Quick Answer
To check for grounding issues before a solar install, inspect the electrical panel, measure the system's voltage, and verify proper bonding at the main service entrance.
Inspecting the Electrical Panel
Inspect the electrical panel for signs of wear, corrosion, or damage to the busbars, neutral bars, and grounding bus. Check that all grounding and bonding connections are secure and not loose. Verify that the grounding electrodes are properly sized and connected according to NEC (National Electric Code) Section 250.64. Use a voltage tester to check for voltage on any grounding point, and verify that there are no signs of arcing or overheating.
Measuring System Voltage
Measure the system’s voltage at the inverter and throughout the array to ensure that it’s within the manufacturer’s recommended range (typically 1% of the nominal voltage). Use a multimeter to measure the voltage, and record the readings. Compare these readings to the manufacturer’s specifications and consult the NEC for any deviations. A voltage drop of more than 3% may indicate a grounding issue.
Verifying Proper Bonding
Verify proper bonding at the main service entrance by checking that the grounding electrode system (GES) is properly connected to the electrical panel. Use a bonding jumper to connect the GES to the electrical panel, and ensure that it’s securely attached. Consult the NEC for specific bonding requirements and ensure that all bonding connections meet these standards. Verify that the bonding jumper is rated for the maximum fault current at the service entrance, as specified in NEC Section 250.64.
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