Short answer
Load balancing measures how much electricity the whole house is using and throttles the EV charger back as soon as the rest needs more. That way the main fuse stays intact. With a connection of 3x25A or lighter and an 11 kW EV charger it is almost always needed in practice.
Who this article is for For anyone who has or is considering an EV charger and wonders whether the connection can cope. Setting it up and measuring is work for the electrician, but the principle is easy to follow.
The problem in one sentence
Your household connection has a limit, usually 1x35A or 3x25A. An 11 kW EV charger draws 16 amps per phase, for hours on end. Add an induction hob, an oven, a tumble dryer or a heat pump and you are over the limit. Then the main fuse blows, and that is behind a seal.
What load balancing does
A metering module goes into the meter cupboard with current clamps round the main conductors. It continuously measures what the whole house is using. If the rest of the house needs more, the EV charger gets the message to throttle back, down to 6 amps. When the oven goes off, the car charges faster again.
That happens within seconds and you notice nothing in the house.
Static or dynamic
Static means the charger gets a fixed limit, for example never more than 10 amps. Simple, but you always charge slowly, even at night when nothing else is on.
Dynamic limiting costs a metering module and gives you charging time every night.
Dynamic means measuring and adjusting. That is what you want: full power at night, gentler while cooking.
| Static | Dynamic | |
|---|---|---|
| Metering module needed | no | yes |
| Charging speed at night | limited | full |
| Chance of the main fuse blowing | small | very small |
| Extra costs | none | module plus fitting |
Several chargers
With two chargers on one connection, for example a family with two electric cars or a business, the system divides the available power over the chargers. Whoever plugs in first does not get everything: it is shared fairly or allocated in turn, depending on the brand.
For businesses and owners' associations (VvE) this quickly becomes a system in itself. More on that in EV chargers for an owners' association (VvE) or business.
Does it work with every brand
Almost every serious wallbox can do it, but not every module suits every brand. Zaptec, Alfen, Wallbox and Easee all have their own metering module or support a standard meter via Modbus. So buy the module with the charger, not separately.
I can tell what fits in your meter cupboard from the consumer unit and the connection. Often there is already a smart meter that does part of the work.
From my own work
A customer in Geleen called because the main fuse blew twice a week, always around dinner time. The supplier had set the EV charger to full power, the induction hob was on and the heat pump was running too. A metering module in the consumer unit and the charger set to dynamic balancing, and it has never happened again. The car sometimes charges a bit more slowly now, but nobody notices.
When to call an electrician
- The main fuse blows while charging
- You have a heat pump, induction and an EV charger on the same connection
- The EV charger was fitted by someone else and there is no metering module in the consumer unit
Adding a metering module is usually an hour's job. Feel free to call +31 43 204 18 26 or request a quote.
Frequently asked questions
Do I always need load balancing?
Not always. With a 3x25A connection, an 11 kW EV charger and an ordinary household you usually do, certainly with induction or a heat pump as well. With a light charger or a heavy connection you can do without.
Will my car charge more slowly then?
Only at the moments when the rest of the house needs electricity. As soon as the oven goes off, the car goes back to full power. If you charge at night you will hardly notice anything in practice.
Does load balancing work with every EV charger?
Almost every serious wallbox can do it, but the metering module has to suit the brand. So buy the module with the charger and not separately.
Further reading
EV charger at home: single-phase or three-phase, and which protection
The choice depends as much on your car as on your connection. With the costs, the RCD debate and why load balancing is not an optional extra.
Which cable to the EV charger, and what the distance does
The further the charger is from the meter cupboard, the thicker the cable has to be. That is usually the item that decides the price.
Which RCD protection belongs with an EV charger
An EV charger can produce a DC fault that an ordinary RCD is blind to. It needs protection that can see it.
Questions and comments
Ask your question below. Ask before 17:00 on a working day and you get an answer from Kevin himself the same day. No account needed, and your email address does not appear on the site.