If you’re adding an outlet, you need to use wire the same gauge as the existing wiring. How do you tell what size your old wiring is?
How to Use Pocket Change to Determine Wire Sizes
Updated on Jan. 28, 2025
If you’re getting ready to do some electrical work at home, it’s important to know the wire sizes you’ll be working with. Using the correct size wire facilitates proper electrical flow and prevents overloads or hazards, as different-sized wires are designed to carry specific electrical loads. While precision is key, DIYers with electrical experience can use pocket change to get a quick estimate of wire sizes. By comparing the wire’s thickness to the thickness of nickels and dimes, you can get a rough idea in a pinch. However, if you’re new to electrical work, it’s best to use a wire gauge to eliminate any guesswork and ensure safety.
What size is that wiring, anyway?
If you’re adding an outlet, you need to use wire the same gauge as the existing wiring. How do you tell if your old wiring is 12-gauge or 14-gauge? Here’s a simple visual. Twelve gauge is about the thickness of a nickel, and 14-gauge is about the thickness of a dime. Also, look at the breaker for the circuit in question to see if it’s a 15-amp or a 20-amp breaker. A 20-amp circuit requires wire that’s 12-gauge or larger.
FAQs
Why is wire size important?
Choosing the correct wire size is crucial to your electrical work’s safety. It also reduces the likelihood of future issues or costly repairs. If a wire is undersized for the amount of electrical current it’s carrying, it can overheat, causing a fire or damage to fixtures or appliances. Incorrectly sized wires can also trip circuit breakers, leading to power failures. Circuit breakers that repeatedly trip should be explored for incorrectly sized wires somewhere in the circuit.
What wire gauge should I use for common household circuits?
Low energy-draw fixtures like lights and bedroom outlets will use 14 American Wire Gauge (AWG) with 15 amp circuits. 12 AWG wire will be used with 20 amp circuits to provide a bit more power to kitchens, garages and outdoor lights. 30 amp circuits power larger appliances like water heaters and clothes dryers with 10 AWG wire. Electric ranges, central air conditioning units and electrical vehicle charging stations require a 50 amp circuit, which needs 6 AWG.
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