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How to test water heater element

Buy multimeter
Install battery.
Setting 1: Rotate dial to 240-250Vac to test for electricity.
Setting 2: Rotate dial to Ohms to test element as shown on this page.
(upside down horseshoe symbol is ohms)
1) Use multimeter to test element
2) Do not drain water heater
3) Power is OFF during this test.

How to troubleshoot electric water heater

See cold resistance ohm chart
Ohms is resistance
​Volts squared divided by watts = ohms
​However, there are a wide range of results and element can still be good.
​Applies to cold element, and not hot
Cold resistance: measuring ohms across both screw when no wires are attached to element and element is not heated.
Hot water in tank raises resistance on element ... ohms is a measure of resistance.
Let the element cool before doing ohm test across both screws so you are measuring cold resistance.
Hot wires have more resistance than cold wires... including resistance elements ... and the ohm meter measures resistance.
Watts and volts are printed on end of each element.
220 Volt circuit breaker Turn off circuit breaker
Turn off 30 amp double breaker to 240Volt heater
Turn off 20 Amp single breaker to 110 Volt heater
water heater element
Test for voltage using non-contact voltage tester.
Advantage of non-contact voltage tester ease and is safety since wire nuts are not removed.
Never assume power is OFF.
Touch end of tester to each black, white, and red wire. Press button. If tester flashes repeatedly like alarm, then voltage is present. if tester flashes once, then that says no voltage is present.

Non-contact voltage tester
Test water heater
Larger image
Test for voltage using voltage tester.
Remove wire nuts.
Applies to120V and 240V.
Test Black to Ground, test Black to White, test White to Ground. If tester light comes on with any test, electricity is present.

See basic water heater circuit
water heater thermostats Open panels on side of water heater
Do not drain water heater to test elements.
Remove insulation

Older water heaters have fiberglass insulation covering element and thermostat.
Newer water heaters have tight-fitting foam insulation.
Newest tanks have thicker foam insulation.
Foam insulation is not easy to work around. You may need to cut back the foam to work on parts. Remove as much foam as needed to access parts.

Insulation must be put back when finished.
When finished, thermostats and elements must be covered by insulation again or thermostats become exposed to cool air and will misread tank temperature.
Always best to put safety cover back into place when finished.
Remove plastic safety covers that sits over element.
Pull off tab at top then poll off or unhook sides
Replace covers when finished.

Upper element terminal protector
Lower element terminal protector
Water heater insulation
Larger image
Which element do you test?
If water heater makes some hot water, then lower element is suspect.
If upper element is burned out, water heater will have no hot water. Test both elements.
If water heater is tripping circuit breaker, then test both elements and look for burned and melted wire.

What to do if melted/burned wire is found
Water heater is tripping breaker
Troubleshoot electric water heater
How water heater works
How to wire thermostats
Test electricity to water heater
Element burns out
Tank must be full of water or elements burn out ...; called Dry Fire.
If you replaced either element and water heater is still not working ... test upper element
remove wires from elelment Take wires off element

Use nose and eyes to inspect for burned/ melted parts and wires.
If wires are burned/ melted then replace part and test wire for continuity.

Test water heater wires

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water heater element Bolt-in and screw-type elements
Water heater elements
Low density element
Test element
Set multimeter to read ohms

Good element passes 3 tests:
Test 1: Element shows correct ohm reading
Test 2: No reading on multimeter
Test 3: No reading on multimeter

Rotate dial to Ohms to test element
Ohms is upside down horseshoe symbol

Water heater element
Larger image
Watt and Volt rating printed on end of each element
Important: Ohm test varies by watt and volt rating of each element.

See ohm chart
test element Test 1: Test across both screws
Test across both element screws and resistance should read about 12.8 Ohms for 240-Volt 4500-Watt element. For 30 gallon tank with 3500-Watt elements, reading is about 16 Ohms.
Open reading means element is bad. No reading means element is bad.

Check watt and volt rating printed on each element
Applies to COLD element. Water heater with warm water will change reading.
Element wattage      volts                     ohms
3500 watt                 240                       16
4500 watt                 240                       12-13
5500 watt                 240                       10-11
Ranges can vary widely, even with good multimeter.

