How to Test a Heating Element

This is a general guide to test any type of heating element for failure using an multimeter to measure the resistance of the element.

Method 1
Method 1 of 2:
Testing A Conventional Element

  1. Image titled Test a Heating Element Step 3
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    1
    Know the resistance of the element should be this can be calculated using known values:[1]
    • R = (V x V) / P [Where V is the voltage powering the element, P is the power the element uses and R is the resistance.] (An example calculation is shown in the tips section)
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    2
    Now we know what resistance we are looking for we can check the element.
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    3
    Use a multimeter to find resistance. Set the multi-meter to the resistance setting with an appropriate measuring scale selected. Measure the resistance by disconnecting the heating element from any power source, and connecting the multimeter leads to the terminals of the heating element.[2]
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Method 2
Method 2 of 2:
Testing A Water Heater Heating Element

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    2
    Drain the water from the water heater. Locate the water valve at the bottom of the water heater. Attach a garden hose to the emptying valve and turn the valve using a wrench. You will notice a relief valve near the top of the water heater, you can flip the handle up to open it. By doing this it will allow air into the tank causing the water to flow out more quickly.[4]
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    Wait for the tank to fully empty. Locate the heating element.
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    4
    Remove the electrical wires leading to the heating element.
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Then remove the heating element using a socket or a wrench and you can now check the element as shown in first method.

Community Q&A

  • Question
    Why do I multiply two voltages?
    Community Answer
    Community Answer
    Power formula states that P=IV. Ohms law states that V=IR or I=V/R. Substitute V/R for I in the power formula gives us P=V/R*V or V*V/R, so resistance of the element should be the voltage squared divided by the power.
  • Question
    How can I tell if the switch or the element is bad?
    Community Answer
    Community Answer
    If the resistance is higher than calculated or it's infinite (so the circuit is open), then you can assume that the heating element has gone bad. Same thing applies to the switch - if after setting the switch to the "on" position, the resistance is infinite, then it means that the switch doesn't close the circuit and it's broken.
  • Question
    What would cause a microwave to not heat up food?
    Debra Bish
    Debra Bish
    Community Answer
    If your microwave oven quits heating food, it's time for a new microwave oven. There is usually not much else one can do when this happens.
  • Question
    You are using the formulas for D/C power, but the voltage you are calculating with is Peak to Peak A/C. Don't I need to convert it to Vrms first?
    James Jemima
    James Jemima
    Community Answer
    In the USA for example, your everyday, normal household AC Voltage does in fact equal Vrms=120V, and of course 2-phase AV Vrms=240V. The numerical conversion is already built into the standard. You can verify this easily as almost every modern multi-meter reports Vrms, as that is the more useful and informative value as opposed to peak values.

Warnings

  • Take care when dealing with electricity. If you're not confident in your ability to work with electricity then don’t do it. Ask some one who is, such as an electrician or an electrical engineer.
    Thanks!
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Things You'll Need

  • Multimeter or Ohmmeter and Voltmeter

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References

  1. ↑ https://www.electronics-tutorials.ws/resistor/res_7.html
  2. ↑ https://www.youtube.com/watch?v=CshL-6Hp2AE
  3. ↑ https://www.youtube.com/watch?v=CshL-6Hp2AE
  4. ↑ https://www.todayshomeowner.com/video/how-to-drain-a-water-heater/

About This Article

wikiHow is a “wiki,” similar to Wikipedia, which means that many of our articles are co-written by multiple authors. To create this article, 27 people, some anonymous, worked to edit and improve it over time. This article has been viewed 326,807 times.
234 votes - 86%
Co-authors: 27
Updated: October 21, 2021
Views: 326,807
Categories: Heating Systems
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