Case Study: Servicing 15 EV Chargers at Princess House, Manchester
Manchester Compliance recently completed a full service of 15 EV chargers at Princess House in Manchester city centre — an installation our engineers originally designed and delivered three years ago. This case study explains the scope of the service, what our engineers found after three years of continuous commercial use, and why scheduled EV charger servicing matters for any business running multiple chargepoints.
The Installation: What We Built Three Years Ago
Princess House is a multi-storey commercial building in Manchester city centre with basement and ground-level car parking serving office tenants and visitors. In 2023, we installed 15 commercial EV chargers across the car park as part of the building management's commitment to providing charging infrastructure for tenants and their employees.
The original installation included:
- 15 x 7kW Type 2 socketed chargepoints — wall-mounted units across basement and ground-level parking bays
- Dedicated electrical infrastructure — a new sub-distribution board fed from the building's main supply, with individual MCBs and Type A RCDs for each charger
- Dynamic load management — a smart charging system to balance demand across all 15 units without exceeding the building's available electrical capacity
- OCPP back-end connectivity — each charger connected to a cloud management platform for usage monitoring, billing and remote diagnostics
- Associated civil works — cable containment, bollard protection for wall-mounted units, bay markings and signage
Why the Service Was Needed
Three years of continuous commercial use is a significant operating period for EV charging equipment. The chargers at Princess House were in daily use by office workers, with average utilisation of 6 to 8 charging sessions per unit per day during weekdays. That equates to roughly 5,000 to 6,000 individual charging sessions per charger over the three-year period.
At that level of use, several components are subject to wear and degradation:
- Charging cables and connectors experience repeated plugging and unplugging, bending and occasional dropping. Connector pins wear, locking mechanisms loosen and cable outer sheaths develop micro-cracks.
- Contactors and relays inside the charger switch high currents thousands of times. Contact surfaces erode, increasing resistance and generating heat.
- RCD protection devices can degrade over time, particularly Type A RCDs which are sensitive to DC fault currents. A degraded RCD may not trip at the correct threshold.
- Electrical connections — terminal screws, bus bars and cable terminations — can loosen through thermal cycling as the charger heats and cools with each session.
- Software and firmware may have accumulated updates from the manufacturer addressing security patches, communication protocol changes or performance improvements.
- Enclosures and seals on outdoor or semi-exposed units degrade from UV exposure, temperature cycling and moisture ingress.
What Our Engineers Did
We allocated a two-engineer team to carry out the full service over two days. The work was scheduled across a Tuesday and Wednesday to minimise disruption to tenants who rely on the chargers during the working week. We coordinated with the building's facilities team to notify tenants in advance and to reserve adjacent parking bays as temporary alternatives.
Day 1: Inspection and Diagnostics (8 Units)
Each charger received the following inspection and test sequence:
Visual inspection. Our engineers checked each unit for physical damage, loose fixings, water ingress, cable sheath condition, connector pin wear, locking mechanism operation, signage condition and enclosure integrity. Three chargers had visible cable sheath wear at the point where the cable exits the holster — consistent with repeated coiling and uncoiling over three years.
Electrical testing. We isolated each charger in turn and carried out insulation resistance testing on the supply cable and internal wiring, earth continuity verification, RCD trip testing (both at rated and 5x rated current), loop impedance measurement at the charger terminals, and thermal imaging of internal connections under load. Thermal imaging identified two units with elevated temperatures at terminal connections — 47°C and 52°C respectively against an ambient of 22°C. Both were traced to terminal screws that had loosened through thermal cycling.
Functional testing. Each charger was tested through a complete charge cycle using a test vehicle. We verified correct EVSE pilot signal behaviour, contactor engagement and disengagement, energy metering accuracy against a calibrated reference meter, load management response (confirming dynamic load balancing still functioned correctly across all units), and OCPP communication with the back-end platform.
Fault diagnosis. The intermittent mid-session dropout on charger 7 was traced to a degraded contactor with eroded contact surfaces. Under high current draw, the increased contact resistance caused the charger's internal protection to trip. The persistent error code on charger 12 was a communication module fault — the unit had lost its OCPP connection and was stuck in an error state that required a firmware-level reset.
Day 2: Remedial Work and Remaining Units (7 Units + Repairs)
Terminal re-torque. All terminal connections across all 15 chargers were re-torqued to manufacturer specifications. The two units with elevated thermal readings were given particular attention — the loose terminals were cleaned, re-made and re-torqued. Post-repair thermal imaging confirmed temperatures within normal range.
