Cords

      

CORDS:
Wiring that is not used for house circuits is called cords. They're either round, jacketed, or flat. They're designed to be flexible. Jacketed cords have stranded copper conductors (two or three); thermoplastic insulation; fillers, usually jute; a separator for the conductors; and a thermoplastic jacket.

Most cords have fine stranded wire conductors, and the insulated wires are colored differently from cable for easy identification. Modern three-wire European cord has two wires colored brown for live and blue for neutral, plus a green/yellow striped wire. Two-wire cord has no ground. The wires are either colored brown and blue, or uncolored. Old three-wire has a red hot wire and a black neutral wire (the same as cable), plus a plain green ground wire. Cord that is old enough to have this coloring should be carefully checked to make sure it has not deteriorated. U.S. cord has colored conductors: black for hot, white for neutral, and green for ground.

Sizes of cords range from No. 18 to No. 10 and even larger. National Electric Code ratings for these cords are: No. 18-7 amps; No. 16-10 amps; No. 14-15 amps; No. 12-20 amps; and No. 10-25 amps.

Many cords are highly specialized. The most familiar of all cords is Underwriters Type SP or SPT. Nicknamed "zip" cord, it's the two-wire material that most small appliances are fitted with. The two halves can be zipped apart when malting connections. Most common size is No. 18, but heavier gauges are available. A three-wire version also is made. Type SP has rubber covering. Type SPT has plastic insulation. The data is sometimes on the cord.

Another popular cord is Type S, which is round and insulated with rubber. Type ST is the same, but is plastic insulated. Each conductor is insulated too. Types S and ST are for use where the cord will receive abrasion, such as a vacuum cleaner cord. Another type, SJ, has a thinner outer covering than Type S and is generally more useful around the house for washing machines, refrigerators, small motors and the like. The J means junior. Oil-resistant cord of this kind is designated Type SEO for Type S and SJEO for Type SJ. These are made with neoprene covering.

Cord used for appliances that generate heat, such as irons and heaters, is simply called heater cord. Type HPD is the Underwriter's designation. The outside of HPD heater cord is a woven covering of cotton or rayon. Inside, a layer of asbestos wool and neoprene covers each wire. HPN heater cord is a "zip" cord type with neoprene covering.

When replacing an appliance cord, be sure to get the same type of cord that originally came with the appliance. You should stick to the same length, too. This avoids having too much resistance from an overly long appliance cord. Don't overload a cord by using one that's too small for the job. For additional properties - abrasion resistance, oil resistance, etc. - cords with rubber, neoprene and tougher plastic coverings are available.

Splicing of electrical cords is only a temporary repair. When necessary, it can be done as follows.

1. Cut away the damaged portion of the insulation with a knife or scissors. Cut both wires in half with wire cutters.
2. Remove about 1' of insulation from each wire with a wire stripper. Then twist the ends of both wires together.
3. Wrap each wire with electrical tape. Overlap the tape onto the remainder of the cord.

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