Where the health and safety of persons may be endangered by a fault in the operation of unsupervised machinery or a related product, the machinery or related product shall be equipped in such a way as to give an appropriate acoustic or light signal as a warning.
Where machinery or a related product is equipped with warning devices, these shall be unambiguous and easily perceived. The operator shall have facilities to check the operation of such warning devices at all times.
The requirements of the specific Union legal acts concerning colours and safety signals shall be complied with.