Why a Water Heater Keeps Tripping the Breaker

Electric water heaters have dedicated circuits. This means there is nothing else connected to their circuit breakers. Sometimes the breakers can trip for seemingly no apparent reason. They can trip randomly, and then you can reset them and use the water heater for a while until it trips again. Other times they can trip and you won’t able to reset them.

Circuit breakers trip for a reason and it can potentially be a dangerous situation that needs immediate attention. Even if they only trip every now and then, there is something causing it. In order to avoid damaging your home and risking an electrical fire, it’s best to troubleshoot the problem.

In this article, we’ll take a look at what causes the water heater breaker to keep tripping and see what you can do about it.

What Should You Do?

First, do not continue flipping the breaker back on if it keeps tripping. If you do this, you run the risk of the wiring overheating and potentially starting an electrical fire. This can also wear out your circuit breaker and damage your water heater further.

The breaker is tripping because of a problem and that problem won’t go away on its own. Leave the breaker off and troubleshoot the problem immediately. Fortunately, troubleshooting a tripping water heater breaker isn’t that difficult. Following a few troubleshooting steps can help you find the problem. Here are the most common causes and fixes.

Bad Thermostat

Water heaters have a limit switch that keeps the water from exceeding 180°. When the water reaches 180° the limit switch (a little red reset button on the water heater) trips. This helps protect you from getting burned or scalded by the excessively hot water.

The most likely cause of the limit switch tripping is a bad thermostat. Water heaters with two elements have two thermostats: one for each element. The thermostats communicate with each other to ensure that only one element is being heated at a time. When they go bad they sometimes get stuck in the on position. This causes the heating element, or both heating elements, to remain on and continuously heat the water.

If the water heater has two elements, as most electric water heaters do, both elements remaining on at the same time can overload the circuit. The circuit will then draw too much current and get hot, causing the breaker in the breaker box to trip.

The thermostats can be tested with a multimeter. Make sure the power to the water heater is off. Disconnect the wires from the thermostat (mark them so you know where they connect) and then check the thermostat for resistance. It should have no ohms (it should show an open, or infinity) for a normally open (NO) thermostat and close to 0 ohms (it should have continuity, but it might have around 0.5 ohms including the meter and leads) for a normally closed (NC) thermostat.

Bad thermostats will need to be replaced. Many recommend replacing the heating elements at the same time as replacing the thermostats.

Bad Heating Element

As we’ve discussed, most electric water heaters have upper and lower heating elements. They work together to keep the water hot. This is especially important in larger tanks. Usually, when a heating element fails it stops heating and water is colder than normal. If this is the case, then the heating element is open internally and won’t cause any damage. Unfortunately, this isn’t always the case.

Sometimes, the casing on the heating element can split. This exposes the electrical portion of the element to the water in the tank, causing the element to short the circuit and trip the limit switch or breaker.

An element can also short. This causes the element to remain on, continuously heating the water. This will trip the limit switch when the water gets too hot.

A heating element can be tested with a multimeter. With the breaker to the water heater off, remove the wires from the element. Test across the points where the wires attach to the element. You should get these resistances:

  • 3,500-watt element = 16 ohms
  • 4,500-watt element = between 12 and 13 ohms
  • 5,500-watt element = between 10 and 11 ohms

If you get a different resistance then you should replace the heating element.

Water Leak

If the water heater is leaking, such as through a failing gasket for the heating element, it could come in contact with electrical components and trip the breaker. This is dangerous and could cause a serious electrical shock.

If the breaker is not already tripped, then turn off the breaker immediately and repair the water leak.

Internal Wiring

There could be an internal wiring issue causing the breaker to trip. With the power off, open the panel to see where the water heater is attached to the house’s wiring. Look for burned connections, damaged, wire, or anywhere electricity has arced. If there has been an arc you’ll probably smell smoke.

Replace any damaged wiring and connectors before using the water heater.

Wiring or Electrical Problem

If the problem isn’t with the thermostat, heating element, a water leak, or internal wiring, chances are the problem lies outside of the water heater. It could be a loose or bad wire, a bad connection in the electrical panel, or a worn-out breaker.

Check the wiring on the line for broken or loose wires. If the breaker trips and there are no problems on the line, then you’ll need to replace the breaker. If the problem is the breaker, make sure to replace it with the same rating. Do not replace it with a higher-rated breaker, as this will allow more current to flow through the circuit and overheat.

Conclusion

It’s no fun when a water heater keeps tripping the breaker. It can also be dangerous and cause serious damage to you or your home. Fortunately, it isn’t that difficult to track down the problem. The most likely culprit is a bad thermostat followed by a heating element, but it could be a bad breaker or other wiring issues.

Remember – safety first. Always stay safe when working on electrical issues. Never work with electrical lines if you’re not experienced.

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