How to Select Cloth-Covered Wire

Electrical Requirements

The first consideration is the electrical requirements of your application. If you have any doubts about what gauge you need or whether you need two- or three-conductor wire, you should consult an electrician. If you are installing the wire in your house (as opposed to on a lamp or appliance) you should always contact a building inspector to determine the laws in your state. Sundial personnel do not make recommendations on gauge or number of conductors due to liability issues. We encourage our customers to be very sure they use a reliable source to determine which type of wire to use. Please note that you can always use a 3-conductor wire where you only need two conductors by clipping the third conductor and leaving it unused. Please also note that the knob-and-tube style wire is intended for theatrical use only and its use as wiring for buildings does not meet modern building codes.

Wire Terminology and Styles

Conductors

A conductor is just another word for a wire. Two-conductor wire has two wires, either in parallel or twisted, one wire being used for the positive wire, one for the negative. Three-conductor wire has three wires, usually twisted, with the third wire being used as a ground. If you don’t know whether you need two- or three-conductor wire for your application, you should consult an electrician or building inspector.

Gauge

The second description of a wire is its gauge. The lower the number, the heavier the wire. For example, Sundial Wire’s knob-and-tube style wire is 12-gauge and is the heaviest wire in our line. 22-gauge is the smallest wire in our line. The gauge needed for a lamp or appliance is dependent on the draw of the bulb or motor and the length of the cord. The voltage and temperature ratings of the wires are listed on the web site and the price list. If you are in doubt about what gauge you need, you should contact an electrician. Sundial does not make recommendations on gauge due to liability issues.

Stranded or Solid Core

Another factor in the make-up of wire is whether the wire is stranded or solid core. Solid core wire is stiff and holds its shape when it is bent. Stranded wire is more flexible and does not hold its shape. Normal lamp cord is stranded. Right now, all of Sundial Wire’s wire is stranded except for the knob-and-tube style wire.

Style

In vintage-style, cloth-covered wire, there are several styles of multi-conductor wire: parallel or flat, twisted pair, twisted under one sheath or overbraid, and pulley cord. In parallel or flat wire, the conductors are laid side by side and covered in the cloth. In twisted pair wire each of the two conductors is covered in cloth braid and then the wires are twisted together. The final two styles have the wires twisted together first and then the twisted bunch is covered in one sheath or overbraid of cloth. In this style, the twist of the wire is evident beneath the braid. Pulley cord is similar to the overbraid style of wire but it is padded so that the cord is perfectly round, hiding the twist of the wire beneath the sheath.

Rayon or Cotton

Both cotton and silk were used early in the 20th century to cover wire. Today we use cotton and rayon. The cotton provides a matte (not shiny) covering, which is more appropriate on appliances and more down-to-earth lamps. Rayon, which like silk is shiny, is used for more elegant lamps, radios, phonographs, etc. This is the only real difference between the cotton and rayon covering: whether you want a matte or a shiny cloth covering.

Vintage-style wire can also be lacquered. Lacquer was used to keep the cloth from fraying at the ends. It was used mostly in utilitarian situations rather than when the wire was likely to be on display. For example, our knob-and-tube wire is lacquered and its function was to provide wiring throughout a house.