a) Those which need to be opened for normal operation (removable covers, doors). These shall not require tools for their opening or removal. They shall be provided with locking facilities unless the safety of persons is assured by a suitable interlocking device.
b) All other covers, doors or roof. They shall be provided with locking facilities or it shall not be possible to open or remove them before doors used for normal operation have been opened. They shall require tools for their opening or removal.