Circuit breaker size refers to the amperage rating that determines how much current a breaker can safely carry before tripping. For water heaters, sizing is based on the unit’s wattage and voltage, with a safety margin to prevent nuisance trips while still protecting the circuit.
/ˈsɜːkɪt ˈbreɪkər saɪz/
Circuit breaker size refers to the amperage rating that determines how much current a breaker can safely carry before tripping. For water heaters, sizing is based on the unit’s wattage and voltage, with a safety margin to prevent nuisance trips while still protecting the circuit.
How do you size a circuit breaker for a water heater?
Divide the heater’s wattage by voltage to find amperage, then choose a breaker with an appropriate safety margin.
Source: The Cooling Company
Breaker size depends on wattage, voltage, and safety margin.
A 4,500‑watt water heater on a 240‑volt circuit draws about 18.75 amps, so a 30‑amp breaker is commonly used for safe, reliable operation.
Always have a licensed electrician verify breaker sizing and code compliance for water heater circuits.
“Always have a licensed electrician verify breaker sizing and code compliance for water heater circuits.”
Modern breaker standards evolved in the early 20th century, greatly improving electrical safety.
Can I use a larger breaker than required?
No. Oversizing can allow excessive current and increase fire risk. Use the correct size for the circuit.
Why does my water heater breaker keep tripping?
Common causes include undersized breakers, wiring issues, or a failing heating element.
Do tankless water heaters need bigger breakers?
Often yes. Many electric tankless units require multiple high‑amp breakers due to higher power draw.
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