When operators must perform whole body access, it is crucial they are kept safe whilst inside the danger zone.
ISO 10218-2 section 5.6.3.4 'Manual reset, start/restart and unexpected start-up' states that ‘to ensure no one in the safeguarded space before start/reset, use the first practicable option from the following:”

“Give a clear an unobstructed view of the safeguarded space from the start / reset device”
In theory this sounds like a perfect solution, but in practice visibility can be very poor where obstacles and machinery operate, or where low level lighting can distort the view of safeguarded spaces.

“Use presence sensing devices to detect operators throughout the safeguarded space”
For small and simple areas presence sensing is a great option, but can quickly become costly and
impractical to guarantee detection in larger spaces with moving parts, blind spots and obstacles.