Electrical Wire Sizing Chart

Wires are used to provide electricity to our homes, offices and workplaces. It is very important to have properly sized wires to provide brighter lights and high performance of tools and gadgets. This article aims to provide some basic knowledge on electrical wire sizes, wire specifications and table of electrical wire size requirements by the American Wire Gauge (AWG). This is just an overview of the wire specifications and wire sizes and should not be used as an exact source. You should consult the experts regarding recommendation for your specific needs.

Wire Size
The primary consideration to be taken before wiring a new circuit is the wire size and wire type. The current ratings of the power loads is the factor that is to be considered when determining the wire size and wire specifications. If the current flow is fast and the wire size small, the wire will get heated up too soon. This melts the insulation around the wire that can lead to a dangerous situation. The continuous high temperature running through the wire causes corrosive effect at the terminal connections of the wire. This makes the stranded wire lose its strands one at a time and the solid wire to become brittle. The wire becomes smaller and there is increase in heat. Thus, this increase in current causes the wire to break off that may lead to a serious complication. The hanging live wire inside the control panel may get too hot causing the insulation to melt and lead to a fire hazard.

The information on wire specifications should be based on the insulation of the wire and its temperature ratings. The environment, temperature rating and the application of the wire should be considered when selecting the appropriate wire specification and wire type. The wire should be used according to the National Electrical Code (NEC) electrical wire specification. You should check whether the wire is rated for direct burial underground or not. Ask the local electrical inspector of your area for rules regarding wire specification for the type of wire and its application.

Table of Electrical Wire Size Requirements
You need to follow a wire chart table that will serve as a guideline of ampacity or copper wire current carrying capacity. You should follow the Handbook of Electronic Tables and Formulas for American Wire Gauge to refer to electronic wire sizing chart. One needs to consider the voltage drop, insulation temperature limit, thickness, thermal conductivity, air convection and temperature. You should consult the expert that is your local electrician and find out what is required and legal in your area. There are many websites that offer electrical wire sizing charts online, for your reference.

Electrical Wire Size Calculator
The American Wire Gauge (AWG) system adopted in 1857 has defined a method for electrical wire size calculator. The method has two basic objectives, that is, the ratio of the largest size with the smallest size would be an integer. The second objective, the resulting gauges would generally correspond to the proprietary gauges used at the time.

The size of gauges larger than 0 gauge are calculated as for example, 1 is 89% of gauge 0, then gauge 0 will be 89% of gauge 00, that will be 89% of gauge 000 and so forth. The AWG standard defines 0000 gauge wire as 0.46 inches and 36 gauge as 0.005 inches.

The electrical wire size calculator uses the formula by the AWG wire sizes. The formula is as follows:

Dn = (D0) r^{( (N- (d + n) ) / N)}

Where,
Dn = Diameter of n gauge wire
r = Ratio between the largest and the smallest wire
N = Number of draws needed to obtain the smallest wire from the I
d = Offset of the largest gauge from 0.

In order to calculate the wire size, substitute the values in the formula as follows:

The standards used are, D0 = 0/005, r = 0.46/0.005 = 92 and d = -3.

Therefore, the formula is now:

Dn = 0.005 in. x 92^{( ( 36-n) / 39)}

Dn = 0.127 mm x 92^{( ( 36-n) / 39)}

The gauge is calculated using log:

n = -39 log₉₂ (Dn/0.005 inch) + 36 = -39log₉₂ (Dn/ 0.127 mm) + 36.

This is just a fair idea for determining electrical wire size. You should follow the guidelines stated in the AWG Handbook of Electronic Tables and Formulas and take advice from your local electrician. This article as mentioned earlier is just meant to help you understand the uses of electrical wire sizing chart. You should follow the wire chart when adding or changing new circuit for your home, office or workplace. You should take ample care regarding the wire specifications laid down by National Electrical Code (NEC). You should carefully follow electrical safety at home and your workplaces to avoid any unfortunate electrical mishap. This will help protect your property and many innocent lives from a possible fire hazard due to short circuit.