EV Charger Load Management: Why Your Building May Not Need a Supply Upgrade
The most common objection to installing multiple EV chargers is supply capacity. The building already uses most of its available electrical supply for lighting, heating, equipment and other loads. Adding four, six or ten EV chargers would push the demand over the supply limit. The traditional solution is a supply upgrade from Electricity North West — a process that costs £3,000 to £15,000 or more and takes 6 to 16 weeks.
But there is a better option for most buildings. Dynamic load management allows multiple EV chargers to share the available supply capacity by reducing charger output when the building's other loads are high and increasing it when demand drops. In many cases, load management lets you install three to five times more chargers than you could without it — and it costs a fraction of a supply upgrade.
How Dynamic Load Management Works
The Problem It Solves
A typical small commercial building in Manchester has a 100 A single-phase supply. The existing loads (lighting, heating, computers, kitchen equipment, security systems) draw an average of 40 to 60 A during business hours, with peaks of 70 to 80 A when multiple systems run simultaneously.
A single 7 kW EV charger draws 32 A. Two chargers draw 64 A. Without load management, adding two chargers to a building already drawing 60 A would require 124 A — exceeding the 100 A supply.
The Solution
A dynamic load management system (also called a Current Transformer or CT clamp system) monitors the building's total electrical demand in real time. It measures the current flowing through the main supply cable using a CT clamp fitted inside the distribution board.
The system knows the building's total supply capacity (100 A in this example). It continuously calculates how much spare capacity is available by subtracting the building's current demand from the total supply limit. That spare capacity is shared across the EV chargers.
Example throughout a typical business day:
| Time | Building Load | Available for EV Charging | Charger Output (2 chargers) | |------|--------------|--------------------------|---------------------------| | 06:00 | 20 A | 80 A | 32 A each (full power) | | 09:00 | 65 A | 35 A | 17.5 A each (reduced) | | 12:00 | 75 A | 25 A | 12.5 A each (reduced) | | 14:00 | 55 A | 45 A | 22.5 A each (increased) | | 18:00 | 25 A | 75 A | 32 A each (full power) | | 22:00 | 15 A | 85 A | 32 A each (full power) |
The chargers never draw more than the available capacity. The building never exceeds its supply limit. No supply upgrade required.
What the Driver Experiences
In most cases, the driver notices nothing. The charger adjusts its output automatically and silently. The vehicle's battery management system adapts to the available power. The only practical effect is that charging takes slightly longer during peak building demand periods.
For a vehicle parked for an eight-hour shift, the difference is negligible. Even at reduced output during peak hours, the charger delivers enough energy over the full day to cover a typical commute. A car that would be fully charged in six hours at full power might take seven or eight hours with load management — but since the car is parked for eight hours anyway, this makes no difference to the driver.
Types of Load Management
Static Load Management
The simplest form. The installer calculates the maximum available capacity for EV charging (total supply minus maximum expected building load) and permanently limits each charger to a fixed output. If 40 A is available for charging and there are four chargers, each charger is limited to 10 A (2.3 kW) permanently.
- Cost: £0 (just a charger configuration setting)
- Limitation: Conservative — the charger output is always limited, even when the building is nearly empty and full power is available
- Best for: Simple installations where the available capacity comfortably supports the chargers at reduced power
Dynamic Load Management (CT Clamp)
The system described above. A CT clamp on the main supply cable feeds real-time demand data to the chargers (or to a load management controller). Charger output adjusts continuously based on available capacity.
- Cost: £500 to £1,500 for the system (CT clamp, controller, cabling and configuration)
- Limitation: Requires compatible chargers — most modern smart chargers (Easee, Ohme, Wallbox, Alfen, ABB and others) support dynamic load management
- Best for: Most commercial, workplace and multi-charger installations
Network-Level Load Management
For larger installations (10+ chargers), a central controller manages the total charging load across all chargers. It can prioritise chargers (fleet vehicles might get priority over staff vehicles), schedule charging to off-peak tariff periods, and integrate with solar PV generation.
