Energy & electrical
Heating-element resistance
- where
- element resistance (Ω)
- rated supply voltage (V)
- rated heater power (W; any unit you pick is converted)
Explain this equation
Works out the hot resistance of a heating element from its rated voltage and power. Use it to compare a measured element resistance with what you would expect.
U is the rated supply voltage. P is the rated power. R is the element's resistance when running.
Power is U² / R for a resistive load, so rearranging gives R = U² / P. Higher power means lower resistance, because more current must flow.
Sense check: a 3 kW element at 230 V is about 17.6 Ω. A 6 kW element at the same voltage is about 8.8 Ω.
Watch out: resistance varies slightly with temperature, so a cold reading can differ a little. This is not an insulation resistance test.
Enter your values to see the result.
Good to know
Resistance can vary with element temperature; not an insulation or electrical-safety test.
Sources
Results are arithmetic only. Worked examples are not recommended design settings. This library does not provide automatic gas pipe selection, live gas tightness tests, purging procedures, combustion acceptance limits, installation approval or commissioning certification. Manufacturer data and the applicable current method remain essential.