crwdns2934241:0crwdne2934241:0 DrGlowire

crwdns2934249:0crwdne2934249:0:

You were right the first time, it is a symbol for shield on a cable of wires.  In the larger picture there are a couple of wires with the loop and the loop connects to a common point between the other two wires.  If you open the cover and trace the wires you will probably see that the 2 or more are in a shield and the shield connects to ground.

crwdns2915684:0crwdne2915684:0:

open