Key points
- A dual 22kW pedestal at full power needs 64A per phase, which many supplies can't spare all day.
- Dynamic load balancing measures what the building is using and gives the chargers whatever is left.
- Hotels and venues do most of their charging in the evening and overnight, when spare capacity is highest.
- Limiting the chargers' load can change how the DNO treats your connection.
- It can't create power. At busy times, cars charge more slowly.
The problem it solves
Every building has a limit on how much power it can draw at once. That limit is set by the DNO's main fuse, called the cut-out, and by any capacity agreed with the network.
EV chargers are a big new load. 22kW AC charging uses 32A per phase on a three-phase supply (bestchargers.co.uk). Our dual 22kW charger has two sockets, so at full output it needs 64A per phase.
Add that to a hotel kitchen at dinner service, a laundry and a spa, and many supplies would run out of room. Load management is how you fit chargers in without paying for a bigger supply. It's also one of the main tools we use when a site runs into grid capacity limits.
Static and dynamic load management
There are two broad approaches.
Static
The chargers get a fixed maximum, set low enough that the building can never go over its limit, even at its busiest. It's simple and cheap. The downside is that the chargers are held back all the time, including at 3am when the building is barely using anything.
Dynamic
A meter on the incoming supply measures what the whole building is using, moment to moment. The charger reads that figure and takes whatever is left, up to a safe limit.
When the kitchen fires up, the chargers turn down. When it goes quiet, they turn back up. Dynamic load balancing is an option on our most popular charger, the dual 22kW pedestal.
A worked example on a 100A supply
The figures below are illustrative. Every building is different, and the real numbers come from a load survey.
Say a hotel has a 100A three-phase supply. We set the chargers so the total never goes above 90A per phase, leaving some headroom. Each amp per phase is worth roughly 0.7kW across the three phases.
| Time | Building load (per phase) | Left for the chargers | Roughly what that gives |
|---|---|---|---|
| 7pm, dinner service | 70A | 20A | about 14kW shared between both sockets |
| 10pm, bar winding down | 45A | 45A | about 31kW shared between both sockets |
| 2am, building quiet | 25A | 65A | enough for both sockets at full 22kW |
Static management on the same supply would have to plan for the worst moment. That means capping the chargers at 20A all night, about 14kW between two cars.
Dynamic management gives the cars about 14kW during dinner, then full power once the building quietens down. Over a night, that adds up to far more charging from the same supply.
What the cars actually take
Most cars accept 7.4kW or 11kW on AC, and only a few take 22kW. An 11kW car draws about 16A per phase. In the example above, two 11kW cars would charge at their full speed from about 10pm onwards.
That's why the 22kW figure matters less overnight than people think. Our 7kW vs 22kW guide explains what different cars really get.
How the dual pedestal shares power
Each socket on the pedestal can deliver up to 22kW. With load management, the limit applies to the pedestal as a whole.
When one car is plugged in, it can have everything available, up to what the car accepts. When a second car arrives, the available power is shared between the two sockets. When the first car is full, the other can take more again. We set the exact behaviour when we commission the charger, based on your survey.
On sites with more than one pedestal, the same idea applies across the group. Several chargers share one allowance instead of each needing its own.
Overnight scheduling
Hotels, wedding venues and holiday parks have an advantage here. Most cars arrive in the evening and leave in the morning, so they're plugged in for many hours.
At 7kW, a car gains roughly 24 miles of range an hour (derived from LGA and Zapmap figures). Over a night, almost any car can be fully charged, even if it charges slowly during your busy evening hours.
Scheduling can go further. The chargers can be set to hold back during your known peak, then pick up once it's past. If your business tariff has cheaper night rates, charging can lean into those hours too. Business tariffs differ, so check yours.
How it affects the DNO
The national form that installers use to tell the DNO about new chargers treats a limited load differently from an unlimited one (ENA EVCP and HP form).
If the chargers are limited so total demand stays below the cut-out rating, that can change which route applies. Sometimes it's the difference between connecting and notifying, and applying first and waiting. Northern Powergrid still has the final say, so we check this at survey.
Signs your site needs it
Load management is worth considering if any of these apply:
- The chargers will share a supply with a commercial kitchen, laundry, spa, pool or heat pumps.
- Your supply is already busy at its peak, often on a winter evening.
- You expect both sockets to be in use at the same time on a regular basis.
- You'd like to add more chargers later without another supply upgrade.
- You're on a rural site where a network upgrade could be slow or costly.
If none of these fit, a simple fixed limit may be enough. The survey will tell you which way to go.
Holiday parks and caravan sites
Parks have an extra wrinkle. Pitches and lodges often have their own hook-up circuits, and those loads rise and fall with occupancy and the weather.
It's best to feed chargers from their own circuit, kept separate from the hook-ups, and to let load management watch the park's total supply. That way, a busy bank holiday weekend slows the chargers down instead of tripping a pitch. Our holiday park page covers layout and access.
What it can't do
Load management shares power. It doesn't create any.
- At your busiest times, cars charge more slowly.
- If you want lots of chargers and your peaks clash with peak charging, a bigger supply may be the better answer.
- The system relies on an accurate meter reading and a working connection between the meter and the charger, so it has to be installed and set up properly.
For most single-pedestal sites, none of this is a problem. For bigger plans, it's worth weighing a supply upgrade against a phased approach that grows with demand.
Next step
A free site survey includes a look at your supply and whether load management would avoid an upgrade. To see how supply costs fit with each way of paying, compare our packages.