Back to Primary Wire

Electrical Wire Size Chart

Primary wire is used for most automotive wiring applications including wiring of sensors, relays, fuse blocks, and lighting. It is highly resistant to grease, oil and acids making it ideal for these general mechanic applications. Generally designed with a resistant PVC coating, this copper wire can also be used for power and ground wiring.

It is important to use the appropriate size wire for the circuit you are running. The more current being driven in the circuit, the larger the wire you will need. Here are some typical applications by gauge size:

Typical Applications

20 ga. – 16 ga.
Signal wiring for vehicle controllers like sensors, injectors, and sending units.

16 ga. – 14 ga.
Most common sizes running lighting, radios, relays, switches, switch panels, control panels.

12 ga. – 10 ga.
Typically used more for power wires, grounds, relays, trailer sockets, motors, higher amperage circuits.

8 ga.
Component power and grounds, high amp circuits.

Gauge Size

Gauge is determined by the number of copper strands and micrometer measurement of the individual strands found within the PVC insulation of each primary wire. Combined, these two numbers give us a conductor stranding.

Gauge = Conductor Stranding
20 Gauge = 7 / 0.0126
(7 strands measuring 0.0126 each)
18 Gauge = 16 / 0.0100
16 Gauge = 19 / 0.0112
14 Gauge = 19 / 0.0140
12 Gauge = 19 / 0.0177
10 Gauge = 19 / 0.0223
8 Gauge = 19 / 0.0281

Wire at Del City

Del City stocks a single conductor copper wire with PVC (polyvinyl chloride) insulation for added strength and protection. The insulation protects the copper wire in high heat or extreme cold, allowing it to run optimally between temperatures of -40°C to 105°C, or -40°F to 221°F. The smooth surface PVC is ideal for constructing wire harnesses and is easy to pull through loom or conduit. UL rated primary wire is also available, found under RVI Wire.

You will find a full stock of Primary Wire available in a variety of spool sizes, colors and gauge sizes.

Gauge sizes:
Range from 8 - 20 gauge

Include red, white, blue, green, black, yellow, and brown. Select gauge sizes also include gray, purple, orange, pink, tan, light blue, and light green.

Spool sizes:
Range from 100' - 6,000'
Thrifty spools are also available in a variety of gauges and colors. These are short length spools, ranging 10 - 45', ideal for small jobs or resale.