If a circuit is rewired, extended, or a new circuit is connected, it is important to have knowledge of the accurate ampere value and wire gauge used. New wiring is made with wire conductors that have an accurate size for the ampere rating of the circuit. The high ampere rating of the circuit needed larger electrical wires to avoid extra heat that can melt wires and cause fire. Accurate wire size is shown with an ampere rating and measured with different factors such as the load on the circuit, the number of outlets or light fixtures, and the circuit length. So let’s get started with WHAT SIZE WIRE FOR 20 AMP CIRCUIT?
How Wires Are Sized
- When you buy new electrical wire, you may have seen that there are different types and sizes of electrical wire.
- Different types of wire are used for different purposes, but with any wire, check the wire size, wire gauge, amps, and uses.
- The AWG system is used for wire size measurement. The wire gauge defines the physical size of the wire that is mentioned with numbers that are reversed to the diameter of the conductors.
- Small-gauge wire means a larger diameter. Commonly used wire sizes are 16-, 14-, 12-, 10-, 8-, 6-, and 2-gauge wire.
- Wire size shows the value of current that can carry through the wire easily.
- Current is measured in amperes, and every wire gauge has the highest safe current-carrying capacity.
- For standard non-metallic cable, these amperes and wire gauge capacities help measure the wire size that is required.
Applications of a 20-amp circuit
The 20-amp circuit can be dedicated to a certain device or shared, like a 15-amp circuit.
The 20 amps for 120 volts can provide about 2400 watts of power. On the basis of the NEC circuit, not 80 percent of the maximum capacity for continuous loads is used. So for using 1920 watts on a 120-volt circuit for 3 hours at a time,.
The 20-amp outlet comes with a T-shaped adapter for accepting 20-amp plugs.
The 20-amp circuit’s common uses are:
- Kitchen circuits such as dishwashers, microwaves, toasters, garbage disposal, and blenders.
- Laundry circuits like washing machines.
- Bathroom circuits, such as curling irons and hair dryers.
- office rooms for devices such as computers and printers.
- Garages that come with power tools and car repair equipment.
- AC systems that have large window units.
Applications of a 20-amp circuit
The 20-amp circuit can be dedicated to a certain device or shared, like a 15-amp circuit.
The 20 amps for 120 volts can provide about 2400 watts of power. Based on the NEC circuit, not 80 percent of the maximum capacity for continuous loads is used. So for using 1920 watts on a 120-volt circuit for 3 hours at a time,.
The 20-amp outlet comes with a T-shaped adapter for accepting 20-amp plugs.
The 20-amp circuit’s common uses are:
- Kitchen circuits include dishwashers, Â microwaves, toasters, garbage disposals, and blenders.
- office rooms for devices such as computers and printers.
- Garages that come with power tools and car repair equipment.
- AC systems that have large window units.
- Laundry circuits like washing machines.
- Bathroom circuits, such as curling irons and hair dryers.
Cables for 20-amp circuitsÂ
NM-B Non-Metallic Sheathed Romex CableÂ
- It is a famous cable that is used for indoor 20-amp circuits. It is used for different types of inner wiring when the cable not affected by moisture and does not need more protection. Kitchen, laundry, and bathroom circuits are using NM-B with protection from water sources.
THHN/THWN
- These are copper and aluminum materials in conduit. It is used when wiring is exposed or needs more protection, such as in a garage.
UF-B cablesÂ
- It is used for circuit breakers connected outdoors, like AC systems connected outdoors and garages. It is not used in interiors except for direct exposure to moisture and under sinks.
MC metal-clad cables
- It was used to avoid mechanical protection from mechanical damage, such as in garage workshops, commercial kitchens, and commercial offices.
WHAT SIZE WIRE FOR 20 AMP CIRCUIT?
- The proper wire size for a 20-amp breaker is about 12 AWG copper wire, rated at 75 degrees.
- The 14-gauge wire on the 20-amp circuit is not an accurate size since it is rated for handling 15 AMP.
- The use of 14 AWG for a 20-amp breaker causes overheating and a chance of fire.
- The use of 10 AWG for a 20-amp circuit is possible and safe, but it is a costly process. But it can cause some problems, such as larger wires not being good for terminals on devices rated for 20 amps.
- Aluminum wire is not the best option for a 20-amp breaker and should be replaced with copper wire.
- The aluminum wire size for a 20-amp circuit is also 12 AWG.
- The best option for 20-amp wire is 12 AWG copper wire.
What is the wire gauge for a 20-amp circuit?
- #14 AWG for 20A ampacity.
- #12 AWG for 25A ampacity.
- #10 AWG for 35A ampacity.
The 14 AWG wire is not used for a 20-amp circuit, but 12 AWG and 10 AWG wires are.
The use of the NEC 80% rule helps you find the cause for measuring the minimum ampacity of wire for 20-amp services.
20 Amp Wire = 20A × 100% / 80% = 25A Ampacity
- So there is a need for about 25A ampacity for 20 amps and 14 AWG for 20A ampacity.
Which is the best wire gauge for a 20-amp breaker?
The 12AWG wire is normally copper wire with a 25A ampacity for the median temperature (75°C or 167°F).
If sending current away from the subpanel for a certain distance, there is a need for a larger wire.
What Size Wire Is For 20 Amps At 100 Feet Away?
For distance 100feet and more than voltage will losses. For getting 20 amps complete on the circuit’s second end, there is a need to boost the amps to handle voltage losses.
20 Amp Wire = 25A × 1.2 = 30A Ampacity
So 12 AWG wire with a 25A ampacity is not enough. #10 AWG wire is the best to use. It comes with a 35A ampacity, a larger needed for a 30A ampacity.
minimum amp for a 20-amp circuit at any distance:
- 50 feet from the sub panel. #10 AWG wire.