'Volts squared' divided by watts = ohms Volts x volts is 'volts squared' 240 volts x 240 volts = 57,600 volts squared 57,600 volts squared divided by 4500 watt = 12.8 ohms
See ohm chart
test element 2 Test 2: Test screws to metal shell
Test each screw to bare metal part of water heater.
Test both screws.
If multimeter reads any Ohms at all, or if needle moves even tiny bit, then element is shorted and needs replacement see how
Test element 3 Test 3: Test screw to element
Test each screw to metal base of element.
If multimeter reads any Ohms at all, or if needle moves even tiny bit, then element is shorted and needs replacement
- Results -
If element passes all 3 tests
Elements are good and passes all 3 tests
Double-check results before putting wires back on elements.
If elements burn out frequently, then install lower wattage element.

Elements passes all 3 test but water heater still not working
Push breaker fully off and then fully on
Tank heats 21-40 gallons per hour
Troubleshoot walk-thru
Melted wire Element has burned wire

Replace element
Test wire for continuity
Element is bad
How to replace element
Full efficiency can be restored to electric heater

Water heater must be full to loosen element, but must be empty before element is removed
Water heater elements
Low density element
Element wrench
Leave water heater full of water to loosen element
Then drain water heater and remove element
Water heater element socket 1-1/2"
Camco heavy duty element socket
Marathon elements are 1-7/8"
Buy from my links
  $25 - $47
Ultra low watt density
5 year warranty
Ultra Low Watt Density/ ripple
Hard water element
Resists high mineral count
Minimum 15" diameter tank
Buy: 240 volt from my associate links:
4500 watt
4500 watt 13" diameter
5500 watt
Camco elements
$13 - $26
Ultra low watt density
5 year warranty
Ultra Low Watt Density/ foldback
Hard water element
Resists high mineral count
Check minimum tank diameter
Fits any tank above minimum dia
Buy: 120 volt
1500 watt 120 volt 8" minimum
Buy: 240 volt:
2500 watt 
3500 watt
4500 watt
5500 watt
Low watt density
Low watt density
Rheem/ no extended warranty
Low Watt Density/ foldback
Minimum 14" diameter tank
Buy:< 240 volt/ copper non- resistorized:
4500 watt copper 240 volt

Buy: 240 volt/ stainless steel non- resistorized:
4500 non-resistorized Amazon
5500 non-resistorized Amazon

Rheem elements
$10 - $16

Low watt density
Camco/ no extended warranty
Low Watt Density/ foldback

Check minimum tank diameter
Fits any tank above minimum dia
Buy: 240 volt:
2500 watt
3500 watt
4500 watt
4500 watt 12 pack
5500 watt

6000 watt
$10 - $12
Low watt density
Camco/ no extended warranty/
High Watt Density
Standard on all new water heater
Can use foldback as replacement
Match volts and watts
Buy: 240 volt
1500 watt
2000 watt 12 pack
2500 watt
3000 watt
3500 watt
3800 watt
4000 watt
4500 watt
4500 watt 12 pack

Buy: 120 volt copper:
2000 watt 120 volt

Buy: 240 volt copper:
1500 watt 240 volt
2000 watt 240 volt
3000 watt 240 volt
3000 watt 240 volt
5500 watt 240 volt
Camco element socket

Use 1-1/2" socket to remove elements

Camco element socket
Tekton water heater socket
Deep impact socket

16" breaker bar fits impact socket

Ordinary Residential element wrench

Today's hex-head elements have rounded corners, and thinner profile. Making it difficult to hold wrench on element while turning.
Socket is easier to use than ordinary element wrench.
Use weight of water: Loosen element while tank is full of water. Then drain tank before unscrewing element.
High density element
Low density element
Screw-in elements
Elements burn out frequently: install lower wattage element, or install low watt density element
Causes include:
a) Sediment in bottom of tank   How to replace element and clean out sediment.
b) Very hard water. Install softener. Read about softener and anode depletion
c) Watt density of element too high. Change element. Install element with less than 3800 watt See image  Read pdf
d) Aggressive high pH water. Test water.
e) Loose wire on element. Open covers and inspect all wires for loose connections and signs of burning.
How to replace elements
Water heater formulas and terminology pdf

