As home technology has evolved, so has the load demand placed on the electrical panel of the average home.
One area in which that demand increase is most obvious is electric vehicle charging. There were 14 million new EVs registered in the US in 2023 alone, increasing by 35% from 2022 to 2023. As the need for home charging continues to grow, codes and standards are evolving to address this load demand.
Electric vehicle chargers are among the largest electrical loads on a residential panel. Unlike most other larger electrical loads, EV charging draws electrical power continuously for hours at a time to charge a vehicle’s battery.
For homes with 100A service or those that already have a very heavy electrical load, charging an EV can push their panel past its capacity. A common example is charging the car while also cooking dinner on an electric induction stove and using the air conditioner. This could easily exceed the current limit of the main circuit breaker, causing it to trip. Tripping the main circuit breaker disrupts the power supply to every load in the panel, which is something that you would not want to do repeatedly.
Load splitters – a viable solution?
So how are homeowners working around this problem?
An increasing number of property owners are purchasing load splitter devices from online retailers and self-installing them to help manage domestic loads.
Load splitters plug into existing 240V outlets for circuit sharing between a home’s appliance and an EV charger, or two EV chargers. These devices have grown in popularity, not just because of the perception that they can help reduce strain on overloaded circuits, but also because they are thought to minimize the need for costly panel upgrades. This is particularly the case in homes with older, 100A systems that were not built or designed to meet the load demands of today.
However, there are real limitations associated with load splitters. Many homeowners who install a load splitter do not have the necessary electrical expertise. For instance, it is critical to perform load calculations before installing a splitter. Most homeowners don’t know this, so they are essentially treating load splitters as a ‘plug-and-play’ solution.
The dangers of not doing a load calculation include an increased risk of system overload, which trips the main breaker. Persistent tripping can cause the breaker to wear and generate excess heat, which becomes a major fire hazard.
What’s more, many people purchase load splitters from online retailers. Some online marketplaces may sell products from overseas that may not have been certified with US safety and quality standards.
This is particularly concerning given that NEC 220.60, which governs non-coincident load calculations, was not originally designed to account for the growing use of high-demand, continuous loads like EV chargers.
Section 220.60 – load splitters and the existing code
Section 220.60 relates to non-coincident loads, in other words, loads that are unlikely to be in use simultaneously. While this worked for many years in applications such as HVAC and alternating pump systems, the addition of high-demand devices, particularly those with continuous loads like EV charging, revealed gaps within the NEC requirements. The correct calculation of EV charging loads, branch circuit sizing, and listing of equipment that performs energy management functions were recently added to the Code to address these gaps.
A better path with NEC 220.70, Article 750 and energy management systems
Another potential option for homeowners is home energy management systems (HEMS), which are covered by NEC 220.70 and Article 750. The code’s remit includes managing the entirety of a home’s utility service load. Crucially, this can help avoid costly and time-consuming upgrades by allowing for a more precise calculation based on the managed electrical demand in their property.
Rather than sizing systems based solely on traditional calculation methods or attempting to apply non-coincident load considerations (as outlined in NEC 220.60), NEC 220.70 and Article 750 introduce the concept of an Energy Management System (EMS). An Energy Management System is used to limit the current by shedding the load if the home’s total load exceeds the maximum ampere setpoint. By using active load control based on the maximum setpoint, NEC 220.70 and Article 750 ensure that electrical systems can supply additional loads such as EV charging, which is often the reason behind service upgrades. For example, a household might have several high-power appliances, but it is rare for all of them to be running at the same time. Through the ability to impact the load calculation, the use of energy management systems, NEC 220.70 and Article 750 can reduce the need for increasing service capacity and avoid the risks of improper use of load-splitting devices in the home.
Over the next few years, we expect more homeowners to look for ways of managing electrical demand without having to carry out expensive upgrades.
Familiarity with NEC 220.70 and Article 750 allows electricians to better advise customers on how to avoid these service upgrades and ensure more accurate load calculations.
To learn more about Schneider Electric’s solutions to simplifying home electrification, visit our Connected Home page.
The information in this blog is for educational purposes only and does not replace professional advice. Proper training and relevant certification are essential before undertaking any electrical work.
Working with electricity can be hazardous without a thorough understanding of the National Electrical Code (NEC). Always follow the latest NEC regulations applicable in your state, when working with electricity.
For more information on the NEC, please visit the National Fire Protection Association (NFPA) website.
Add a comment