Selecting a Marker Size for Wire Marking

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Wire Markers

An effective wire marking system can boost efficiency and safety in the workplace. Standardized labels help workers identify cables quickly and easily, which cuts down on the time needed to complete a task. Incidents can also be avoided when workers have the assurance they are handling the correct wires.

Choosing the best way to mark wires can be overwhelming, especially to those who are new to the process. Luckily, understanding a few common abbreviations that are used in wire marking and which factors will weigh heavily into your decision can go a long way in helping you select the best markers for your project.

Considerations for Choosing a Wire Marker

To choose the ideal wire marker for the application you need, it helps to consider certain factors, including:

  • Environmental conditions. If your wires are in contact with chemicals, water, or dirt, you need durable labels made from material that will withstand these elements. This saves you from wasting time and money to continually replace faded wire markings.
  • Marker material. There are a variety of material options for wire markers, including vinyl, nylon, and teflon. Vinyl wire markers are resistant to oil and dirt, while nylon and teflon are better suited for wires in extreme temperatures or around corrosive chemicals.
  • Type of wire marker. You have several options for this factor, as well—from wrap-around markers, to sleeves (also known as shrink tubing), to tags. Your choice will depend on how much information you need to fit on the label and if it is temporary or permanent marking. If there is more than one wire, you can bundle them together and label the bundle with a tag that is attached by cable tie.

Gauge Size and Diameter

Wire gauges are used to measure the diameter of round, electrically conducting wires. Whether you use sleeves or wrap-around markers, the size of the gauge on the wire you are attempting to mark will play an important role in ensuring that your label fits correctly. There are several wire gauge standards; the International Electrotechnical Commission (IEC) 60228 is the international standard for insulated cables. The most commonly used one in the United Staes is the AWG, the American Wire Gauge.

If you know the gauge size of your wire, you can calculate the size needed for your label to properly cover the wire. As a general rule of thumb, the length of the label is about five times the size of the wire’s outer diameter. The following charts are helpful references:

Type THW Wire O.D.

Size
AWG.
O.D.
mm (inch)
Circumference
mm (inch)
Minimum Recommended Label Height
mm (inch)
18 2.74 (0.108) 8.64 (0.34) 12.70 (0.500)
16 3.00 (0.118) 9.42 (0.37) 12.70 (0.500)
14 4.11 (0.162) 12.91 (0.51) 19.05 (0.750)
12 4.55 (0.179) 14.29 (0.56) 25.40 (1.000)
10 5.05 (0.199) 15.86 (0.63) 25.40 (1.000)
8 7.01 (0.276) 22.01 (0.87) 38.10 (1.500)
6 8.20 (0.323) 25.75 (1.02) 38.10 (1.500)
4 9.45 (0.372) 29.67 (1.17) 44.45 (1.750)
3 10.19 (0.401) 32.00 (1.26) 50.80 (2.000)
2 11.00 (0.433) 34.54 (1.36) 50.80 (2.000)
1 12.90 (0.508) 40.51 (1.60) 63.50 (2.500)
1/0 13.95 (0.549) 43.80 (1.72) 63.50 (2.500)
2/0 15.11 (0.595) 47.45 (1.87) 76.20 (3.000)
3/0 16.43 (0.647) 51.59 (2.03) 76.20 (3.000)
4/0 17.91 (0.705) 56.24 (2.21) 88.90 (3.500)

Type THHN Wire O.D.

Size
AWG.
O.D.
mm (inch)
Circumference
mm (inch)
Minimum Recommended Label Height
mm (inch)
18 2.26 (0.089) 7.10 (0.28) 12.70 (0.500)
16 2.54 (0.100) 7.98 (0.31) 12.70 (0.500)
14 2.67 (0.105) 8.38 (0.33) 12.70 (0.500)
12 3.10 (0.122) 9.73 (0.38) 12.70 (0.500)
10 3.89 (0.153) 12.21 (0.48) 19.05 (0.750)
8 5.54 (0.218) 17.40 (0.68) 25.40 (1.000)
6 6.53 (0.257) 20.50 (0.81) 31.75 (1.250)
4 8.33 (0.328) 26.16 (1.03) 38.10 (1.500)
3 9.04 (0.356) 28.39 (1.12) 44.45 (1.750)
2 9.86 (0.388) 30.96 (1.22) 50.80 (2.000)
1 11.43 (0.450) 35.89 (1.41) 57.15 (2.250)
1/0 12.47 (0.491) 36.16 (1.54) 63.50 (2.500)
2/0 13.64 (0.537) 42.83 (1.69) 63.50 (2.500)
3/0 14.94 (0.588) 46.91 (1.85) 69.85 (2.750)
4/0 16.41 (0.646) 51.53 (2.03) 76.20 (3.000)

Type PVC Wire O.D.

Size
AWG.
O.D.
mm (inch)
Circumference
mm (inch)
Minimum Recommended Label Height
mm (inch)
22 1.57 (0.062) 4.93 (0.19) 7.62 (0.300)
20 1.75 (0.069) 5.50 (0.22) 7.62 (0.300)
18 2.00 (0.079) 6.28 (0.25) 12.70 (0.500)
16 2.34 (0.092) 7.53 (0.29) 12.70 (0.500)
14 3.50 (0.138) 10.99 (0.43) 19.05 (0.750)
12 4.01 (0.158) 12.59 (0.50) 19.05 (0.750)
10 4.65 (0.183) 14.60 (0.57) 25.40 (1.000)
8 6.35 (0.250) 19.94 (0.79) 31.75 (1.250)

Type Teflon Wire O.D.

Size
AWG.
O.D.
mm (inch)
Circumference
mm (inch)
Minimum Recommended Label Height
mm (inch)
22 1.52 (0.060) 4.77 (0.19) 7.62 (0.300)
20 1.73 (0.068) 5.43 (0.21) 7.62 (0.300)
18 2.01 (0.079) 6.31 (0.25) 12.70 (0.500)
16 2.26 (0.089) 7.10 (0.28) 12.70 (0.500)

Breakdown of Wire Marking Abbreviations

Common abbreviations in wire marking include:

  • AWG: American Wire Gauge, a standardized system for determining the diameter of conductive wires. The larger the AWG, the smaller the physical size of the wire—for example, 18 AWG is approximate to 2mm in diameter.
  • O.D.: Outside Diameter, which is the diameter of a cable.
  • PVC: A synthetic plastic polymer material that is widely used in cable and wire insulation, as well as in vinyl labels.
  • THW Wire: This is a single conductor that has flame-retardant, moisture-resistant, and heat-resistant insulation. It is generally used for feeder and branch circuits, and in building wiring. It is rated 75°C wet or dry.
  • THHN Wire: This is a single conductor that has flame-retardant and heat-resistant insulation. It is generally used for certain appliances, control circuits, and machine tool wiring. It is rated 90°C dry.

Printing Wire Markers

An industrial label printer makes wire marking easy. If you have your own label printer onsite, you’ll be able to create all the wire markers you need, even in large batches. You can also customize labels to adapt to the task at hand. With durable labels that resist environmental elements, water, and chemicals, industrial printers provide everything you need to tackle wire marking projects successfully.

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