Live Wire (electricity) - Cables


Armoured cables with two rubber-insulated conductors in a flexible metal sheath were used as early as 1906, and were considered at the time a better method than open knob-and-tube wiring, although much more expensive.

The first polymer-insulated cables for building wiring were introduced in 1922. These were two or more solid copper electrical wires with rubber insulation, plus woven cotton cloth over each conductor for protection of the insulation, with an overall woven jacket, usually impregnated with tar as a protection from moisture. Waxed paper was used as a filler and separator.

Over time, rubber-insulated cables become brittle because of exposure to atmospheric oxygen, so they must be handled with care, and are usually replaced during renovations. When switches, outlets or light fixtures are replaced, the mere act of tightening connections may cause hardened insulation to flake off the conductors. Rubber insulation further inside the cable often is in better condition than the insulation exposed at connections, due to reduced exposure to oxygen.

Rubber insulation was hard to strip from bare copper, so copper was tinned, causing slightly more electrical resistance. Rubber insulation is no longer used for permanent wiring installations, but may still be used for replaceable temporary cables where flexibility is important, such as electrical extension cords.

About 1950, PVC insulation and jackets were introduced, especially for residential wiring. About the same time, single conductors with a thinner PVC insulation and a thin nylon jacket (e.g. US Type THN, THHN, etc.) became common.

The simplest form of cable has two insulated conductors twisted together to form a unit; such unjacketed cables with two or three conductors are used for low-voltage signal and control applications such as doorbell wiring. In North American practice, an overhead cable from a transformer on a power pole to a residential electrical service consists of three twisted (triplexed) wires, often with one being a bare wire made of copper (protective earth/ground) and the other two being insulated for the line voltage (hot/live wire and neutral wire). For additional safety, the ground wire may be formed into a stranded co-axial layer completely surrounding the phase conductors, so that the outmost conductor is grounded.

Read more about this topic:  Live Wire (electricity)

Other articles related to "cables, cable":

Live Wire (electricity) - Cables - Modern Wiring Materials
... Modern non-metallic sheathed cables, such as (US and Canadian) Type NMB and NMC, consist of two to four wires covered with thermoplastic insulation and ... It is often called Romex cable, since the first of its type was manufactured by Rome Cable Division of Cyprus Mines, Rome, New York ... the electrical building wire assets of General Cable in 2001 ...
Cable Management - Computer Data Cabling, Structured Cabling, LAN Cabling
... Generally, one end of a cable is terminated in the data cabinet ... The other end of a cable ends at the desk ... The cable management needs at either end are different ...
Letting The Cables Sleep - Track Listing
... UK CD 1 single "Letting the Cables Sleep (single version)" - 433 "Letting the Cables Sleep (Nightmares On Wax remix)" - 524 "Letting the Cables Sleep (original demo)" - 436 UK CD 2 single "Letting the Cables Sleep (si ...
Cable Management - Cable Labeling
... Color-coding of cables is sometimes used to keep track of which is which ... Documenting and labeling cable runs, tying related cables together by cable ties, cable lacing, rubber bands or other means, running them through cable guides, and clipping or ... drop ceilings, hooks or trays are used to organize cables and protect them from electrical interference Planning is especially crucial for cables such as Thicknet that do not bend around corners easily and fiber ...
Shaft Passer
... A similar, unnamed and also unattested, mechanism allows one cable to pass through another without breaking either ... The device works by using a spoked, rimless wheel that allows cables to pass through as it rotates ... The ends of the spokes are widened, and the cable is held together by a short curved sleeve through which these spoke ends slide ...

Famous quotes containing the word cables:

    It is not a piece of fine feminine Spitalfields silk—but is of the horrible texture of a fabric that should be woven of ships’ cables & hausers. A Polar wind blows through it, & birds of prey hover over it. Warn all gentle fastidious people from so much as peeping into the book—on risk of a lumbago & sciatics.
    Herman Melville (1819–1891)

    On the bare upland pasture there had spread
    O’ernight ‘twixt mullein stalks a wheel of thread
    And straining cables wet with silver dew.
    Robert Frost (1874–1963)