A 1500-watt heater on a 120-volt circuit thus needs a breaker of 15.6 amps. Because a 15-amp breaker would be too small, you need a breaker with the next highest rating, which is 20 amps.
For example, water heaters operating at 120V will draw 8.3 - 16.6 amps of current.
If you only have central heating, the furnace will likely be on a dedicated 120-volt circuit instead. Electric furnaces, electric water heaters, electric clothes dryers, and electric ranges and ovens all run on 240 volts as well. This means each one needs a dedicated circuit.
The NEC requires circuit breakers to be sized at 125% of the intended load. Most residential water heaters require a 30-amp circuit breaker.
The National Electrical Code (NEC) specifies that the breaker size must be 125% of the continuous load. This means, for a water heater drawing 20 amps, you would need a breaker rated for 25 amps (20 amps * 1.25 = 25 amps).
A 10 gauge circuit is rated for 4500 watt heater. Use a 30 amp breaker for a 4500 watt hot water tank. If a smaller 3800 watt tank is installed use a 20 amp breaker. The breaker should be rated for AC or hot water tank duty.
However, the NEC also allows the use of a wire size of 12 AWG for a 25 amp breaker. As long as a GFCI or an AFCI protects the wire. These devices provide additional protection against electrical hazards and can prevent fires and electrical shock. Sadly, not many electricians will advise choosing this approach.
Continuous Load Considerations
According to the NEC Code, a circuit breaker must be sized at 125% of the continuous load. This means that if your water heater has a continuous load of 16 amps, you would need a circuit breaker that can handle at least 20 amps.
When the breaker is tripping, it is almost never a good idea to replace it with a larger one. Here's why: It increases the risk of fire. If the breaker is tripping because it's overloaded (say, drawing 25 amps on a 20-amp breaker), increasing the size may cause the wire or the receptacle to overheat.
Dining rooms usually require a separate 20-amp circuit for an outlet that can be used for microwaves, window air conditioners or other appliances. Stairways require three-way switches at the top and bottom of each flight of stairs so lights can be turned on or off at either end.
1500 watts at 120 volts is 12.5 amps and a water heater is a continuous load under NEC Section 422.13 so can't exceed 80% of the circuit's over-current protection. 12.5 amps it is just a bit too much to be on a 15-amp breaker continuously but would be fine on a 20-amp breaker and 12-gauge copper conductors.
Electric water heaters require a 240-volt dedicated circuit, which serves only the water heater and no other appliances or devices. The circuit wiring typically includes a 30-amp double-pole breaker and 10-2 non-metallic (NM) or MC cable.
On average, most space heaters draw 1500W of electricity per hour and 12.5 amps when operating at 120V. The amperage range of household space heaters operating at 120V is between 5 and 15 amps. The space heater amps can vary depending on the temperature setting.
Yes, but experts don't recommend wiring your water heater this way.
1500w / 120v says 12.5 amps. So I installed 15 amp breaker and pulled new 14-2 wire. Upon purchase the manual states to run 12 gauge on a 15 amp breaker.
Installing a circuit breaker with a larger amperage than recommended increases the risk of overheating, which can potentially ignite surrounding materials or wiring within the system.
Overloading the Wiring: A 15-amp breaker is typically connected to 14 AWG (American Wire Gauge) wire, which is not rated to handle the 20-amp current. Upgrading the breaker without upgrading the wiring can lead to overheating, melted insulation, and potential electrical fires.
Ideally, you should spread as many outlets around your home as possible and assign them to a single circuit. Just keep in mind the maximum load for a single circuit. A good rule of thumb is to assume that there will be a maximum power draw of 1.5 amps for each outlet, allowing 10 outlets for a single 20-amp circuit.
10/2 MC metal cable is the most popular type of water heater cable as it is flexible in itself and offers protection against mechanical damage. This is the all-around perfect cable for water heaters, especially in areas where cables might be exposed to mechanical damage and moisture.
Most modern electric water heaters utilize 18.8 amps with 240 volts and 4,500-watt heating elements. If you have a gas water heater, expect it to use 12 amps with 115 volts. The average 40-gallon tank requires a 30-amp breaker.
The issue with double tapping is you could technically have a loose connection or an overloaded breaker since the breaker is not designed for two wires. A loose connection can potentially spark or arc. Furthermore, an overloaded breaker could continuously trip or overheat.
If you're using 12-gauge wire on a 20 amp power load, that means you can run the circuit almost as long as 57 feet without experiencing more than a five percent volt drop. Many online sources suggest going no longer than 50 feet for a circuit.
A 25 amp DC circuit breaker protects your DC electrical circuit from current overshoots over 25 amperes. 25 amp DC circuit breakers find use in applications requiring a higher current capacity compared to a 20 amp breaker.
Note that a 14 gauge wire on a 20 amp circuit is not the correct size, as it is only rated to handle up to 15 Amp in residential applications. Using 14 AWG for a 20 Amp breaker will result in overheating and a risk of electrical fire. Using a 10 AWG wire for a 20 amp circuit is possible and safe but not cost-effective.