Electrical Wire Types

I don't know if I like the wiry type

The lesson of aluminum

The importance of using proper electrical wire and cable types is best learned from a discussion of the adoption of aluminum electrical wire in the 1970s. Aluminum wire, over time, became implicated in numerous house fires. Most municipal codes no longer allow the use of aluminum wire for new construction. If for some reason your local code does not limit its use, I would still recommend that you avoid the use of any aluminum electrical wire.

Having said that, if your home was built in the 70s and has aluminum wire, there is no need to panic. The real lesson of this is that aluminum is fine if properly installed. Keep in mind that it is less forgiving than copper wire if it is improperly installed. Aluminum has a number of issues that make it dangerous in the hands of those who are not qualified in proper installation.

Household electrical wire

Electrical wire types

NM Cable is the designation for cable used to carry power in most homes. NM cable is suitable for use in dry, protected areas (i.e. inside stud walls and on the sides of joists), which are not subject to mechanical damage or excessive heat. Most new homes are wired almost exclusively with NM wire. There are several different electrical wire types that fall under the blanket term of NM cable, the most common of which are as follows.

BX cable: technically known as armored cable or "AC," has a flexible aluminum or steel sheath over the conductors and is fairly resistant to damage.

TECK cable: is AC with an additional external thermoplastic sheath.

Electrical wire sizes

Wire size is measured in gauges. The most common electrical wire is 12-2 gauge nmb. Of largest concern when considering electrical wire sizing is its ampacity. The ampacity of electrical wire is its maximum rated current. The criteria used to determine a wire's ampacity is quite complicated and considers such characteristics as insulation coating and the physical characteristics of the metal itself.

Gauge is expressed inversely. For example, a wire that is measured as 12 gauge is larger than one that is 14 gauge. Diameter approximately doubles once for every six gauge sizes that are advanced. It is commonly accepted that a change of three gauge sizes will either double or halve the ampacity, depending on which way the gauge size changes.

More information on electrical wire