A standard electric water heater typically draws 18.75 amps at 240 volts.

A standard electric water heater with a 4,500-watt heating element operating at 240 volts draws approximately 18.75 amps. This amperage represents the maximum current draw when the heating element is actively working to heat water. The actual amperage varies depending on the water heater's wattage, voltage, and whether it's a single or dual-element model.

Water Heater Amperage by Wattage and Voltage

Calculating Amps for Your Water Heater

Calculate amperage using the formula: Amps = Watts ÷ Volts. For a 4,500-watt element at 240 volts: 4,500 ÷ 240 = 18.75 amps. Dual-element heaters draw current alternately, not simultaneously, reducing peak amperage requirements. Always verify specifications on your unit's nameplate for exact values.

Breaker and Wire Size Requirements

Electric water heaters require dedicated circuits with proper breaker sizing. A 4,500-watt heater needs a 30-amp double-pole breaker with 10-gauge wire. For 3,000-watt units, use 20-amp breakers with 12-gauge wire. Undersized breakers cause nuisance tripping; oversized breakers create fire hazards. Follow NEC guidelines for safe installation.

Factors Affecting Water Heater Amperage Draw

• Element wattage: Higher wattage means higher amperage
• Voltage: 240V units draw fewer amps than 120V units of same wattage
• Heating stage: Only active elements draw current
• Temperature setting: Higher settings increase heating cycles and average draw
• Recovery time: Longer recovery periods mean more frequent heating cycles