Water Heater Element: How to Test One and Change It
By Ray Bennett · Updated 18 September 2026 · 6 min read · Checked against element ratings and maker manuals 
Switch the power off, then read across the element's two screws with a meter set to ohms. Ten to sixteen ohms means it is alive. OL or nothing at all means it has burned through, and any reading between a screw and the tank means it has shorted.
Every electric tank heater has two of these: one near the top, one near the bottom. They are simple parts, about twelve dollars, and they are the most common reason an electric heater goes cold.
The test takes five minutes and needs one tool. The part that takes the time is draining the tank, not changing the element.
Turn the power off, and prove it is off
Find the breaker marked water heater and switch it off. It is a double breaker, because the heater runs on 240 volts.
Then take the upper access panel off the side of the tank, fold the insulation back, and hold a non-contact voltage tester against the wires behind the plastic cover. No beep, no light, no power. If you only have a multimeter, set it to volts and put the probes on the two screws the wires land on. Zero is what you want to see.
Which element has failed, from the symptom alone
The two elements do different jobs, so the way the hot water goes wrong tells you which one to look at first.
No hot water at all. Almost always the upper element, the upper thermostat, or the little red reset button between them. The upper thermostat controls everything, so when it goes, nothing heats.
Hot water, but it runs out in a few minutes. The lower element. The top of the tank is still heating and the bottom is not, so you get one short shower out of it and then cold.
Water is lukewarm and never gets properly hot. Usually the lower element too, sometimes a thermostat set low by somebody else in the house.
The breaker trips the moment you switch it back on. An element that has shorted to the tank. The ohm test below finds it.
Test it with a multimeter
Any cheap meter does this. You need the ohms setting, the one marked with the horseshoe symbol.
Take one wire off the element
With the power off, undo one of the two screws on the face of the element and lift that wire clear. If you leave both wires on, you are measuring the whole circuit and the reading will lie to you.
Two minutes, no parts needed.
Read across the two screws
Put one probe on each screw. A good element gives you a steady number somewhere between 10 and 16 ohms, depending on its wattage. The table below says which number is right for yours.
If the meter shows OL, or 1 on the left of the screen, or nothing at all, the element is burned through. That is the whole diagnosis.
A live element reads 10 to 16 ohms.
Read from one screw to the tank
Leave one probe on a screw and touch the other to the bare metal of the tank or to the element’s mounting flange. A good element reads nothing at all, an open circuit.
If you get any number here, water has got inside the element and it is leaking current to the tank. It has to come out even if it still heats.
Any reading here means a shorted element, and that is what trips the breaker.
What the number on your meter should be
The wattage is stamped on the face of the element, next to the voltage. The resistance follows from it, so you can check your own reading against the right figure rather than guessing.
| Element | What the meter should show |
|---|---|
| 3,500 W at 240 V | about 16 ohms |
| 4,500 W at 240 V | about 13 ohms |
| 5,500 W at 240 V | about 10 ohms |
| Any of them, burned out | OL, or no reading |
A few ohms either side of those numbers is normal and not a fault. Half the number, or double it, is not.
Changing the element
The element screws into the tank, so the water has to come out before it can. Budget an hour, and most of that is the tank draining.
1. Shut the cold water off. The valve on the pipe going into the top of the heater. Then open a hot tap somewhere in the house and leave it open, or the tank will not drain.
2. Drain it. Garden hose on the drain valve at the bottom, other end outside or into a floor drain. A fifty gallon tank takes twenty to thirty minutes. If the flow slows to a trickle, sediment is blocking the valve, and poking a screwdriver into it usually clears it.
3. Take the old one out. Most are screw-in and need an element wrench, a cheap socket with a bar through it. Some are flange type, held by four bolts. Wires off first, then unscrew.
4. Fit the new one with its new gasket. The gasket comes with the element. Seat it dry, no sealant, and tighten it firmly by hand with the wrench. Match the wattage and voltage to the old one exactly. A higher wattage element on wiring that was never sized for it is a fire, not an upgrade.
5. Fill the tank completely. Close the drain, open the cold water, and leave that hot tap running until the water comes out steady with no spitting. That is the air leaving the tank.
6. Only then switch the power back on. An element fires at full power the second it gets electricity, and a dry element burns out in about ten seconds. This is how most new elements die.
Hot water takes twenty to forty minutes from cold on a 4,500 watt element.
Why it burned out
Elements do not wear out from being used. They fail for three reasons, and two of them will happen again if nothing changes.
Sediment. Minerals settle on the bottom of the tank and bury the lower element, so it cooks inside a crust instead of heating water. Draining a few gallons off the bottom twice a year is the whole prevention.
Dry firing. Power on before the tank was full. Ten seconds is enough.
Hard water scale. Scale builds on the element itself until it cracks. Common in hard water areas, and the reason some people fit a low watt density element, which spreads the same heat over a longer element and scales more slowly.
Questions people ask
My heater is gas. Where is the element?
There isn’t one. A gas heater heats with a burner underneath the tank, and the parts that fail there are the thermocouple, the pilot and the gas control. Nothing in this page applies to it.
Can I test the element without draining the tank?
Yes. The test is done with the element still in the tank, through the access panel. You only drain it if it turns out to be dead.
Should I change both elements at once?
If the heater is more than about six years old, yes. They are twelve dollars each and the tank is already drained, which is the part that costs you the afternoon.
The red reset button keeps popping. Is that the element?
Often. That button is a safety cutout on the upper thermostat, and a shorted element or a stuck thermostat is what keeps tripping it. Do the third test above before you buy a thermostat.
How long should a new element last?
Six to ten years in normal water, less in hard water. If a new one fails inside a year, the water or the sediment is the problem, not the part.
