Diagnostic Tools-Monitoring Electricity Usage

Randy Williams and Travis Brungardt

This post originally appeared in the November, 2022 issue of Fine HomeBuilding Magazine.   You can read the FHB print version here:  Options for Smarter Home-Energy Tracking – Fine Homebuilding

A home’s electricity use is affected by many factors.  The efficiency of the home, the type of equipment in the home and the habits of the occupants all play a role.  Up until recently, monitoring electricity use took complicated equipment.  That’s all changing.  New technology allows for monitoring whole electrical panels or individual circuits through technology included the electrical panel or the overcurrent device (breaker).  Other technologies that have been around a while are aftermarket products that can be installed inside panels.  There are also options that include point of use metering or utility usage monitoring performed directly though the utility meter.  These electrical monitoring options can be installed in both new and existing construction.

Electricity usage is billed through an electrical meter that is usually located somewhere outside the home.  These meters monitor watts consumed by the home and are billed in 1,000-watt units or 1 kilowatt.  The current average electricity rate in the United States is around $.14 per kilowatt hour (kWh).  To figure cost, multiply the kWh usage by the rate.  These meters record usage for the entire electrical load of the home.  Understanding what is using electricity in the home will require some way to monitor usage of individual electrical circuits or appliances.

Old School Methods

Checking electrical usage by an individual circuit can be done by a device called a clamp-on amp meter.  By clamping the meter around an individual wire will show the electrical draw, usually displayed in Amperage.  Because electricity isn’t billed in amperage, a quick calculation will be needed to convert amperage to wattage.  We use a formula from Ohms law in the calculation, voltage x amperage = wattage.   The drawback with this monitoring system is it only gives you consumption data for a specific point in time, no recording capabilities for the average clamp-on meter.

Another old school method for monitoring energy use is with a recording watt meter.  These plug-in devices have been around for a few decades and can be very useful in monitoring and recording electricity usage by an individual appliance.  One of the most popular models is the Kill-O-Watt meter.  To use this type of electricity monitoring device, you simply plug the meter into an outlet and then plug the device or appliance to monitor into the meter.  These meters show the use of only the electrical device plugged into the meter and are limited to 120-volt circuits.  Some units are capable of recording usage over time and can automatically calculate electricity consumption of the appliance.

New Utility Meter Technology

An electrical utility meter is used to record the energy consumption of the home for billing purposes.  The older style of these meters were simply dials that spun or rotated as electrical current passed through.  Someone had to physically read the meter every month.  The modern version of an electrical meter is much more advanced.  The new version read themselves and transmit the data to a central hub.  Transmission of the consumption data can be done by power line carrier, a signal that is placed on the existing power lines, or by radio frequency, this results in the need for towers to receive and or repeat the signal.  Cellular is another option, the meter transfers data using existing cellular communication networks.  These newer meters can recognize a power outage and relay that information to the electricity provider. 

These meters also have the capability to record electricity usage.  Usually, this information is provided daily or hourly which can show periods of time with high electricity usage, some of the more advanced meters can record usage down to the minute.  An analysis of this information can show when individual equipment inside the home turns on and off.  If you understand how much electricity an appliance uses, often you can identify which appliance is in operation.

Both the old school methods of checking and monitoring electrical usage and receiving data from an electricity provider will show electricity usage, but some newer technologies make it easier than ever to track where power is being used inside a home.

Aftermarket Electricity Monitoring

There have been several companies who have developed energy monitoring equipment that are installed inside a home’s electrical panel.  They all use some sort of clamp or doughnut that is fixed around a wire to record the energy flowing through that wire.  Two popular choices in this type of equipment today are the Emporia Vue and Sense.  Both work by installing equipment inside an existing electrical panel, the two manufacturers differ on how they work.

Emporia Vue.  This system works by installing current transformers, a clamp on sensor around a wire.  There are options to monitor only the main service conductors feeding the electrical panel (monitoring the entire service panel) or smaller clamp on sensors can be added to monitor individual electrical circuits at the breaker.  This second option will provide the user with the most detailed information on a home’s electricity usage.

The sensors are plugged into a central hub.  This hub is connected to a home’s WIFI system which communicates with the Emporia Vue app, a free service.  You can view the data on the app in real time and the information is recorded for later view.  According to the manufacturer, 1 second data is retained for 3 hours, 1 minute date for 7 days and the 1-hour data is retained indefinitely.

