The switching circuits are chosen such that defects causing the electrical switching circuit to short circuit do not affect the electromechanical switching circuit and defects causing {HEAD ~ the electromechanical switching circuit} to {TAIL ~ short circuit} do not affect the electrical switching circuit 
to
The switching circuits are chosen such that defects causing the electrical switching circuit to short circuit do not affect the electromechanical switching circuit and defects causing { HEAD ~ the electromechanical switching circuit } to { TAIL ~ short circuit } do not affect the electrical switching circuit
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH