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What Size Wire Do I Need?

Aug 3

Electrical wires come in different sizes. The wire's size determines how much amperage it can handle. To determine what gauge of wire you will need, however, it is important to know the gauge. A 30 amp wire requires a different gauge than a wire that is 10 amp (A) or 40 amp (A). This value is known as American Wire Gauge (AWG) and can range from 0-40 AWG. The higher the number, the larger the wire's diameter and the greater its power.

Why is wire size important?

The circuit breaker's wire gauge is used to determine its size. A circuit breaker's purpose is to stop the current flow before it is damaged. Using a wire gauge that is too small can lead to overload. Even if the wire is damaged, the breaker won't trip if there is too much current flowing. A wire gauge that is too big for the circuit breaker can cause a trip, even though the load is not greater than the wire's rating.

Common Wire Sizes

There are several common sizes of wire used in homes. These wire sizes are common and can be used for a variety of applications.

  • 10 Amp Wire Size For appliances such as toasters and vacuum cleaners, refrigerators, vacuums, vacuums, hair dryers, and dishwashers, use a #16 AWG cable.
  • 30 Amp Size: A #10 gauge wire is suitable for powering any RV's appliances or air conditioners.
  • 40 Amp Wire: You will need a #8 AWG cable to power your electric cooktops or other electric cooking appliances.

A 50 amp wire size is required for breakers that are connected to multiple appliances on an electrical panel, such as a stove or dryer. A #6 AWG cable can support a maximum of 50amps.

How do I identify wire size?

The AWG size of the wire will be indicated on the label when you purchase wire or cable. Sometimes, the number is all that is listed. A 10 gauge wire would be labeled "10", for example. If the format is 10/2, it means that there are two conductors or wires in the cable. A label might also include a "G" (or "w/G"), which means that the cable does not have a ground wire.

Other Factors That Affect Wire Size

The amperage requirement should not be the only factor when choosing the right size wire. The length of the wire is an important consideration. The next-largest wire size should be used if the wire is more than 100 feet in length, or if it's within a conduit (reducing heat dissipation). A 30 amp wire should be amplified by 10% for wires that extend beyond 50 feet of the subpanel, 20% for wires up to 100 feet, and 30% for wires up to 150 feet. You should increase amps by 40% for a 200-foot wire. This will require a wire capable of handling 52.5 amps.

It is also important to consider the material of the wire. Electrical wire is usually made from brass, copper, or silver. Aluminum wire is less popular and may require a different AWG requirement. Aluminum has 61% less conductivity than copper and weighs 30% more than copper.

The National Electric Code (NEC) also requires that you follow these requirements. The NEC states that 30A wires cannot be used for service purposes. Branch circuits can only handle 80% of their maximum load (any load). This means that a wire must be able to handle at least 37.5 amps or a #8 AWG. The same applies to a 110/120V, 220 V, and 240 V circuit.

To prevent heat buildup and a trip of the breaker when switching on appliances, the NEC requirement was put in place. It is also used to calculate the number of outlets in a circuit.

Call the Oakland Electrician Group to Wire/Re-Wire Help

To ensure that the correct size wire is used when replacing or installing electrical wiring, it is important to consider both capacity requirements and other factors. All of our electricians are licensed and insured. They are familiar with the different wire gauges that work best for each application. You can request service online or call the Oakland Electrician Group if you need help installing new outlets or electrical repair.


Oakland Electrician Group

(341) 208 2060

Oakland, California, USA