Most of us use a lot of electricity and, nationally, the usage increases a few percent each year in spite of energy-efficient lightbulbs and appliances. Americans just keep getting more gadgets and appliances. Much has been written about ways to cut back on the number of kilowatt-hours you consume each month, and we won’t go into that subject here. But what about when your bill spikes up abruptly in a single month?

    Extremely hot or cold weather that makes a heat pump air conditioner work longer hours will raise your bill, and so will a swarm of houseguests that use plenty of hot water. But if there is no event you can think of that would have caused the bill to shoot up, then you need to consider other possibilities:

1) Hot water leakage - The first way that you could have leaking hot water is at the TPR (Temperature and Pressure Release) valve at your electric water heater. It is a safety valve that is on the top, or on the side near the top, of the water heater and designed to open if the thermostat fails to shut off the heating element and the tank overheats. If left unchecked, the tank will eventually explode violently, so the valve opens when the temperature of approaches 200º F to release the pressure and avoid a disaster.


  Unfortunately, some TPR valves begin leaking as they get older. The piping from the valve may extend to near the floor next to the water heater, where it is very easy to observe any leakage as soon as it starts. But, in many homes, the pipe terminates just above the ground at an outside wall, pointing downward, and it is often obscured by landscaping growing in front of it. The photo below shows an example of a typical TPR valve pipe termination.


    In some mobile homes and older homes with elevated wood floors, the TPR terminates under the floor and is not visible without entering the crawl space. Here’s an example of a long-term leak under a mobile home. 

    Since TPR leakage is equivalent to leaving a hot water faucet running 24-hours a day, it will definitely run up your electric bill. So check the termination of the TPR piping for leakage. Although, the termination is required to be visible, in some older houses and mobile homes that have elevated floors it is hidden in the crawl space under the home. In that case, you can wrap your hand around the TPR  pipe about 6-inches away from the valve and, if you feel heat, you need to investigate further under the house. The fix is simple: replace the TPR valve.

    Another way that hot water can leak is from a pipe failure under the floor slab. Locating it can be difficult because the soil absorbs the moisture until the leakage becomes heavy enough to saturate the area and come up through the slab. We use an infrared camera during our home inspections to check for pipe leakage and the infrared image below shows the white-hot line of a hot water pipe at the floor slab next to a wall, and the hot water spreading outward around it.


    Finding this kind of leak without fancy technology means you need to shut off all the water fixtures in your home—including the ice maker—and see if the spinner at the center of the meter dial is still moving slowly. This would indicate a leak, but not necessarily a hot water one. After that, you can search for moist areas in the floor and walls with hot water running in the area, and a $30 infrared gun thermometer may help find a warm spot. A cool moist spot may indicate cold water pipe or drain pipe leakage. Fixing a pipe leak under the slab is messy and expensive, but it will only get messier if left unrepaired.

Pool pump running continuously - Pool pumps use a lot of electricity and are meant to run for only for part of the day. If the pump timer fails or has been reset to “ON,” you will definitely see a jump in your electric bill. 

Heat pump performing poorly - Heat pumps use a circulating refrigerant gas to collect heat from inside a home and move it outside during the summer, then they reverse the flow to move outside heat inside during the winter. One measure of the performance of a heat pump is the “temperature split,” which is the difference between the temperature of the air coming into the unit and the temperature of the air going out. 

    A healthy system has a temperature split of between 16º and 24º F warmer in the winter and colder in the summer. If the system is malfunctioning or the there is a refrigerant leak, the temperature split will shrink. Until the system stops heating or cooling altogether, you may not notice that the the temperature split is half or less of what it should be; but the system will have to work twice as hard, using twice as much electricity, to produce the same comfort level as when it was operating efficiently. This means a doubling of the heating/cooling part of your electric bill.

    What can you do? If you notice that the system is running longer than normally, or that it is having a hard time adequately maintaining a comfortable indoor temperature, get it serviced. A service contract that gets the vital stats of your HVAC system checked every six months is one way to avoid this problem.