- 100 feet from the subpanel. 30A Ampacity, #10 AWG wire.
- 150 feet from the sub panel. Ampacity: #10 AWG wire.
Different Wire Length
if wire length is larger than some dozen feet, for keeping low energy losses, wire ampacity can be increased with 10% for every 50 feet of the wire.
- 50 feet wire: Ampacity = 25 Amps x 1.1 = 27.5 Amps
- 100 feet wire: Ampacity = 25 Amps x 1.2 = 30 Amps
- 150 feet wire: Ampacity = 25 Amps x 1.3 = 32.5 Amps
- 200 feet wire: Ampacity = 25 Amps x 1.4 = 35 Amps
| Wire Length | 60°C/140°F | 75°C/167°F | 90°C/194°F |
| <50 feet (25 Amps) | AWG 10 (30A) | AWG 12 (25A) | AWG 12 (30A) |
| 50 feet (27.5 Amps) | AWG 10 (30A) | AWG 10 (35A) | AWG 12 (30A) |
| 100 feet (30 Amps) | AWG 10 (30A) | AWG 10 (35A) | AWG 12 (30A) |
| 150 feet (32.5 Amps) | AWG 8 (40A) | AWG 10 (35A) | AWG 10 (40A) |
| 200 feet (35 Amps) | AWG 8 (40A) | AWG 10 (35A) | AWG 10 (40A) |
How To Identify Wire Size
For wiring in a building or home, there is a need to find the current of the wire, which can be measured in amperes. Such a 30 amp wire size needed a different wire gauge as compared to 10 amp or 40 amp wire.
AWG is the standard method for finding and choosing wire size; this value ranges from zero to 40 AWG. The lower number means thicker diameters of wire, and more can flow.
During wiring buying, the product label shows the wire size in AWG; in some conditions, 10 is 10 gauge wire, 20 is 20 gauge wire, etc.
What Size Wire for a 20 Amp Circuit Breaker?
For a 20 Amp circuit, the recommended wire gauge is 12 AWG for copper wire use and for aluminum wire is to use ten gauge wire. These gauges can easily handle about 20 ampere current. So connected devices easily work with these wiring.
The factor for choosing Gauge Wire for 20 Amp Breaker
VoltageÂ
- The voltage of any circuit helps to define the highest current that can easily flow in the wire. In the case of standard household circuits that use 120V or 240V the best wire for 20 amps load is 12 AWG wire
Length:
- Wire length is also the main factor that affects the gauge used. Longer wires face high voltage losses since have high resistance. If the circuit is longer than 50 feet, use larger gauge wire for handling voltage losses
Material:
- The ampacity of the wire is affected due to the material of the wire. Copper wire is the best option for wiring since it has good heat dissipation factors and is conductive as well. Aluminum wire was also used but it needed a larger gauge for the same ampacity because it is less conductive as compared to copper.
Ambience:
- The ampacity of the wire is also affected due to environmental temperature where it is connected. High temperature reduces the current carrying features of the wire. In these conditions, larger gauge wire is used for handling low-capacity
Why Gauge Wire Important?
The gauge wire defines the wire thickness and its features for handling current in a safe way. Every gauge comes with a certain value of ampacity, which is a high current that can handle without any damage or overheating.
Using wire of small gauge for high current causes overheating effect. That can also affect the insulation of wire and the chances of fire.
Different wire gauges are used for certain applications such as 60 Amp, 70 Amp, 100 Amp, 200 Amp,
Can we Use a #10 AWG or 14 AWG in place of #12 AWG Copper Wire on a 20-Amp Breaker?
If we use a ten gauge wire in place of 12 AWG for a 20A breaker it can used since a ten gauge wire has a feature to handle 30A.
Using 14 gauge in place of 12 AWG for a 20A breaker is not referred to. Since 14 gauge wire handle just 15 Ampere so it can cause fire for 20 amp circuits.
Faqs
- The 20-amp circuit, which has a 20-amp breaker or fuse, comes with 12-gauge or 10-gauge wire. To find out if the circuit is 15 or 20 amps, check the corresponding breaker or fuse in the breaker panel.
What size cable do I need for a 20-amp supply?
| Conductor Size | Current | Maximum power (watts) |
|---|---|---|
| 1.25 mm2 | 13 amps | 3120 Watts |
| 1.5 mm2 | 15 amps | 3600 Watts |
| 2.5 mm2 | 20 amps | 4800 Watts |
| 4.0 mm2 | 25 amps | 6000 Watts |
What size of cable should be used when the current is 20 A?
| Maximum Amps | 7 | 20 |
|---|---|---|
| Gauge (wire size) | 18 | 12 |
- The accurate wire size for a 20-amp breaker is 12 AWG copper wire. It is rated at 20 amps for 75 degrees. The 14-gauge wire for a 20-amp circuit is not the correct size and is rated for handling about 15-amp  residential applications.
- The highest current-carrying capacity of 1.5 sq mm Cu wire is about 20 A. It is used for loads that use no more than 15A. 1.5 sqmm Cu wire
- The maximum current that can be obtained is about ten amperes, and the wire size for a 1.5-ton inverter AC can be about 2.5 mm2 or 14 gauge for working safely. 6mm2 or 10-gauge wires are used for a 3-ton air conditioner that works on single-phase power. That is for a 1.5-ton AC wire.
- It is suggested to use 2.5 mm square wire for a circuit that has a current rating of 13.5 amps and can handle about 25 amps. The wire can carry more current than its rated capacity, but overloading can be a risk.
- 2.5mm Twin and Earth are used for indoor cables. The common use for this cable is for circuits that provide power to sockets. It is created with two cores and an earth core that are covered with green and yellow sleeves when installed.
