Commissioning and Functional Checks for Residential EV Charging

Commissioning mindset: verify, then energize

Commissioning is the set of checks performed after the EVSE is installed and terminated, to confirm it is safe, correctly wired, correctly configured, and performs as intended under load. Treat it as a controlled process: (1) visual inspection with power off, (2) electrical tests before and after energizing, (3) EVSE configuration, (4) functional charging test with a vehicle or test load, and (5) documentation and customer handover.

1) Visual inspection checklist (power OFF)

Start with a systematic walkdown before you energize anything. Many commissioning failures are mechanical (loose terminations, missing bushings, incorrect strain relief) rather than “electrical mysteries.”

Enclosure, mounting, and environment

• EVSE is securely mounted, level as required, and meets any required working clearances.
• Correct enclosure rating for the location (indoor/garage/outdoor) and all unused openings are sealed with listed plugs.
• Cable entry uses proper fittings; no sharp edges; bushings installed; conduit fittings tight.
• Drip loops present where needed; gasket surfaces clean; cover screws installed and tightened evenly.
• No signs of moisture intrusion, debris, or construction dust inside the enclosure.

Conductors and terminations

• Conductors are undamaged (no nicks, flattened insulation, or pulled strands).
• Correct color identification and re-identification where required; no “mystery” white used as hot without proper marking.
• Terminations are fully seated; no copper exposed beyond lugs; ferrules used where required by the EVSE terminal type.
• Torque values: confirm each power termination has been torqued to the manufacturer’s specification (panel lugs, breaker lugs, EVSE terminals). Record the torque spec and method used (torque screwdriver/wrench).
• Equipment grounding conductor landed on the correct grounding terminal; bonding jumpers installed where required.
• Neutral landed only where applicable (some EVSE do not use neutral); no shared neutrals unless explicitly designed and permitted.

Labels and identification (pre-energization)

• Breaker directory updated with “EV CHARGER/EVSE” and location.
• EVSE circuit label at disconnect (if present) and at EVSE (if required by local practice).
• Any required warning labels (e.g., multiple power sources, load management notes) prepared for handover.

2) Electrical tests

Perform tests in a logical order: start with de-energized checks (continuity/insulation), then energize and verify voltages and operation. Use a properly rated meter and follow safe test practices (PPE, one-hand technique where appropriate, stable footing, and controlled probe placement).

2.1 Polarity and voltage verification (energized)

After completing de-energized checks and confirming covers are in place where required, energize the circuit and verify supply voltage at the EVSE line terminals (or at the disconnect/load side if that is the accessible test point).

• Single-phase 240 V EVSE (typical): measure L1–L2 (should be nominal ~240 V), L1–G and L2–G (often ~120 V each in split-phase systems).
• 120 V EVSE (if applicable): measure H–N (~120 V), H–G (~120 V), N–G (near 0 V; small stray voltage may appear depending on conditions).
• Confirm there is no unexpected voltage between neutral and ground at the EVSE that would indicate a wiring or bonding issue.

Step-by-step:

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1. Set meter to appropriate AC voltage range.
2. Verify meter on a known live source (proves meter is working).
3. Measure at the EVSE supply terminals (or disconnect load side): L–L, L–G (and N–G if present).
4. Compare readings to expected nominal values; if out of range, de-energize and troubleshoot before proceeding.

2.2 Ground continuity / bonding verification (de-energized)

Ground integrity is foundational for EVSE safety functions. Verify a low-impedance equipment grounding path from EVSE enclosure/ground terminal back to the service grounding point.

Step-by-step:

1. De-energize and lock out the EVSE circuit.
2. Use a continuity tester or low-ohms meter (preferably with a dedicated continuity function).
3. Test between EVSE ground terminal (or metal enclosure bonding point) and the grounding bar at the panel (or known grounding point).
4. Wiggle-test: gently move the cable/conduit near terminations while observing continuity to catch intermittent bonding issues.

Interpretation: You want consistent continuity and very low resistance. If resistance is unstable or higher than expected, inspect bonding jumpers, fittings, and terminations.

2.3 Insulation resistance (megger) where appropriate

Insulation resistance testing can help detect damaged cable insulation, moisture intrusion, or pinched conductors. Whether it is appropriate depends on the EVSE manufacturer instructions and what equipment is connected. Do not megger through sensitive electronics unless the manufacturer explicitly allows it.

• If permitted, isolate the EVSE electronics (disconnect line conductors from the EVSE input terminals) and test the branch conductors.
• Test conductor-to-ground and conductor-to-conductor as applicable.
• Document the test voltage used and the readings.

Practical note: If you cannot isolate electronics or the manufacturer prohibits megger testing, rely on careful visual inspection, continuity checks, and operational testing instead.

2.4 Breaker operation and protective function checks

Verify that the breaker and any upstream disconnect operate correctly and that the EVSE responds properly to loss of power.

Step-by-step:

1. With EVSE idle, switch breaker OFF then ON; confirm EVSE powers up normally (status indicators, self-test behavior).
2. Initiate a charge session (vehicle connected) and open the breaker; confirm charging stops immediately and EVSE indicates power loss appropriately.
3. Restore power; confirm EVSE returns to ready state without fault latching (unless the manufacturer specifies a manual reset).

If the installation includes a GFCI/AFCI function upstream or within the EVSE, follow the manufacturer’s prescribed test method (test button or app-based test). Record results.

3) EVSE configuration

Many commissioning issues come from configuration mismatches: the EVSE is set to a higher maximum current than the circuit supports, Wi‑Fi is not stable, or load sharing is not enabled when multiple EVSE are present. Configure before the functional load test so the test reflects the final intended settings.

3.1 Set maximum current (ampacity limit)

Most residential EVSE allow setting a maximum output current. This must match the branch circuit rating and the design intent. The EVSE’s pilot signal advertises this limit to the vehicle; the vehicle should not exceed it.

Step-by-step:

1. Locate the EVSE current setting method (DIP switches, rotary selector, internal menu, or app).
2. Set the maximum current to the value specified for this installation (e.g., 32 A, 40 A, 48 A).
3. Photograph or record the setting position and the resulting configured value shown in the app/display.
4. If the EVSE supports “circuit breaker size” selection, choose the correct breaker rating and confirm the EVSE translates it to the correct continuous output limit per manufacturer logic.

Practical example: If the EVSE is on a 40 A circuit and the EVSE allows a 32 A max setting, set it to 32 A and verify during charging that steady-state current is ~32 A.

3.2 Wi‑Fi/app setup (if applicable)

• Connect EVSE to the customer’s 2.4 GHz/5 GHz network as required by the model; confirm signal strength at the EVSE location.
• Update firmware if prompted (avoid updating mid-charge unless manufacturer recommends).
• Confirm the EVSE appears in the app, shows status (Ready/Charging/Fault), and can start/stop a session if that feature is provided.
• Record the EVSE serial number, firmware version, and network name (SSID) used (do not record passwords).

3.3 Scheduling and load sharing

If the EVSE supports scheduled charging, set a basic schedule with the customer (e.g., off-peak hours). For load sharing (two EVSE or EVSE + energy management), verify that the correct mode is enabled and that devices are paired.

Step-by-step load sharing check (generic):

1. Enable load sharing/group mode in each EVSE.
2. Assign group ID/master-follower roles as required.
3. Set group maximum current (total limit) to the intended value.
4. During functional testing, start charging on both units and confirm current splits/limits as expected.

4) Commissioning with a vehicle or test load

The goal is to confirm the complete chain: EVSE advertises available current (pilot), vehicle accepts it, current stabilizes at the expected level, and nothing overheats. Use a clamp meter and, if available, the EVSE app/vehicle display to cross-check readings.

4.1 Confirm pilot negotiation (basic functional confirmation)

When the connector is inserted, the EVSE and vehicle perform a handshake. You should observe a clear change from “Ready” to “Charging” and the vehicle should indicate it is charging. If the EVSE provides a displayed “available current” or “pilot” value, confirm it matches your configured maximum.

Step-by-step:

1. With EVSE energized and ready, plug into the vehicle.
2. Confirm EVSE status changes to indicate connection and then charging (per indicator legend).
3. Confirm the vehicle reports charging and shows an approximate charge rate.
4. If the EVSE/app shows commanded current, verify it matches the configured limit.

4.2 Observe steady-state current draw

After the initial ramp-up, current should stabilize. Measure current on each ungrounded conductor with a clamp meter and compare to the EVSE setting and vehicle behavior.

Step-by-step:

1. Start a charge session with the vehicle at a state of charge that will accept the EVSE’s full output (some vehicles taper at high SOC).
2. Clamp L1 and L2 (or hot conductor for 120 V) and record current after it stabilizes (typically within a few minutes).
3. Record supply voltage at the same time if accessible and safe to do so.
4. Confirm current does not exceed the configured maximum and is reasonably balanced on L1/L2 for 240 V EVSE (they should be essentially equal).

4.3 Check for overheating at terminations

Heat indicates resistance—often from loose torque, damaged conductor, or incompatible termination method. Check during sustained load, not immediately at startup.

Step-by-step:

1. After 10–20 minutes at steady current, carefully feel for abnormal warmth on accessible surfaces (without contacting live parts).
2. If you have an IR thermometer or thermal camera, scan: EVSE input terminals area (external surfaces), disconnect, breaker, and any junction points.
3. Compare similar points (e.g., L1 vs L2 lug area). A noticeable difference between phases can indicate a termination issue.
4. If overheating is suspected, stop charging, de-energize, and re-check conductor seating and torque.

Practical guidance: “Warm” can be normal; “hot to the touch,” discoloration, odor, or repeated thermal alarms are not. Always follow manufacturer limits and local safety practices.

4.4 Document readings and settings

Commissioning documentation protects the customer and the installer and speeds future troubleshooting.

• As-left EVSE max current setting and any load sharing group limits.
• Voltage and current readings under load (with time stamp).
• Any firmware version and network connection confirmation (if applicable).
• Photos of panel labeling, breaker, EVSE nameplate, and configuration setting method (DIP/selector/app screen).

Troubleshooting trees (field-ready)

Use these quick decision paths to isolate common failures. Always start with safety: if there is burning smell, visible damage, water intrusion, or repeated tripping, de-energize and inspect before further testing.

A) No power / EVSE dead

EVSE dark / no indicators → Check upstream power path in order: 1) Breaker ON? 2) Breaker output voltage present? 3) Disconnect (if any) ON and passing voltage? 4) Voltage at EVSE line terminals correct? 5) EVSE internal fuse/PSU (if serviceable) / manufacturer reset procedure

• If breaker is ON but no voltage at breaker output: suspect breaker failure or supply issue.
• If voltage at breaker but not at EVSE: suspect open conductor, loose lug, failed disconnect, or damaged cable.
• If correct voltage at EVSE input but EVSE dead: follow manufacturer diagnostics; check for internal fault codes; consider warranty/service.

B) Immediate trip when plugging in or starting charge

Trip occurs immediately → Identify what tripped: branch breaker? GFCI device? EVSE internal protection? → Then isolate: 1) Trip with EVSE idle? 2) Trip only when vehicle connects? 3) Trip only when charging starts?

• Trips with EVSE idle: suspect short/ground fault in supply wiring, incorrect line/neutral/ground connections, or damaged insulation.
• Trips when vehicle connects (before charging): suspect wiring error at EVSE terminals, ground/neutral issue (for 120 V units), or EVSE internal fault.
• Trips when charging starts: suspect overcurrent due to misconfigured EVSE max current, defective breaker, or a fault detected under load.

Action steps: de-energize, re-verify terminations and conductor identification, confirm EVSE max current setting, then re-test with vehicle. If GFCI-related, follow the EVSE and protective device compatibility guidance and manufacturer test procedure.

C) Intermittent charging (starts/stops, random faults)

Intermittent behavior → Determine pattern: time-based? temperature-based? Wi‑Fi/app-related? vehicle-specific? → Check: 1) Loose termination/thermal expansion 2) Voltage sag under load 3) EVSE firmware/app issues 4) Load sharing misconfiguration 5) Connector/cable damage

• Measure voltage during charging; significant drop may cause EVSE/vehicle to pause.
• Re-torque terminations (de-energized) if heat-related symptoms appear after 10–30 minutes.
• Try a second vehicle or a known-good test load if available to separate EVSE vs vehicle behavior.
• If load sharing is enabled, temporarily disable to see if stability returns (then correct configuration).

D) Communication errors (app offline, pairing fails, load sharing not syncing)

App/communication error → 1) EVSE has power and is in Ready? 2) Wi‑Fi signal strength adequate? 3) Correct band (2.4/5 GHz) and password? 4) Firmware up to date? 5) Router settings blocking? 6) Cloud outage?

• Confirm EVSE can charge without app control (basic function) to separate “charging” from “connectivity.”
• Relocate or add Wi‑Fi coverage if signal is weak at the garage/outdoor location.
• For load sharing, verify all units are on the same network/mode and group limits are set correctly.

E) Overheating alerts / thermal derating

Overheat alert or EVSE reduces current → 1) Confirm actual current vs setting 2) Inspect connector and cable for damage 3) Check terminations for hot spots 4) Verify enclosure ventilation/ambient temperature 5) Consider reducing max current if required by manufacturer/site conditions

• Use thermal scan to compare breaker, disconnect, and EVSE entry points; a single hot lug often indicates a termination problem.
• If the connector handle is hot, inspect for worn contacts, contamination, or mechanical damage; replace per manufacturer guidance.
• Confirm the EVSE is not installed in direct sun or near heat sources beyond its rating; verify clearances around vents.

Customer handover items

Labels and documentation to leave on site

• Panel directory updated and legible; EVSE circuit clearly identified.
• Any required labels at EVSE/disconnect (circuit rating, load management notes, emergency shutoff location if applicable).
• Commissioning record: as-left max current setting, measured voltage/current under load, date, and installer contact.
• EVSE manual/quick-start guide and warranty information.

Operating instructions (show, then let them try)

• How to start/stop a charge session (plug-in behavior, app start/stop if used).
• Meaning of indicator lights and what constitutes a fault vs normal standby.
• How to use scheduling (off-peak) and how to override it for immediate charging.
• If load sharing is installed, explain that current may vary depending on other loads/other EVSE sessions.

Maintenance guidance (practical and homeowner-friendly)

• Keep connector clean and dry; do not use damaged cords/connectors; store the handle in its holster.
• Periodically check that the EVSE mounting remains secure and that the cable jacket is not abraded.
• If nuisance trips, overheating alerts, burning smell, or discoloration occur: stop using the charger and call for service.
• Wi‑Fi/app: if the app shows offline but charging works, treat it as a connectivity issue; if charging fails, treat it as an electrical/fault issue and contact service.