Drill Bit Size For Wires

Drill bits are essential for DIY projects. You can use it for many materials such as wood, concrete metals, and many more. When you use it for wiring, the hole should be smooth and match the diameter of the wire. Because wire diameter varies with the current and voltage. Normally, we use 1-conductor (1-20 gauge), 2-conductor (10-20 gauge), and 3-conductor (10-20 gauge) cables for many purposes in both DIYs and industrial. When you drill for these wires, you should know the diameter of the wire before selecting a drill bit.

The larger diameter holes are always better, but they can acquire more space than you think. So let’s see what kinds of drill bits are suitable for wires.

Standard Wire Sizes and Insulation Thickness

Wires are available in different diameters and gauges. These gauges are maintained according to IEC organization standards.  Normally, single wire size diameters are available from 0.08mm to 11.6mm. According to the diameter, its voltage and ampers are varied.

Different wire sizes and drill bits sizes
The drill bit size should be equal or more than the wire size

These standard wires are insulated with Poly (Vinyl Chloride) in order to prevent the current leaking. According to the voltage and current, the layer’s thickness varies. As a result of this, the wire diameter will be increased due to this layer.

Conductor Size AWGWire Gauges Diameter (mm)Insulation Thickness (mm)
26 to 16 (0.13 to 1.31)1.3 – 0.40.76
14 to 9 (2.08 to 6.63)1.57 – 2.91.14
8 to 2 (8.37 to 33.6)3.25 – 6.551.52
1 to 0000 (42.4 to 10.7)7.34  11.682.03
Standard wire sizes and insulation thickness for Poly(Vinyl Chloride) Insulations

Drill Bit Sizes For Single Conductor Wires

When you choose a drill bit for a wire, it should be more or equal to the diameter of the wire (including insulation and conductor). So let’s see what are the suitable drill bit sizes for each wire size.

Wire gaugeWire Diameter (mm)Total Insulation Thickness (mm)Hole Diameter (mm)Drill Bit Size in InchesDrill Bit size in mm
17.344.0611.4 15/3211.9
26.553.049.59 25/649.92
35.823.048.86 23/649.12
45.183.048.22 21/648.33
54.623.047.66  5/167.93
64.113.047.15 19/647.54
73.663.046.7  9/327.14
83.253.046.29  1/46.35
92.902.285.18  7/325.55
102.592.284.87 13/645.15
112.312.284.59  3/164.76
122.062.284.34 11/644.36
131.832.284.11 11/644.36
141.572.283.85  5/323.96
151.452.283.73  5/323.96
161.301.522.82  1/83.17
171.141.522.66  7/642.77
181.021.522.54  7/642.77
190.911.522.43  7/642.77
200.811.522.33  3/322.38
Drill Bit Sizes for Single Wires

Drill Bit Size for 2 Conductor Wires

2 conductor wires, double wires, and 2 core cable wires are the same wires that have 2 wires in a single cable.

Both cables are coated with electrical insulations. When you drill a hole for 2 conductor wires you can select drill bit sizes from below table.

I have prepared a guide to find drill bit sizes in inches and mm. It helps to find any drill bit related to the mm or inches easily.

Wire GaugeWire Diameter in mmDrill Bit Size in inches
10/210.531/64
12/29.57/16
14/27.55/16
16/26.55/16
18/24.51/4
20/23.51/4
Drill bit sizes for 2 conductor wires

Drill Bit Size for 3 Conductor Wires

3 conductor wires and 3 core cables are the same in name and have 3 conductive cables inside the single wire.

3 conductor wires have different size gauges. Mostly used gauges are 10, 12, 14, 16, 18, and 20. You can use below drill bits when you drill a hole for 3 conductor wires.

Wire GaugeWire Diameter in mmDrill Bit Size in inches
10/316.763/4
12/315.493/4
14/313.335/8
16/38.383/8
18/36.103/8
20/35.41/4
Drill bit size for 3 conductor wires

When you drill for screws, this guide will help you to find the drill bit sizes for screws.

In Conclusion

Drill bit size is very important for wirings. Always drilled holes should be equal to or larger than the wire size. Normally, wires have conductive cable and insulation thickness. Those are standard sizes. Hence you should know both thicknesses in order to determine the hole diameter.


Tom Mackency

Tom Mackency

Hi, I am Tom Mackency. It has been 10 years that I have been working as a professional woodworker since 2013. I am really enjoying my carrier by creating many kinds of projects in my workshop. But mostly I like for home improvement projects. Home improvement and DIY projects are the most interesting things for me. More than that, the coolest things are power tools. Those are very precious and efficient than a decade ago. So I try to introduce so many things about power tools, woodworking, DIY projects, home improvement and many more interesting topics here.