One of the drawbacks with this system is the electrical panel becomes very cluttered.  All those current transformers and associated cables take up a large amount of space inside the panel.  Any changes to the panel will require more time to remove or relocate the equipment.  This is where the second system, Sense, might be beneficial.

The Sense Energy Monitor uses a central hub, but only one set of current transformers installed on the main service conductors feeding the electrical panel.  The system “learns” the electrical usage of the different appliances and devices in the home by using machine learning detection.  It takes a little time, but eventually the system will be able to differentiate the different pieces of electrical equipment and track the energy use.

There may be some errors in recognizing which equipment is operating at a given time when using the Sense, but the overall electricity use of the home will be accurate, and there is a lot less equipment and wires cluttering the electrical panel.

Both these systems will provide good information as to where and when a home’s electricity is being used, which may result in a change to a homeowner’s habits or to replacing an appliance with something more energy efficient.  But what about if the home is new?  Are there options to include this technology without the need for an aftermarket solution?  Yes!

Smart Service Panels and Breakers

There have been a number of advancements in the last decade from the panel manufacturers themselves for monitoring energy use, most of which rely on Wi-Fi enabled “Smart” Breakers that transmit data through a hub to an app on the owner’s smart phone in order to share information about usage or provide remote control of that breaker. There are various different levels of control among the different manufacturers, but the basics are very similar despite the different proprietary gear in the field or the unique brand of the application on the users Smart-

Eaton offers what it refers to as the EMBC (Energy Management Circuit Breaker) which allows for real time energy use monitoring, scheduling, notifications and remote ON/OFF control through its associated Smart Energy Manager App. This functionality is similar to Square D and Leviton Smart breakers but since Eaton’s EMBC is compatible with both new and legacy BAB and BR load centers it has even greater potential for adoption. Any single and two pole BR breaker in amperages from 15-50 is currently available and could swap into any existing BR panel with full functionality. Eaton also offers the Green Motion EV smart breaker for Electric Vehicle charging, which offers all the same data and control as well as fast charging and Energy Star Certification. It also takes advantage of the scheduling portion of the app, allowing the user to plug in when they arrive home but delay the charging until later. Then they can purchase power overnight when it’s in lower demand and therefore less expensive. Eaton does not currently, but soon will have GFCI and Arc-fault protections in these smart breakers, though the EV smart breaker does include ground fault protection as required per UL requirements for EVSE.

The 42 space Leviton Smart Load Center featured in Fine HomeBuilding issue 277 (9/18 McCombe) utilizes “Smart” circuit breakers with Wi-Fi capability and a hub to transmit data to a smartphone app. This gives the user access to energy use data specific to individual circuits with the Wi-Fi connected breakers on them- potentially all of them exclusive of the main. There is also an alert feature and remote control to allow the user to trip a breaker from their phone if they so desire. This function could be useful in a number of ways if a problem were detected but also if one left the electric water heater on at the cabin after returning home from the weekend away.

The approach that Square D brought with its Energy Center is more all-in-one as detailed in Fine HomeBuilding 300 (7/21 Wotzak). This single cabinet of hardware includes the meter base, 60 space QO panel, and is both solar and generator ready. It uses Schnieders Wiser Energy kit, a monitoring hub for each circuit across the wireless interface to their app, which offers much same functionality as those listed above.

The 32 space SPAN load center is similar in that it includes the hub which transmits the usage data from each circuit to the SPAN app. SPAN also has a compatible EV charger, their Drive module, which in conjunction with the SPAN panel and app, allows the user to direct their solar generated power to the EV charger rather than back to the grid since utilities often buy back power at less than the rate they sell it for. SPAN offers both stand-alone new construction panels for indoors as well as an exterior meter base with integrated panel cabinet in one like the Square D Energy Center. Both solutions lack a proprietary breaker and instead use a “standard 1” circuit breaker” from other manufacturers.

Just as someone hoping to lose weight might start by counting calories, becoming aware of one’s unnecessary usage pretty directly leads to reduced consumption. These Smart breakers and panels, in conjunction with their Smartphone applications allow for just that.


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