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Controlling EV charging at home: Two major ways, two different experiences

In our EVEMS series article “What is an Electric Vehicle Energy Management System (EVEMS) and why do I need one?”, we explained how load balancing or load management will control and monitor an electrical load (ex. charging station) so that power can be used efficiently, safely and cost-effectively, and to avoid significant upgrades to infrastructure. You can also read how an EVEMS can positively impact the grid here.

In this article we will look at two major ways to manage the load of an electric vehicle charging station at home: branch circuit switching and feeder monitoring. We also review the safety and benefits of using a charge controller for management, and highlight differences in EV energy management system products for single-family (and townhome) households.

Why do I need to know about load management?

Most people turn to load management for any of these reasons:

Adaptability: You want to manage several high-powered devices (EV charging stations, a hot tub, HVAC, or power tools) on a panel already at or near capacity
Cost Savings: You want to save money by avoiding major infrastructure or panel upgrades
Environmental Benefits: You want to save energy by optimizing the management potential of your existing infrastructure
Security: You want a safeguard and peace-of-mind when operating charging equipment
Efficiency: You would like to be energy efficient using what you already have

Realizing the importance of these benefits to the home charging experience almost always takes place after an electrician or contractor inspects an electrical panel that is at or near capacity (read here for a story from one of our client’s who experienced just that).

A panel upgrade is one solution but comes at a great cost, can involve long wait times, and can be a major renovation when all you’re trying to do is add an EVSE or charging equipment to your home panel.

The two alternatives you may not have heard of are: branch circuit switching and feeder monitoring. Both are both ways to manage or power an electric load using a charge controller, but are accomplished differently.

Branch Circuit Switching

Branch circuit switching takes an existing circuit, such as a 220-240 volt branch that would be used for high-power consuming appliances (ex. ovens or dryers), and splits the wire for use with another appliance. A device, like a load miser, is placed between the panel and appliances and a magnetic switch directs current to whichever device is turned on. This means that if the device powers an oven and an EV charger, an oven will turn off when an EV charger turns on, or an EV charger will turn off when an oven is on. 

The limit to branch circuit switching is that the appliances being powered need to have the same amperage (and so EVSE above 40A are not recommended). Using the example of a load miser above, an oven and an EVSE need to be close in distance, making this a solution only suited for single-family homes (and almost exclusively homeowners with a garage).

Also, a branch circuit switching device will not manage a panel, only the power between two preset appliances. While this can be a short-term solution to a panel upgrade, it is not a true alternative because you’re still adding resources to your panel without freeing up energy.

Feeder Monitoring

A charge controller that manages power with feeder monitoring uses current transformers (CTs), which are plastic clips that can “read” an electric current and are attached to the feeder (between the electrical panel and the metering system). While branch circuit switching manages the power of a single circuit, feeder monitoring is all-inclusive in the sense that a feeder monitoring device responds to what’s going on at the level of the whole panel and will be triggered according to the limits set by panel capacity, eliminating the possibility for overloading.

Current transformers (CTs)

Current transformer installation

For example : you might hold an event at home that requires powering several appliances at once. A product like the DCC by RVE (a feeder monitoring device) temporarily powers down the 60 amp EVSE that’s charging your Ford F-150 Lightning when the oven, washer, dryer, tv and sound system, hot tub, and more are simultaneously using 80% or more of your panel’s capacity. This is one significant difference from branch circuit switching, which would not be able to indicate that your panel is at capacity and would not be able to automatically shut down (or manage) the energy of an appliance.

Comparison of products on the market

Feeder Monitoring with The DCC by RVEFeeder Monitoring using other devicesBranch Circuit Switching
DCC-9
DCC-10
DCC-11
DCC-12
Blackbox
Simpleswitch 240M
Smart Current Sensor (EV Duty)
Power Meter (Wallbox)
Load miser (Dandy)
Simpleswitch
Divvee (LoadshareTechnologies)
Smart Splitter (Neocharge)
Electric Range Buddy (BSA Electronics)
Splitter Switch (Splitvolt)
For single family and multi family homes

X

X

Certified by the highest North American Standards

X

X

An original patent

X

X

No additional, hidden, recurring, or subscription costs

X

X

Guarantees infrastructure for future installations

X

X

Can be installed prior to purchase of an EV or charging station

X

X

Compatible with all charging brands (EVSE agnostic)

X

X

Can be used in other applications (not limited to EVSE)

X

X

Has models that protect an electrical load up to 60A

Sometimes

Rarely

Models available for indoor and outdoor use

Rarely

Rarely

Models available with and without an integrated breaker

X

X

Decision making is done locally (no need for wifi)

Sometimes

X

Uses certified industrial components

Sometimes

Sometimes

Available through authorized distribution channels

Sometimes

Sometimes

A known brand with a record of successful installations

Sometimes

Sometimes

Controls the operation of an electrical load and monitors the main panel

X

Sheds rather than shares an electric load

X

Keeps existing infrastructure

Reads energy in real time

Quick installation time compared to panel upgrades

Need some advice on how to choose the best product?

Look out for the following to get a product that is quality-made and guaranteed secure:

Devices that are CSA or UL-Listed
Devices that use safe and standardized, and ideally industrial-grade, components
Devices that are patented to be used for their described and intended purposes
Devices that are secure, tamper proof and cannot be easily unplugged
Devices that use the appropriate amperage for the circuit
Devices that will be compatible with the appliance you are connecting to
Devices that are rated to be used outside (if that’s what you need)
Devices that have a good history of being reliable and functional
Devices that are trusted by electricians

Using this guidance will ensure that you choose a device that is code-compliant and one that doesn’t pose an electric or fire risk. If you need additional help, an electrical professional will know which products are of a certifiable standard and grade.

Consulting with an electrician will always be your best choice when comparing the benefits and risks to electric vehicle energy management systems (EVEMS) and other electric vehicle supply equipment (EVSE) on the market. 

And remember that there is a big difference between electrical equipment (like an electric panel) and electrical appliances (like a computer). Electrical equipment should be installed by an electrician and sold by electrical distributors.

How do I choose the EVEMS strategy that is right for me?

We believe in our products and always seek the right certifications, to deliver quality, without a client having to compromise or need additional upgrades in the future. Your DCC is guaranteed to be the perfect companion to your electrical panel; the DCC safely sheds any significant connected electric loads that would otherwise cause damaging wear to your home’s infrastructure. 

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