The problem load management solves
Many Edmonton homes have a 100 A service that was perfectly adequate until someone brought home an electric vehicle. A load calculation says the house plus a full-rate charger is more than the service can carry, at least on paper, and on the coldest evenings in practice.
But most of the time the house uses far less than its peak. Your oven, dryer and furnace fan are rarely all running at 2 a.m., which is exactly when the car is charging. A load management device takes advantage of that. It watches the total load on your service and turns the charger down, or pauses it, whenever the rest of the house needs the capacity.
The Canadian Electrical Code recognizes these systems under the name electric vehicle energy management system, or EVEMS. When one is installed and set up properly, the charger does not have to be added to your load calculation in the usual way, because it can never push the service over its limit.
How it works
Every EVEMS does the same three things: it measures, it decides and it controls.
- Measure. Current sensors are installed on the service conductors, or on the circuits being shared, so the system knows how much the house is drawing at every moment.
- Decide. The controller compares that number with the limit your electrician programs in, based on the load calculation.
- Control. If the house load climbs, the controller tells the charger to reduce its current or switches it off. When the load drops, charging resumes automatically.
Current sensors are installed inside the panel or meter area on live service conductors. This is work for a licensed electrician under a permit, never a do-it-yourself job.
What it looks like on a real day
Here is how a managed charger typically behaves through a January weekday. Overnight the house is quiet and the car charges at full rate. In the morning the car is unplugged. At supper the oven, dryer and furnace all run, and the charger is held back until things settle down.
The controller reacts within seconds, much faster than a breaker would trip from an overload. That is what makes it safe to rely on: the limit is enforced continuously, not just on average.
For most commuters this makes very little difference to how full the battery is by morning. You lose some charging during a few busy hours, then make it up overnight.
The main types
There are three common approaches. Which one suits you depends on your panel, your charger and whether you already own one.
| Approach | Good fit when | Things to know |
|---|---|---|
| Built into the charger | You are buying a new charger anyway | Not every charger has this feature, and it has to be set up during installation. |
| Standalone EVEMS | You already own a charger, or want flexibility to change it later | A separate box is mounted near the panel. Works with a wide range of chargers. |
| Circuit sharing | An existing large circuit, such as a dryer, is near the parking spot | Only one load can run at a time, so laundry and charging take turns. |
With two EVs, many chargers can also share one circuit between them, splitting the available current so both cars are full by morning.
Load management or service upgrade?
Load management is usually the faster and less disruptive path. There is no utility disconnect, no new meter base and often a much smaller scope of work. It is a good choice when your service is in decent condition and you simply need to fit one more large load.
A service upgrade is the better call when:
- Your existing service or panel is old, damaged or at the end of its life.
- You are also planning a heat pump, air conditioning, a hot tub or electric heat.
- You plan to install rooftop solar and want room for the solar connection. See solar basics for Alberta homes.
- The household needs fast charging for two vehicles at busy times of day.
What drives the cost of either option is mostly the distance from the panel to the parking spot, the panel's condition and how much finishing work is in the way. We can price both side by side so you can compare. Start with can my panel handle an EV charger if you are not sure where your home stands.
What to expect from the installation
Our EV load management service includes the load calculation, the permit, installing and programming the device, and showing you how it behaves. The setting chosen during installation is part of what the inspector reviews, so it should never be changed by anyone but an electrician.
It is also a good idea to label the device and keep the installation paperwork with your house records. If you sell the home, the next owner and their inspector will want to know the charger is managed and why.
If you notice the car charging much slower than expected, check the charger's app first. It usually shows when charging was reduced and why. If something still seems wrong, give us a call and we will look at the data with you.
Common questions
Will a load management device make my car charge too slowly?
For most households, no. The charger is only reduced during short periods of high house load. Overnight, when most charging happens, it usually runs at full rate.
Can I add load management to the charger I already own?
Usually, yes. A standalone EVEMS works with many chargers. We will confirm compatibility before recommending one.
Is load management allowed by code in Alberta?
Yes. The Canadian Electrical Code, as adopted in Alberta, recognizes electric vehicle energy management systems. The equipment must be certified for use in Canada and installed under a permit.
Does it help with solar or a heat pump too?
Some systems can manage more than one load, but the details vary by product. If you are planning other big additions, tell us early so we can choose equipment that fits the whole plan.
Codes and permit rules change and every building is different. For work on your system, talk to a licensed electrician and your local permit authority.