Question: When may a cable become a risk? Would it be when an iPhone charger's ends are broken ? or ?

John Ging answered on 19 Nov 2014:

Depends on the type of cable. Any wire/cable exposed can be a risk. The current passing through it may short circuit to ground. Remember electricity will try to flow to a place of lower voltage/potential. Kinda like water always flows down to a lower place. If you touch that cable, the electricity will flow through you to ground (with less than ideal consequences).