Wire gauge can be a confusing concept, especially since smaller numbers actually indicate larger wire gauges! American Wire Gauge (AWG) is a specification that provides specific wire sizes, ranging from 0000 (the largest quarter) to 40 (the smallest). The term “wire gauge” refers to the manufacturing process of the wire, where it is drawn through a die. Essentially, a higher gauge indicates the number of times the wire is pulled through the die to reduce its diameter. This means that the size of the wire doubles every 6 steps.
People often ask, “What is AWG or American Wire Gauge?” Besides the name, it’s important to note that as the wire size increases, the numbers actually get smaller! Before you start working with wires, it’s crucial to know the appropriate wire size for your needs.
What is AWG: The Basics
To further understand AWG, let’s delve into the fundamentals. AWG is a specification that provides specific wire sizes. The sizes range from 0000 (the largest quarter) to 40 (the smallest). Apart from determining the wire size, the term “wire gauge” also refers to the resistance of the wire. Keep in mind that the size of the wire doubles every 6 steps. However, when discussing wires in terms of their electrical uses, we primarily focus on their resistance.
Wire Gauge and Current
When it comes to wires, the gauge of the wire largely determines the amount of current it can safely carry and its resistance. Additionally, the wire gauge also indicates the weight of the wire per unit length. This is because most current wires are primarily made of copper.
What about Aluminum?
Although aluminum wire is rarely used in residential construction, except for larger gauge stranded aluminum wire, it was widely used in homes built or remodeled in the 1960s and 1970s due to copper shortages. Aluminum is a good conductor but has a low ampacity, meaning it has a lower threshold before the cable starts melting. Additionally, aluminum expands and contracts more and is more prone to corrosion. If you have aluminum wiring in your home, it is advisable to consider updating the system or regularly checking its condition.
CPSC Steps In
Solid aluminum wire is not as reliable as copper wire. Older aluminum wire is softer and more prone to thermal expansion, which can cause arcing and overheating. Additionally, aluminum wire is more prone to oxidation than copper wire. Applying an anti-oxidant paste to the ends of aluminum wire is always a good idea.
American Wire Gauge, Current, and Cable Diameter
Let’s circle back to copper wire and gauge measurements. The gauge ratings directly correlate to cable size and the amount of current that can flow through the wire. The table below illustrates this relationship:
As shown, larger wires (smaller gauge numbers) can support more current, which is why larger breaker sizes are required.
AWG (American Wire Gauge) vs. SWG (Standard Wire Gauge)
In the United States, we use the American Wire Gauge (AWG) system. It was developed for the electrical industry and is designed for use on non-ferrous metals that do not contain iron. The AWG number corresponds to the wire’s resistance. A thicker wire has a lower resistance and a lower gauge number, allowing more electrons to flow. Conversely, thinner wires have higher resistance and larger gauge numbers.
The Standard Wire Gauge (SWG) system, developed in the UK, is utilized for ferrous and non-electrical applications. SWG gauge numbers correspond to the number of times the metal needs to be pulled through the formwork to achieve the desired diameter. As the wire is pulled through, it tapers, resulting in a higher SWG number.
Determining the Right Size for Electrical Circuits
To determine the appropriate wire gauge for your application, it is crucial to consider the amperage (current) expected to flow through the wire. Standard home electrical circuits usually have a circuit breaker rated at 20 amps (15 amps or 14 gauge for older homes and specific uses). If more power is drawn than the circuit or cable is designed for, the breaker will trip or shut off the power to prevent reaching the wire’s melting point.
A helpful rule of thumb is the 20% rule – only utilize 80% of the wire’s capacity. This compensates for variables such as wire length, swelling, and surges. For instance, if you are wiring your house or adding a new circuit, using a 2/12 cable and a 20A breaker is recommended. However, for high-current appliances like hair dryers or electric ovens, it is advisable to use products that comply with compatible wire specifications.
I hope this article has provided you with valuable insights into AWG or American Wire Gauge. If you have any questions or concerns, feel free to post them in the comments below!