I'm not sure what clause you are speaking of. Normally it means that if a hazardous condition could exist the operation must remain under continuous supervision so that an accident should not occur, protection of a danger zone. You may be require to lock out a control panel if not under continuous supervision if another person could accidentally create a hazardous motion. An example is a pluggable device, the plug acts as the disconnect device. When the plug is disconnected it must be within site of the operator/maintenance/service person at all times (continuos supervision) so that no one will plug it in without his/her knowledge. Christopher Caserta
ccaserta@us.tuv.com
Ph:904-225-0360