The device may be used to test {HEAD ~ such switches} without affecting {TAIL ~ the load} controlled by the switch 
without affecting
The device may be used to test { HEAD ~ such switches } without affecting { TAIL ~ the load } controlled by the switch
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH