When an Electrical Cord Is Plugged in and the Plug Gets Hot, Is That Dangerous?

Principles and Sources of Electricity

• The physical forces that drive a generator -- wind, steam, gas, diesel or water power -- convert torque into electrical energy. Chemical reactions are the source of battery power. Sunlight is converted into electrical energy through solar cells. This electrical energy is measured in voltage and current. The voltage is the potential difference between opposing poles, and the current, measured in amperes or amps, determines its capacity for work. Power sources are designed appropriate to their electrical load and power transmission lines.

Principles of Electrical Power Transmission

• Electrical power is generated at the power plant at a high voltage and current. Electrical power is transmitted through step-up transformers to high-tension, high-voltage wires across long distances, then to step-down transformers at a substation. This substation further steps down the power, in voltage, current and phase appropriate to industrial, commercial and residential uses. Most residential service delivers 120 or 220 volts of alternating current between 50 and 200 amps at the electrical meter and fuse or breaker box.

Wiring Principles

• All wiring is designed within limits imposed by local electrical code. These limits are imposed for reasons of planning and safety, and are given as a relationship between voltage, current, wire material, distances and wire gauge. For example, a circuit with a 20 amp 120 volt rating may be designed for 10 gauge solid copper wiring matched to a 20 amp circuit breaker. The principle is that the largest current and voltage is at the source of power and divided or branched off into smaller circuits to the point of use at the outlet or appliance, with switches, fuses or breakers in between.

Overloading

• Hitting the designed limit of your electrical system may begin when all outlets are filled, when the current draw meets or exceeds the designed limit, or when several appliances on one circuit are used at once. Electrical wiring is designed to work within limits to control against thermal failure. Electrical wiring generates known quantities of heat due to electrical resistance inherent to the wiring or connections. This heat may concentrate at points of use within conduits or electrical plugs. Accumulated heat has several dangerous outcomes. Heat may melt or deteriorate insulating materials, creating a fire hazard. In addition to the fire hazard, insulation material that has melted away from the conductors may create a shock hazard in addition to creating conditions ripe for a short circuit.