American Journal of Science and Arts

The telegraph was not only important for communication within the armed forces, but also in the civilian sector, helping political leaders to maintain control over their districts. A spokesman for LV told us: 'If someone was to trip or fall over a charging cable and our customer was found legally responsible or negligent our policy would cover it under "liability to other people". A cable should only be placed over the footway when the vehicle is charging and should always be removed when not in use. Portable appliances with metal cases also have a bonding conductor in the flexible cable and plug connecting them to the distribution system. An outlet is defined by the NEC as "a point in the wiring system at which current is taken to utilization equipment". Ground-fault circuit interrupter (GFCI) protection is required on receptacles in wet locations and locations where there exists an easy path for fault current to travel to earth. Ground is a safety conductor with a low impedance path to earth. Neutral wire is the return conductor of a circuit; in building wiring systems, the neutral wire is connected to earth ground at only one point.

Leg as in "hot leg" refers to one of multiple hot conductors in an electrical system. The most common three-phase system will have three hot legs, what are electric cables 208 V to each other and 120 V each to the neutral. The most common residential and small commercial service in Canada and the U.S., single split-phase, 240 V, features a neutral and two hot legs, 240 V to each other, and 120 V each to the neutral. The circuit return conductor (neutral) is also connected to ground at the service entrance panel only; no other connections from neutral to ground are allowed, unlike regulations in some other parts of the world. Two-wire outlets having no grounding conductor may be protected by a GFCI or one upstream of the receptacle and must be labelled "No Equipment Ground" and "GFCI Protected". It is often called the "ground wire," or safety ground. At the sending station, an operator taps on a switch called a telegraph key, spelling out text messages in Morse code. The Morse operator distinguished a dot and a dash by the short or long interval between the two clicks.

It is not intended to provide overload protection, but instead protects a cable that is exposed to a short circuit. Circuits with larger currents (such as for electric furnaces, water heaters, air conditioners, or sub-mains to additional circuit panels) will have larger conductors. Furnaces, electric water heaters, heat pumps, central air conditioning units, electric dryers, electric stoves or cooktops, and built-in microwave ovens must be on dedicated circuits. The foregoing is just a brief overview and must not be used as a substitute for the actual National Electrical Code. For electrical wiring in Canada, the Canadian Electrical Code is a very similar standard published in Canada by the Canadian Standards Association. South African Bureau of Standards (2006). Plug and socket-outlet systems for household and similar purposes for use in South Africa Part 0: General and safety requirements (PDF). North American standards state that the neutral is neither switched nor fused except in very narrowly defined circumstances. The work will be inspected by a designated authority at several stages before permission is obtained to energize the wiring from the local electric utility; the inspector may be an employee of the state or city, or an employee of an electrical supply utility.

All wiring in a circuit except for the leads that are part of a device or fixture must be of the required gauge or larger. BS 546:1934 clause 2 specifies interchangeability with BS 372 Part II which includes the same four plug and socket sizes. An AFCI device is designed to trip quickly when it detects potentially dangerous arcing that could start a fire, but not trip with harmless arcing as part of the normal operation of devices such as motors. The code provides rules for sizing electrical boxes for the number of wires and wiring devices in the box. Grounding (earthing) of distribution circuits is a notable difference in practice between wiring systems of the United States and those of other regions. Most circuits have the metallic components interconnected with a grounding wire connected to the third, round prong of a plug, and to metal boxes and appliance chassis. All metallic systems in a building are to be bonded to the building grounding system, such as water, natural gas, HVAC piping, and others. If these wires are not insulated, this would constitute a violation of the National Electrical Safety Code. It is sponsored by the National Fire Protection Association (NFPA) and has been periodically revised since 1897. Local jurisdictions usually adopt the NEC or another published code and then distribute documents describing how local codes vary from the published codes.