Thermostat is set at “Emergency Heat” - It may be abbreviated on the front of your thermostat to “E HEAT” or “EMER HEAT” but, if you have a heat pump system and are heating  with emergency heat instead of “HEAT,” the winter-time heating portion of your electric bill will double. There is an electric resistance heat coil in an air handler that automatically kicks on temporarily when the outside air is too cold for the heat pump to function properly or when you set the thermostat more than a few degrees below the current indoor temperature; and it will show up as “AUXILIARY HEAT” or “AUX HEAT” on the thermostat. That’s normal and alright. But if you accidentally have the thermostat on “EMER HEAT,” set it back to “HEAT.”

Damaged or disconnected ducts - When we enter a crawl space or attic in the summer and it is as cool as the interior of the home, it means there is duct leakage somewhere that needs to be located and repaired. Poke your head up  in the attic for a minute and open the access grate to the crawl space under the floor (if your home has one) to check for an unusually comfortable temperature that indicates duct leakage.

Incorrect meter reading - Many electric meters still have analog dials that a utility company meter-reader walks around the neighborhood and checks visually each month. Each of the tiny dials alternate between clockwise and counter-clockwise rotation, and sometimes they are read incorrectly. The meter reading number will be shown on your bill. If you get an astronomical bill, check your meter to see how the current kilowatt-hours reading compares the one on the most recent bill. If the current number is lower, then you’ve found the problem.
    Reading an electric meter takes a little practice, and the one shown above is at 93084. Most meters have five dials but, if yours is a four-dial type, then it is necessary to multiply the number by ten, or just add a zero at the end, to get a correct reading.

Someone is stealing your electricity - If you live in a duplex or multi-family  building, turn off the main breaker. Make sure that won’t cause any mayhem inside your home first, of course. If the meter is still spinning, or the digital numbers continue to change, then it is likely that one of your neighbors has tapped into your electric service. Hire an electrician to figure out where and fix it.

Electricity leakage - This is the most elusive and time-consuming defect to find. When a small amount of electricity, smaller than the amperage rating of the circuit breaker in the panel that it is connected to, leaks from the circuit, the breaker will not trip to indicate a problem. We are essentially talking about a short circuit with a low current flow. To find leakage, it is necessary to turn off all the circuit breakers in the panel, unplug all appliances on one circuit, then turn that breaker back on to see if there is any current flow at the meter—which would indicate current leakage. Because many appliances use electronics that continue to operate even when the unit is switched off, it is necessary to unplug everything that can be unplugged. Illuminated light switches and GFCI-receptacles with indicator lights make this test problematic. It’s likely that a current flow will only indicate that you missed something. So we suggest that, if you think current leakage is the problem, hire an electrician to evaluate your electrical system.

    Also, see our blog posts Can a short circuit cause a high electric bill? and What causes flickering or blinking lights in a house?

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Here’s links to a collection of our other blog posts about ELECTRICAL WIRING:

• Which house appliances need a dedicated electrical circuit?

• What is the maximum spacing requirement for securing NM-cable (nonmetallic-sheathed cable)?

• Is it alright to just put wire nuts on the end of unused or abandoned NM-cable or wiring?

• What causes copper wires to turn green or black in an electric panel?  

• What are typical aluminum service entrance wire/cable sizes for the electrical service to a house?

• Why is it unsafe to bond neutral and ground wiring at subpanels?

• Should I get a lightning rod system to protect my house?

• Why is a strain relief clamp necessary for the cord connection to some electric appliances?  

• Does a wire nut connection need to be wrapped with electrical tape?

• What is the minimum clearance of overhead electric service drop wires above a house roof?

• What are the requirements for NM-cables entering an electric panel box? 

• What is the color code for NM cable (Romex®) sheathing?

• Why is undersize electric wiring in a house dangerous? 

• Why are old electrical components not always "grandfathered" as acceptable by home inspectors?

• How can I find out the size of the electric service to a house?

• Can old electrical wiring go bad inside a wall? 

• What is an open electrical splice?

• What are the most common electrical defects found in a home inspection? 

• What is the code requirement for receptacle outlets in a closet?

   Visit our ELECTRICAL page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.