Most Miami homes and nearly every condo heat water with electricity, usually in a tank in the garage, a utility closet or a closet off the kitchen. A tank water heater is a simple appliance: a 240-volt circuit, two heating elements, two thermostats and a safety cutoff. When something goes wrong, it shows up either as a tripped breaker in the panel or as no hot water with the breaker still on. Those are different problems, and telling them apart is the first step.
Two different shutoffs
- The breaker in the panel. A double breaker, usually labeled water heater or WH. It trips when current goes where it should not: a short, a ground fault or an overload.
- The high-limit cutoff on the heater. Most electric tanks have a safety switch, often with a red reset button, behind the upper access cover. It cuts power when the water gets too hot. When it trips, the breaker stays on and you simply run out of hot water.
So if the breaker is tripped, the problem is electrical: in the heater's elements or wiring, or in the circuit. If the breaker is on and the water is cold, the heater's own cutoff or an element is the more likely cause.
Why the breaker trips
- A failed heating element. The most common cause. An element is a coil inside a metal sheath that sits in the water. When the sheath cracks, water reaches the coil and current leaks to the tank, which trips the breaker.
- An element that ran dry. If the tank was drained, or was not completely full when the power came on, an element can burn out within moments. Breakers that trip right after a tank flush or a replacement often trace back to this.
- A burned connection. The wires from the circuit meet the heater in a small box on top of the tank. A loose connection there heats up under the heater's steady load and can melt insulation until it shorts.
- Water on the wiring. A leaking valve, fitting or tank dripping onto the connection box or into the element compartments.
- A worn breaker. Water heater breakers carry a heavy load for hours a day. One that has overheated or loosened at the panel can trip below its rating.
If water is leaking around the heater, turn its breaker off and leave it off. Water and a 240-volt circuit are a bad combination, and the leak needs a plumber regardless.
About the red reset button
The high-limit switch trips for a reason: usually a thermostat that stuck on, or an element that has shorted to the tank and keeps heating. Pressing reset without fixing that only brings the problem back. The button sits behind a cover over live 240-volt terminals, so the breaker must be off before the cover comes off, and your heater's manual describes the steps. If you are not comfortable doing that, or the reset trips again, leave it for whoever services the heater.
Electric tankless heaters need big circuits
Whole-house electric tankless heaters heat water as it flows, so they draw a very large current while a tap is open. The Department of Energy's Building America guide to transitioning to a tankless water heater notes that most electric tankless units need 208 or 240 volts and require 50 to 200 amps depending on the size of the unit. That is often several large circuits, and in an older home with a smaller service it can be more than the panel can supply. If a tankless heater trips its breakers when two showers run, or since the day it went in, the circuits, wire size and connections need checking against the installation guide. Before buying one, have the panel and service looked at; see 100 vs 200 amp service, dedicated circuits and panel upgrades.
What you can safely check
- Reset the breaker once. If it trips again right away, leave it off. See breakers that trip again on reset.
- Note when it trips: immediately, when the heater starts heating, or only after a lot of hot water has been used.
- Look for water on the floor, the top of the tank and around the access covers.
- Note anything recent: a flush, a new heater, a plumbing repair, a storm.
- Do not open the connection box on top of the tank or the panel.
After flooding, do not turn a water heater back on until it has been checked; our post-storm checklist explains why.
Who fixes which part
Elements and thermostats are electrical parts inside a plumbing appliance, so depending on who you call, a plumber, a water heater service company or an electrician may replace them. The tank, valves and leaks are a plumber's work. The circuit is an electrician's: the breaker, the wire, the disconnect if there is one, and the connection at the heater. Our guide to appliance tech, HVAC tech or electrician covers how to decide when you are not sure.
What we check
We test the circuit and the breaker, check the connection at the heater for heat damage, and test the elements for a short to the tank. That tells us whether the fault is in the heater or the wiring feeding it. If the wiring is damaged we repair it; if the circuit is undersized for the heater, we tell you what it needs. See circuit breaker repair.
Questions people ask
Why did the breaker trip right after the tank was flushed?
Most often an element was powered before the tank refilled completely and burned out. The element needs replacing, and the breaker should hold once it is.
Is it safe to leave the water heater breaker off?
Yes. The tank keeps water warm for a while, and nothing is harmed by leaving it off until it is repaired.
Can I use a bigger breaker?
No. The breaker size is set by the wire and the heater's label. A bigger one stops protecting the wire.
Need it looked at?
KRW Electric (EC13012832) troubleshoots and repairs water heater circuits that keep tripping in Pinecrest, Coconut Grove, South Miami and Miami Beach, with same-day service when scheduling permits. Call (305) 359-7312 and tell us what you are seeing. We will ask a few questions, tell you whether it sounds urgent, and give you the earliest time we have. Our before you call checklist covers what to have ready, and what happens on a repair visit explains the rest.
Reviewed by Kyle White, KRW Electric Company LLC — licensed electrical contractor EC13012832.
