The field of electrical wiring will always be one that demands the very greatest precision. After all, it isn’t only the performance of a given electrical installation that depends on the utmost precision being achieved – the system’s reliability, safety, and compliance hinge on it, too.
If you are reading this as a UK-based electrician, installer, or DIY enthusiast, you will probably be aware that the metric system predominates when it comes to cable sizing in this part of the world. Wire sizes here are typically measured in square millimetres (mm2).
However, the fact that you are reading this article indicates your work may have recently brought you into contact with a different cable measurement system: American Wire Gauge, or AWG. You may, for instance, be dealing with American-sourced equipment, imported cables, or international specifications.
So, in this article, we will put the microscope on what AWG is. Along the way, we will also explain what kind of impact this system will have on your wire sizing processes when you are working on electrical projects.
An Introduction to American Wire Gauge
AWG is the United States’ standardised and predominant system for denoting the diameter – and thus the cross-sectional area, or CSA – of electrically conducting wire. As its name implies, AWG sees widespread use elsewhere in North America, too.
For the purposes of understanding AWG and its relationship with square millimetres, it is greatly useful to know how this scale works. The system assigns a “gauge” number to wires, based on the number of times a piece of metal is drawn through a die to reduce its thickness.
A crucial thing to understand about this logarithmic scale, is its inverse nature; in other words, a lower AWG number means a thicker wire.
For example, 10 AWG is chunkier than 18 AWG. So, the former is more capable than the latter of handling a greater amount of current without overheating.
Why Should People in The UK Care About AWG?
To refer back to what we mentioned above, here in the UK, we adhere to the International Electrotechnical Commission (IEC) metric standards, where wire size is given as the CSA in mm2.
However, references to AWG still manage to crop up frequently, even for British audiences. Mentions of AWG appear, for instance, in automotive or aviation wiring, or when Britons purchase cable online from global suppliers.
There can often be occasions and circumstances, then, that require people in the UK to match AWG numbers to metric equivalents.
This, in turn, brings a need for accurate conversions. After all, any mistakes with the calculation could easily lead to undersized wires (thereby risking fires) or oversized wires (which would represent a waste of money and space).
3 Reasons Why AWG Matters for Wiring Projects
Whether or not you need to convert between AWG and mm2, there can be no question about the critical importance of choosing the right AWG for a given application.
The reasons for this encompass the likes of:
- Current Capacity (Ampacity)
This is the most crucial factor. Thicker wires (expressed as lower AWG numbers) have a reduced level of electrical resistance, compared to thinner wires (with higher AWG numbers). This means they can safely carry a higher current (amperage) without overheating.
By contrast, if you were to use an undersized wire for a circuit with high current demands, this would represent a serious fire hazard.
- Voltage Drop
Over longer distances, electrical resistance within a given wire brings about a drop in voltage. This can result in equipment operating inefficiently, or even failing to work at all.
By using a thicker wire (one with a lower AWG number), you can greatly help to minimise voltage drop as an issue in your electrical installation. This, in turn, can allow you to make sure the correct voltage is delivered to a particular device.
- Compatibility
Connectors, terminals, and other hardware are designed to accommodate a particular range of wire sizes. In the event, then, of you using the wrong gauge, this could lead to poor electrical connections, or it might stop the wire from fitting properly.
The Right Online Tool Can Greatly Help You with Cable Sizing
It is worth remembering that you won’t necessarily be forced to depend on manual calculations when your work requires you to figure out what diameter and CSA a particular AWG number is the approximate equivalent of.
It is a quick and easy process, for example, to explore cable sizing using the AWG to metric wire conversion calculator on the website of RS, the leading electrical component supplier.
We would suggest you have this free browser-based tool bookmarked. This way, the next time you are specifying cables, you will be able to simply click through to it to ensure you have your numbers right. As a result, you will be able to wire with confidence, almost irrespective of your project.