- Cost: £1,500 to £5,000 depending on complexity
- Limitation: Requires a compatible back-end management system and network connectivity for all chargers
- Best for: Large car parks, fleet depots, multi-site operators and installations with solar PV
Cost Comparison: Load Management vs Supply Upgrade
Supply Upgrade from Electricity North West
| Item | Cost | Timeline | |------|------|----------| | Application and design | £500 to £1,500 | 2-4 weeks | | Upgrade work (single-phase to three-phase or capacity increase) | £3,000 to £15,000+ | 6-16 weeks | | New distribution board or sub-main | £1,000 to £3,000 | Included in installation | | Total | £4,500 to £19,500+ | 8-20 weeks |
Dynamic Load Management
| Item | Cost | Timeline | |------|------|----------| | CT clamp and controller | £300 to £800 | Available immediately | | Installation and configuration | £200 to £700 | 1-2 hours during charger install | | Total | £500 to £1,500 | Same day as charger installation |
The saving is typically £4,000 to £18,000 and 8 to 20 weeks of project time.
When You Genuinely Need a Supply Upgrade
Load management is not a universal solution. Some situations genuinely require more supply capacity:
High Charger Count with High Utilisation
If you need 20 chargers and all of them will be in use simultaneously (a fleet depot, for example), load management alone may reduce the charging rate to impractical levels. The maths matters: if you have 30 A of spare capacity shared across 20 chargers, each charger gets 1.5 A — not enough to charge a vehicle.
Rule of thumb: Dynamic load management works well when the available spare capacity (in amps) is at least 6 A per charger during peak building demand. Below that, charging times become impractical.
DC Rapid Chargers
DC rapid chargers (50 kW+) draw fixed, high power levels and do not support the same dynamic load management as AC chargers. A single 50 kW charger requires approximately 72 A on a three-phase supply. You cannot share that load with other chargers in the same way. If you are installing rapid chargers, you will almost certainly need dedicated supply capacity.
Building Already at Maximum Demand
If your building regularly draws 95 to 100 per cent of its supply capacity during normal operations, there is no spare capacity for load management to work with. In this case, you need either a supply upgrade or energy efficiency improvements to reduce the base load before adding chargers.
Planned Building Expansion
If you are planning to add significant new electrical loads (a commercial kitchen, air conditioning, additional office space, production equipment), factor those future loads into your EV charging plan. A supply upgrade that covers both the new building loads and the EV chargers may be more cost-effective than upgrading twice.
How Your Installer Should Assess This
A competent EV charger installer should follow this process:
1. Measure existing maximum demand: Using meter data, demand monitoring or a supply capacity assessment 2. Calculate the proposed EV charging load: Based on the number and power rating of chargers 3. Model the load management scenario: Calculating minimum charger output during peak building demand 4. Present both options: Load management with projected charging performance, and supply upgrade with costs and timeline 5. Recommend the right approach: Based on your usage pattern, number of chargers, and budget
If your installer jumps straight to recommending a supply upgrade without assessing load management, get a second opinion. Some installers default to supply upgrades because they are simpler to specify, even when load management would work perfectly and save you thousands.
Solar PV Integration
If your building has solar panels, load management becomes even more powerful. The system can use the CT clamp to detect solar generation and direct surplus energy to the EV chargers. During sunny periods, the chargers run at higher output — effectively charging vehicles from free solar electricity.
This integration is straightforward with most smart charger systems and adds minimal cost to the load management setup. Manchester receives enough solar irradiation to make this worthwhile, particularly during the longer daylight hours from April to September.
Get an Honest Assessment
Manchester Compliance assesses every EV charging installation for load management suitability before recommending a supply upgrade. We install dynamic load management systems with all major charger brands and provide transparent cost comparisons between load management and supply upgrade options.
If load management will work for your building, we will tell you. If you genuinely need a supply upgrade, we will tell you that too — and handle the Electricity North West application on your behalf.
Call 0161 706 0946 for a free site survey and load assessment, or email hello@manchestercompliance.co.uk.
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