SHORT CIRCUIT  BURNED/FRAYED WIRING

G.  SHORT CIRCUIT  BURNED/FRAYED WIRING:
Shorting or short-circuiting means that the electrical current has found an unintended path to ground and draws an uncontrolled amount of current through the wires.  Usually, the circuit protective device will trip or blow and the current will stop.  Huge overloads of current flowing through a short circuiting wire will overheat the wire almost instantly.  Often it melts the insulation and causes a fire.  If a fire does not occur, the likelihood of having another short circuit is very high due to the melted insulation.

If the insulated conductors within a wire package touch, another short circuit will result.  Overheating or age can make insulation around a wire brittle.  Pieces can break loose (Fig. G1, Item A) and expose the wire (Fig. G1, Item B).  When receptacles with such wiring are removed and resecured, the wires may drop insulation and then short circuit when they are pressed back into the outlet box.  Generally, fuses and circuit breakers will prevent this, but some short circuits can maintain small arcs and produce enough heat to cause fires without blowing fuses or tripping circuit breakers.

Fig. G1

NOTE: A blackened fuse indicates that there was a short circuit while a broken filament indicates an overload.

WHAT TO:  HOW TO:
Never ignore a short circuit.  It is indication that something is wrong.  It is dangerous and must be corrected.  Find the cause before reactivating the circuit. Amateurs BEWARE: A professional electrician should be called to make repairs.

BURNED/FRAYED WIRING:
Burned circuit ends at fuses or circuit breakers (Fig. G2, Item A) indicate a loose connection or that the circuit has overheated. The insulation at the wire’s end will melt slightly and may even show signs of charring (Fig. G2, Detail B).  A tight circuit that is burned may have already been repaired.  OBVIOUSLY THIS IS A WARNING! Check the breaker to make sure the capacity is matched to the correct wire size.

Fig. G2

Frayed wiring sometimes occurs when a wire is attached to a machine that vibrates.  This frequently occurs on disposals and dryers.  Occasionally, a romex wire gets pulled through a tight hole in a stud or a panel and has its insulation stripped, setting up a short circuit.

WHAT TO:  HOW TO:

The burned wiring portion should be cut away, and a new clean connection established.  Have a professional electrician check the circuit to determine whether an overloading condition exists.  Checks of such circuits can be difficult since the leakage to ground may be INTERMITTENT.  Frayed wiring should be replaced.

REFERENCE: E1, E2, E4, E5, E17