Contactor replacement. The degraded contactor in charger 7 was replaced with a manufacturer-approved spare. Post-replacement functional testing confirmed normal operation with no mid-session dropout.
Communication module reset and firmware update. Charger 12's communication module was factory-reset and the latest firmware version was applied. OCPP connectivity was re-established and verified. We also applied the latest firmware to all remaining chargers as a preventative measure — the update included improved thermal management algorithms and an updated OCPP 1.6J compliance patch.
Cable and connector remediation. The three cables with sheath wear were assessed. Two were within acceptable limits and were dressed with UV-resistant cable wrap as a protective measure. One cable had wear that exposed the inner sheath and was replaced with a new manufacturer-supplied cable assembly.
RCD testing results. All 15 RCDs tripped within specification. One unit's RCD trip time was at the upper end of the acceptable range (285ms against a 300ms maximum for a 30mA Type A device). We logged this for monitoring at the next service but it did not require immediate replacement.
Seal and gasket check. Two chargers in the most exposed basement position had degraded door seals. Both were replaced with manufacturer gasket kits to maintain the IP rating of the enclosure.
Summary of Findings
| Finding | Units Affected | Action Taken | |---------|---------------|-------------| | Loose terminal connections | 2 of 15 | Re-torqued, thermal verified | | Degraded contactor | 1 of 15 | Replaced | | Communication module fault | 1 of 15 | Factory reset, firmware updated | | Cable sheath wear | 3 of 15 | 2 wrapped, 1 cable replaced | | Degraded door seals | 2 of 15 | Gaskets replaced | | RCD at upper trip limit | 1 of 15 | Logged for monitoring | | Firmware out of date | 15 of 15 | All updated |
Of the 15 chargers, 13 were fundamentally sound and required only routine maintenance. Two had faults that would have become safety issues if left unaddressed — the loose terminals generating heat and the degraded contactor. The communication fault on charger 12 was a reliability issue rather than a safety concern, but it had taken that charger out of service entirely.
What the Building Management Got Back
After the two-day service:
- All 15 chargers operational — including the two that had been out of service or intermittently faulting
- Full test documentation — a detailed service report for each charger, including test results, thermal images, remedial actions and recommendations
- Updated firmware across the fleet — all units running the latest manufacturer software
- A clear maintenance log — essential for the building's compliance file and for demonstrating duty of care to tenants and insurers
- Next service date scheduled — we recommended continuing with an annual service cycle, with the RCD on charger 3 flagged for re-test at six months
Why Scheduled Servicing Matters
The Princess House service illustrates a pattern we see across every multi-charger commercial installation that reaches the two-to-three-year mark:
Connections loosen. Every electrical connection experiences thermal cycling during use. Over thousands of charge cycles, terminal screws back off by fractions of a turn. The resulting increase in resistance generates heat, which accelerates further loosening. Left unchecked, this leads to overheating, insulation damage and ultimately fire risk.
Contactors wear. Charger contactors switch tens of amps thousands of times. The contact surfaces erode with each switching event. A charger that works perfectly for two years may start dropping sessions in year three as the contactor degrades past its reliable operating threshold.
Software falls behind. Firmware updates address security vulnerabilities, fix bugs and improve compatibility with new vehicle models. A charger running three-year-old firmware may develop charging compatibility issues with newer vehicles and may have unpatched security weaknesses in its network stack.
Small problems become big ones. A cable with minor sheath wear is a quick repair. A cable with exposed conductors is a safety hazard that takes the charger out of service. A loose terminal caught early is a five-minute re-torque. A loose terminal that overheats and damages the charger's internal PCB is a full unit replacement.
The IET Code of Practice for Electric Vehicle Charging Equipment Installation recommends annual inspection and maintenance as a minimum. For high-utilisation commercial installations like Princess House, we recommend annual full services with a six-monthly visual inspection.
Manchester Compliance Can Help
Manchester Compliance installs and services EV chargers for commercial buildings, car parks, apartment blocks and workplaces across Greater Manchester. We service all major charger brands and hold manufacturer-approved service credentials. Whether your chargers were installed by us or by another contractor, we can carry out a full inspection, service and certification.
Call us on 0161 706 1360 to book a service, or email hello@manchestercompliance.co.uk.
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