EV Charger Load Balancing & Energy Management
If charging your EV causes your consumer unit to trip, or you're worried about overloading your supply, load management is the answer. Here's how it works.
Why Overloading Happens
A typical UK home has a 100A single-phase supply (sometimes 60A in older properties). A 7.4kW EV charger draws ~32A. Add in an electric cooker (~30A), electric shower (~40A), and other loads, and it's easy to see how the mains fuse can be stressed during peak evening hours.
Without any management, the EV charger draws its full rated current regardless of what else is on in the house. Load management solves this by monitoring the total household draw and reducing the charger's output when other loads are high.
Static vs Dynamic Load Management
| Static Load Management | Dynamic Load Management (DLM) | |
|---|---|---|
| How it works | Charger limited to a fixed maximum current at all times | Charger current adjusted in real time based on total household demand |
| CT clamp required? | No | Yes |
| Maximum efficiency | Moderate — always restricted | High — uses available headroom |
| Best for | Tight supplies with consistent loads | Most homes — maximises charge speed while protecting supply |
A Current Transformer (CT) clamp fits around the incoming mains cable and measures total household current draw in real time. The charger reads this value and adjusts its output to keep total demand within the supply limit.
Multi-Charger Power Sharing
For properties with multiple EV chargers — such as households with two EVs, or small commercial premises — power sharing divides available capacity between units. When both cars charge simultaneously, each gets a proportional share. When only one is charging, it can use the full available headroom.
EcoHarmony's three-phase distribution boards are suitable for multi-charger commercial and residential installations. View three-phase distribution boards →
Frequently Asked Questions
My consumer unit trips when I charge the car. What do I do?
This typically means the total demand is exceeding your supply capacity. Options include: installing a charger with dynamic load management (DLM), limiting the charger to a lower current via its settings, upgrading your supply with your DNO, or scheduling charging to off-peak times when other loads are lower.
Does dynamic load management slow my charging?
It can — but only when other high loads are present simultaneously. When the house is quiet (overnight, for example), DLM allows the charger to run at full speed. The result is faster average charging compared to static limitation.
Do I need a DNO upgrade for an EV charger?
Most properties don't need one. A standard 7.4kW charger on a 100A supply is fine, especially with DLM. If your supply is 60A or you regularly use very high loads simultaneously, consult your DNO. Upgrades are free in most cases.