Water heater elements
Low density element
480 volt element
Larger image
Volts and watts are printed on end of each element
Volts and watts are printed on end of each element
480 volt 4000 watt
415 volt 3000 watt
When voltage drops, the element wattage also drops

Typically 480 volt is common on 3-phase non-balanced commercial water heaters. The non-balanced 3-phase heater can be converted to single phase but attention must be paid to the element voltage and wattage
How to figure resistive wattage by volts
Ohm's laws says: Volts squared  watts = ohms  Resources: See chart   How to test element

Each element has volt and watt rating printed on end of element
If element is rated 4500 watts @ 240 volts.... then volts squared (57600) 4500 watts = 12.8 ohms
So 12.8 is the ohm rating for the element, no matter what voltage is applied

But what happens when voltage is reduced on the same element?? For example voltage is reduced to 208 volts instead of 240 volts.
Then 208 volts squared (43264)  12.8 ohms = 3380 watts... and the element does not burn as hot

What happens when voltage is reduced to 120 volts on same element?
Then 120 volts squared (14400) 12.8 ohm = 1125 watts and heating is reduced to 1/4 the original output

What happens when voltage is reduced on 480 volt, 4000 watt element?
480 Volts squared (230400) 4000 watts = 57.6 ohms/ and 57.6 is the ohm rating for element no matter what voltage.
So when voltage is reduced to 415 volts:
415 volts squared (172225) 57.6 ohm = 2990 watts (or 3000 watts as shown in photo)

What about increasing voltage instead of lowering voltage?
What happens when 480 volts is connected to element that is rated for 4500 watts and 240 volts? POW ! element burns out
480 volts squared (230400)  12.8 ohm element = 18,000 watts or 4 times the rating... and the element will burn out immediately

:What happens when 240 volts is connected to element that is rated for 2000 watts and 120 volt? POW again
120 Volt squared (14400) 2000 watts = 7.2 ohm
240 volts squared (43264) 7.2 ohm element = 6000 watts running through a 2000 watt element causing it to burn out

So buy element that is rated for the voltage  Resource Elements and element replacement
3-phase non-balanced / and conversion to single phase
remove old water heater element Element will not come out
How to remove rusted element
Drill, tap and use bolts and wrench to remove.
Drain water heater before drilling into element

Prevent rusted water heater.
Anode rod is necessary so tank will not rust.
Anode rod depletes and should be inspected 1-3 years with water softener, and 2-5 years otherwise.

Loosen anode rod before draining tank so weight of water helps hold tank steady
How to replace anode rod
clogged water heater Water heater will not drain
Do not drain water heater to test element.
Water heater is drained only when replacing element

Water heater will not drain
Use household water pressure and washing-machine hose to flush open water heater for 5-10 seconds
Water heater cover
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Re-install insulation over thermostat and element
 Caution: Insulation and cover must be re-installed or thermostat is exposed to cooler air and will misread tank temperature.

How to replace water heater thermostat
Shorted element
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ECO reset button keeps tripping
or circuit breaker keeps tripping: element shorted to ground across steel tank
What happens:
- Illustration shows why element-test requires testing between element screws and steel tank
- 240Volt water heaters have 2 Hot wires. Each hot wire is called a leg. Each leg is 120Volts with 240Volt potential when both legs are connected together. Difference between 120Volts and 240V
- Thermostats turn off one leg in the 240Volt circuit.
- When thermostat turns ON, that event connects the second leg to the first leg, and element turns ON.

- In some cases, the element can crack or short. In most cases, the short will trip circuit breaker.
- If the crack or short is far enough along in the element, the resistance will not cause breaker to trip. The short travels across steel tank hull to the ground wire at top of tank.
- The ground wire will complete 120Volt circuit. Elements will heat up using 240Volts or 120Volts. Element continues heating, and will not turn off. This causes runaway heating, and TP valve will release water or ECO reset will trip.
How to convert water heater to 120volts
Breaker keeps tripping
Read more:
Circuit breaker keeps tripping
New water heater not working
Maintain water heater pays $10 per month
How to maintain water heater
1)  Read about anode rods
 2)  Read about stray current corrosion
3)  How to clean sediment out water heater
4) How to flush water heater/ steps
5)  9 ways to save with water heater

Flush each 6 months
Inspect for leaks each 6 months
Check and replace anode rod each 1-3 years
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