How to Test for a Bad Electric Water Heater Heating Element

Electric Water heater elements: how to inspect, test, adjust, repair a water heater element
- Ohm chart of measured resistance of electric water heater heating elements for common rated wattages
- How to find & replace an electric water heater heating element that is not working
- How to test and repair an electric hot water heater that is producing only tepid hot water or not enough hot water
- Test procedures for electric water heater heating elements
- How to replace the heating element on an electric water heater
DMM Digital Multimeter, How to Use
ELECTRIC WATER HEATERS
Questions & Answers about how to test the heating elements on an electric water heater
References

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Electric water heater element test procedure: this article describes how to test electric hot water heater heating elements, what readings to expect if using an ohmmeter. This article describes the steps in testing electric hot water heater heating elements, followed by a guide to replacing a bad heating element (Electric Water Heater Element Replacement). This series of articles describes how to inspect, operate, diagnose, and repair electric hot water heaters. The articles at this website will answer most questions about electrical water heaters as well as many other building plumbing system inspection or defect topics. Reproduction of this web page electronically at other websites is prohibited. If you cannot find information you need here or if you have comments, questions, suggestions for inspecting and diagnosing water heaters Contact Us

How to Test Electric Water Heater Heating Elements

Operating Sequence of Electric Water Heater Elements upper and lower heating elements

Note: Once you have diagnosed which heating element is bad, also see Electric Water Heater Element Replacement.

Because the electric water heater might be failing to work due to loss of electrical power to the unit, or because of a malfunctioning high-temperature cutoff switch, you should also see the test steps at How To Test High Temperature Cutoff Switch

Electric water heater drawing (left) showing the sequencing procedure for electric water heater elements is provided courtesy Carson Dunlop Associates, used with permission

Electric water heaters have two heating elements - thick metal loops that get hot when electricity flows through them, similar to the burner on an electric range.

The lower heating element heats cold water as it enters the hot water tank. (Incoming cold water is delivered to the bottom of the tank through the dip tube.)

This element works the hardest, is on the most, and so often is the first to burn out. The upper heating element acts as a "booster" to heat water when there is a high demand. This element heats only the water in the upper portion of the hot water tank.

As we introduced earlier, if there is some hot water but it is limited in quantity or temperature, just one of the heating elements may have failed.

Scale coating a water heater element can also reduce the quantity of hot water (or cause heating element failure) - a topic we review in more detail at WATER HEATER SCALE - De-Liming Procedure and WATER HEATER SCALE PREVENTION and at WATER HEATER NOISES.

If the electric water heater produces the same old quantity of hot water, but water is only tepid rather than hot, we suspect that the top water heater element has burned out. The bottom element is heating the entire tank but it is not capable of heating the water to the same high temperature as if both elements were working. Long tepid shower - bad top water heater element.

If the electric water heater produces the same old hot water temperature, but the quantity seems drastically reduced, we suspect that the bottom water heater element has burned out. Only the water in the top of the tank is being heated. Cold water enters and remains at the bottom of the water heater. So our hot water is plenty hot but we run out in just a few minutes. Short hot shower - bad bottom water heater element.

As we're about to show in detail, one can test a water heater heating element by a simple procedure using a continuity tester or a volt-ohm meter- a VOM. For details on how to use electrical test equipment see Using DMMs & VOMs Safely and see VOLTAGE DETECTION & MEASUREMENT. General electrical inspection safety advice is at SAFETY for ELECTRICAL INSPECTORS.

Steps in Testing an Electric Water Heater Heating Element - Good Method

Turn off electrical power to the water heater - you should have done this earlier if you read the instructions above. Turn off power at the water heater circuit at the main electrical panel.
The water in the heater should be lukewarm or colder. If the water heater is hot, run hot water in the building (with the water heater electrical power OFF) until water flows lukewarm or colder.
Disconnect the electrical wires at the heating element terminals. (This is so whether testing upper or lower heating element).
Test for current flow: Use a VOM, DMM, or Ohmmeter or multimeter set to read "resistance" or "ohms" as follows: connect one alligator clip or touch one probe of the VOM to each terminal on the water heater element.

One probe touches one terminal, the other probe touches the other terminal. If the Ohmmeter needle doesn't move (or no reading is given on the DMM) then the electric water heater heating element is defective and needs to be replaced.

If the ohmmeter needle moves or you get some Ohm reading (other than infinity) then the heating element is OK and you are ready to test the other heating element on the heater. In sum, if there is "continuity" through the heating element it is working. If there is no continuity (no electrical current can flow) then the element has failed.

