Diode protection 512, e.g., crossed diodes connected in {TAIL ~ parallel} with one another and with {HEAD ~ a resistor element} may be connected across pairs of conductors in each circuit 
Diode protection 512 , e.g. , crossed diodes connected in { TAIL ~ parallel } with one another and with { HEAD ~ a resistor element } may be connected across pairs of conductors in each circuit
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH