machine operation or a malfunction. In any event, staff working in the vicinity of equipment displaying warning lights need to be aware of the change in machine status indicated by them, and take such steps as their operating procedures require.

So, how can a supplier of visible and audible warning systems contribute towards ensuring that ‘good practice’ is achieved in the workplace? A starting point is the risk assessment; once the risks have been identified, the next stage is to reduce them to an acceptable level. The general rules are: if there’s a risk, eliminate it; if you can’t eliminate it, guard it, and if you can’t guard it, warn about it.

One of the most dangerous phases of any machine operation is start-up. When you press the ‘go’ button, the last thing you want it to do is to start the machine. It must first initiate a procedure to check for safety Interlocks and self-test routines to ensure it is in an appropriate mode for start-up, with guards closed and so on. It might be common practice to monitor danger zones with light curtains and similar technology, but these systems can be overridden by operators; unless you can see the danger zone is clear, can you be sure it is safe to start?

The Directive tells us that "machinery must not start up unexpectedly". It’s difficult to define what "unexpectedly" means in this context, so let’s turn it around, making sure that anyone in the vicinity of a machine will expect an audible and/or visual warning as part of its start-up sequence.

Now we’re all familiar with the concept of traffic lights and will intuitively understand that a red light is something that requires a certain defined response. So it is with visible and audible warning systems. The characteristics of the signal, the brightness of the beacon and loudness of the sounder need to be appropriate to the machine and its environment. And, just as importantly, make sure the paperwork’s done and the meaning of the signals is included in the operating manuals.