Free tool
Water Heater Element Sizing
Confirm the right wattage for your tank and check the circuit can carry it. Never fit a higher-wattage element than the original without having the circuit upgraded first.
Stamped on the element flange, or on the tank rating plate.
240V for most Canadian tanks; some are 208V.
From the panel label for the water heater circuit.
- Current draw
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- Minimum circuit
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- Healthy resistance
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Enter the wattage and voltage printed on your rating plate or stamped on the old element's flange.
Before you touch the tank
Kill the breaker, confirm it is dead at the element terminals, and drain the tank below the element before removing it. An element energised in a drained tank burns out in seconds, and one removed from a full tank floods the room.
The 125% margin is the continuous-duty allowance electrical codes require for loads that run for long periods. It is why a 4500 W element at 240 V needs a 30 A circuit rather than a 20 A one.
Water heater element questions
Can I fit a higher-wattage element to heat water faster?
No — and this is the single most dangerous mistake in element replacement. The circuit, the breaker and the wiring in the wall were all sized for the original wattage. A larger element draws more current than that wiring was built to carry, and the breaker is the only thing between an overloaded circuit and a fire. Match the original rating, or have an electrician upgrade the circuit before changing anything.
Why does the calculator want 125% of the current draw?
Water heating is a continuous load — the element runs for long stretches rather than cycling briefly. Electrical codes require continuous loads to be sized at 125% of their actual draw so the conductors and breaker are not running at their limit for hours. That margin is why a 4500 W element at 240 V, which draws 18.75 A, needs a 30 A circuit rather than a 20 A one.
Where do I find the wattage of my existing element?
It is usually stamped on the flange of the element itself, and it is also on the tank rating plate along with the voltage. If both are illegible, photograph the element and the plate and send them — we can usually identify the rating from the physical part.
Both elements are the same wattage. Should I replace both?
Usually yes, for the same reason as a kiln set: they have the same hours and the same mineral scaling on them, so the second failure tends to follow the first. The tank is already drained and open, which is most of the labour, so doing both at once costs little more than doing one.
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Send us the rating and we will match it
Wattage, voltage and the mount style off the old element. A photo of the flange is enough if the stamp is legible.