BU2: Insulators and Conductors

Electrical Conductors

substances that allow the flow of electric current

Bare Conductor

conductor having no covering insulation

Insulated Conductor

encased within a material of composition and thickness recognized by code

Covered Conductor

encased within a material of composition and thickness not recognized by code

Aluminum, Brass, Copper, Lead, Iron, Tin, Zinc, Silver, Nickel, Platinum

Examples of good conductors

Insulator

material or substance that does not permit electric current to pass or flow easily

Class A Insulation

consists of (1) cotton, silk, paper and materials of paper composition impregnated or immersed in an insulating liquid; (2) molded or laminated materials with cellulose filler, phenolic resin (3) sheets of cellulose acetate / similar cellulose products (4) varnishes or enamel applied to conductors

Class B Insulation

consists of mica, asbestos or fiberglass, all with binder

Class C Insulation

consists entirely of mica, porcelain, glass, quartz or similar materials

Class O Insulation

consists of cotton, silk, paper or similar materials that are not impregnated or immersed in an insulating liquid

Conductor Insulation

1. Moisture and heat resistant rubber
2. Heat resistant rubber
3. Silicon rubber
4. Thermoplastic
5. Thermoplastic and asbestos
6. Flame resistant, moisture and heat resistant thermoplastic
7. Moisture resistant
8. Perfluoroalkoxy

Insulating Materials

1. rubber
2. porcelain
3. varnish
4. slate
5. glass
6. mica
7. latex
8. asbestos
9. thermoplastic
10. oil
11. wax
12. dry air
13. paper
14. silk
15. wood

Drawing

method of producing wire; characterized by having metal drawn into series of holes on a drawplate or die of varying diameters, from larger to smaller holes

Ichabod Crane

introduced drawing of wire as a manufacturing process by using waterwheel to provide mechanical power

Wires

electrical conductors which are 8mm^2 (No. 8 AWG) or smaller

Wires

single conductor number 14 AWG, 12 AWG, 10 AWG, and 8 AWG

AWG (American Wire Gauge)

preceded by a number which indicates the size of the wire; numbers is used in reverse order

Stranded Wire

group of wires twisted to form metallic string

Circular Mil Area

= circular mil area of each strand x total number of strands

Cord

term given to an insulated wire that is flexible

Cables

electrical conductors larger than wires; a single number 6 AWG to 0000 AWG; two or more wires assembled in a single jacket

Bus, Busbar

rigid, electric conductor, usually metal bar, hollow tube or rod which form a connection between electric circuits

Circular Mil (CM)

unit of cross section in the AWG

mil

means one-thousandth of an inch (0.001 in); area of a circular wire having a diameter of 1 mil

Square Mil

area of a square having its side equal to 1 mil

Copper

ductile, malleable, excellent conductor of heat and electricity; harder than zinc, softer than iron; 50% of its total output is used for manufacturing electrical apparatus and conductors

Aluminum

produced by the formation of many metals such as feldspar, mica, alum, cryolite, clay bauxite and several forms of aluminum oxide (alumina); it is tough, fairly high strength and lightweight; lighter in weight than copper conductors; cost less than copper conductors; has approximately 80% of the conductivity of copper conductors; can create electrical problems if installed improperly