Testing an Electric Water Heating Element for a Short Circuit - Crude Method & OHM Table for Water Heater Elements

We do not usually make this test but we include it here as it appears in some diagnostic procedures for electric water heaters. The water heater element OHMS chart (left, courtesy A.O. Smith) describes the actual ohm reading you'd expect if testing a factory OEM heater element of the wattage shown.

Even without that level of detail there is a simple test you can perform to see if an electric water heater heating element is in good working order:

Turn off electrical power to the water heater - you should have done this earlier if you read the instructions above. Turn off power at the water heater circuit at the main electrical panel.
Remove the access panel cover and insulation from the top or bottom water heater element (described above)
Connect the alligator clip or test terminal of your continuity tester to one terminal of the heating element. That's the wire and screw right on the heating element itself.
Connect the other probe of the continuity tester (or VOM) to a bolt or bracket that holds the heating element in position.
If the test light goes on, the buzzer sounds, or your VOM (set to Ohms) indicates continuity, there is a short circuit in the heating element and it needs to be replaced.

Causes of Heating Element Failure on Electric Water Heaters

Besides old age and high usage, if your building water supply provides hard water (high in mineral content), scale build-up on water heater elements can lead to their demise.

See WATER HEATER NOISES for details about removing scale from a water heater.

See Electric Water Heater Element Replacement for the steps in replacing a bad electric water heater heating element.

Frequently Asked Questions (FAQs) about how to test for a bad electric water heater element

Question: lightning strike damaged the water heater wiring/element

I just replaced the lower element today. The test by continuity to both screws was ok but from one (1) screw to ground was not. Bad element; short circuit. Lightning had struck a large pine tree in the front about 40 yards from heater two days ago. All breakers did their job well by shutting down the power to heater and the breaker in heater shut down also. - Lloyd 3/23/12

Reply:

Tanks Lloyd, that's helpful details.

Question: Keith thinks you cannot use a VOM or DMM to test water heater elements by checking resistance

You cannot ohm the elements, since if open the water will show continuity.
A much simpler, faster , more accurate method is check for voltage 1st, and see if any amp draws going on! if not its bad! - Keith Grayson 12/10/11

Reply:

I don't think you've got it correct, Keith, and too, it's safer to test water heater elements with electricity to the unit OFF.

The standard test of the condition of an electric water heater element is the resistance test described in the article above.

If the heating element is dead shorted out it will show continuity - that is not an OPEN circuit, it's a CLOSED one. Continuity in this case means close to zero resistance - which is not normal for a water heating element and thus would indicate trouble.

An OPEN circuit is one that is not continuous - so we would see infinite resistance. This is a more common mode of electric water heater element - the element just burns up and becomes an open circuit. Of course to avoid confusion these tests are done with electrical wires to the heating elemen t removed.

Take a look at DMM Digital Multimeter, How to Use for a nice article on how to hook up and use a digital multimeter or a VOM to check for voltage or for circuit continuity or for resistance.

Question: GE water heater flooded by Hurricane Sandy - can we just turn it back on to see if it works?

Our 50 gallon got flooded by about 2 feet of water. The lower elements got wet. is it safe to flip back on the breaker to see if by chance the heater is still working? - GE Hot water heater flooded 11/19/2012

GE hot water heater is electric, with the power coming in from the top of the tank.

Reply:

GE water heater,

Before turning on electricity electrical components need to be dried and inspected, lest you otherwise cause a short circuit that could be dangerous.

Worse, if floodwaters submerging the heater were unsanitary, say with sewage contaminants, the heater insulation icontaminated as well.

With power OFF to the heater so you don't get electrocuted, you or your electrician can remove the access covers to expose, dry, and inspect the wiring and connections. At the very least, start there.

For details on how to get a flooded water heater back into service - if it can be re-used, see FLOODED WATER HEATER REPAIR

It it were mine, I'd replace the unit.

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How to Test Electric Water Heater Heating Elements

Operating Sequence of Electric Water Heater Elements upper and lower heating elements

Steps in Testing an Electric Water Heater Heating Element - Good Method

Testing an Electric Water Heating Element for a Short Circuit - Crude Method & OHM Table for Water Heater Elements

Causes of Heating Element Failure on Electric Water Heaters

Frequently Asked Questions (FAQs) about how to test for a bad electric water heater element

Question: lightning strike damaged the water heater wiring/element

Reply:

Question: Keith thinks you cannot use a VOM or DMM to test water heater elements by checking resistance

Reply:

Question: GE water heater flooded by Hurricane Sandy - can we just turn it back on to see if it works?

Reply:

Ask a Question or Search InspectApedia

Technical Reviewers & References

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair