Arc Fault Lockout

Symptoms

The Arc Fault Lockout alert is triggered in the following scenarios:
  • Arc Fault algorithm detects an arc and trips the PV Disconnect
  • Powerwall 3 experiences five Arc Fault alerts within 24 hours

Once this alert has been triggered, a comprehensive inspection must be performed to identify and remediate the issue(s) causing the alert. The following system components must be inspected:

  • System stringing
  • Powerwall 3 wiring
  • Solar junction boxes
  • DC Connectors

Required Tools

  • Thermal camera

Open a Arc Fault Tesla One Form

  1. Add the appropriate Arc Fault form to the job in Tesla One:
    1. Select the job from the schedule and select +Add form.
    2. Search for and select ROW - Arc fault and Ground fault troubleshooting and checklist form
  2. Complete the form as you complete the following troubleshooting steps, uploading screenshots and/or photos as potential causes are ruled out. If Install Support is required, they will use these screenshots to verify the steps that have been ruled out and can be skipped during the call.
Informational PurposesAn informational icon, calling your attention
Note
The Arc Fault form acts as a checklist for the troubleshooting procedure. Follow the steps in the form to complete the troubleshooting process with no additional instructions required.

Inspect the Powerwall 3

  1. On the Tesla One landing page, select Stop System.
  2. Safely shut the system down:
    1. Turn the Powerwall 3 switch OFF to shut the system down, then turn the integrated DC isolator OFF.
    2. Open the Powerwall 3 AC circuit breaker.
    3. Wait 30 seconds before proceeding with any work.
      Warning IconA warning icon, calling your attention to a possibly risky situation
      Warning
      Risk of electric shock from stored energy. Wait 30 seconds after disconnecting all sources of supply before proceeding.
  3. Perform Lockout/Tagout to secure the system against being re-energized.
    Warning IconA warning icon, calling your attention to a possibly risky situation
    Warning
    Confirm Powerwall 3 is de-energized before investigating any wiring.
  4. Inspect the Powerwall 3 PV wiring:
    • Confirm that none of the following components display signs of overheating:
      • DC isolator
      • Conductors
      • PV sidecar (the black and gold terminal box below the DC isolator)
    • Confirm that PV string conductors are properly crimped in the forked terminal, and are fastened with the appropriate torque in the DC isolator. Perform a tug test on each conductor to confirm adequate torquing.
    • Perform a tug test on the wires located between the DC isolator and the PV sidecar (6 wires with color red, orange, yellow, blue, purple and black).
    • Check all wiring to ensure there are no nicks or cuts in the insulation that might create a short with the ground.
  5. Take photos of the Powerwall 3 serial number via the Device Setup interface vs. the serial number on the actual sticker in the enclosure to confirm they match.
    • If the serial numbers do not match, look for other units to confirm you are connected to the correct network and are configuring the correct unit.
    • If the serial numbers do not match and there are no other units, or if you have confirmed you are connected to the correct unit, contact Install Support to fix the discrepancy.
  6. Take a pullback photo of the Powerwall 3.

Inspect Wiring on the Roof

  1. Verify all strings are connected as outlined in the planset and string diagram.
  2. Perform a tug test on all vulnerable connection points, including panel-to-panel links, main PV cables from PV array to Powerwall, and junction box terminations.
  3. Inspect all junction boxes to confirm the following:
    • No damaged wiring
    • Jumpers are fully seated
    • No visible signs of overheating
    • No frayed wires or conductors that have been pulled too tightly
  4. Inspect all MC4 connectors to confirm ensure they are fully seated and do not display any of the following:
    • Deformation
    • Bulging
    • Glossy finish or discoloration
  5. Inspect PV modules for any physical damage or surface cracking. Panels must be inspected under load with a thermal camera to identify microcracks generating hot spots.
  6. Mandatory : Provide photo documentation, include clear, timestamped images of:
    • All inspected DC connections and terminations
    • Junction boxes, isolators, and MC4s
    • Any evidence of wear or mechanical/electrical damage
    • Thermal images of the panels confirming that there is no hot spot
    • Images of PV Sidecar in Powerwall 3
  7. See Perform Insulation Resistance Test to Identify Faulty String. Before proceeding with the insulation resistance test, keep in mind the following:
    • Arcing is not a deterministic phenomenon
      • It is not repeatable every single time
      • It depends upon the current being pulled from the string, ambient temperature, temperature of the component that is arcing, etc.
      • If the system does not fault when the crew is on site, it does not mean there is no arc present
    • Third party testers can have different thresholds for fault detection than the ones used by Tesla's algorithm. For Powerwall 3, this means Tesla may detect an arc that a third party meter does not detect.

After identifying and addressing the potential cause of the Arc Fault, retry the self-test by selecting Stop System then Start System. All self-tests should pass to confirm the issue was resolved.