Mike Dolt Enterprises
Mike Dolt Enterprises
User: mike33, Location: Irvine, CA
Asked on: Thursday, April 28, 2011 at 1:21 am EDT
Answered on: Tuesday, May 14, 2024 at 4:43 am EDT
Question: The neutral bus in a Jandy sub panel melted. Was replaced by others. Then melted again. Then we were called. I personally have not seen it yet, but I trust the source describing it as melted. This panel feeds all the pool equipment. The HO says the problem only happens in the rain. No breakers tripped. The neutral supplying the sub panel was checked and is tight.Any ideas of what could cause this? Could the neutral wire between the main panel & sub be damaged? Maybe shorting to ground?Related?.... There is no cold water bond and the #6 copper ground wire ufer was very loosely connected to the #4 from the panel.
Potential Causes
Damaged Neutral Wire
It's possible that the neutral wire between the main and sub panel has been damaged, causing a short circuit to ground. Rainwater could be penetrating the wire insulation and causing this issue.
Improper Grounding
The loose #6 copper ground wire ufer and lack of a cold water bond indicate improper grounding. This could be contributing to the problem.
Ground Fault in Pool Equipment
A ground fault in any of the pool equipment connected to the sub panel could cause the neutral bus to melt. Rainwater could exacerbate the issue by creating a conductive path.
Overload
If the pool equipment is drawing excessive current, it could overload the neutral bus and cause it to melt. Rainwater may increase the load by creating parallel paths for current to flow.
Troubleshooting Steps
1.
Disconnect the pool equipment
Turn off the breakers or disconnect the equipment from the sub panel.2.
Visually inspect the neutral wire
Check for any visible damage or corrosion along the wire between the main and sub panel.3.
Test the ground connections
Ensure that the #6 copper ground wire ufer is securely connected to the #4 wire from the panel. Install a cold water bond if one is missing.4.
Measure the neutral current
Use a clamp meter to measure the current flowing through the neutral wire under both dry and rainy conditions. Excessive current may indicate a fault.5.
Isolate the faulty equipment
If the current measurement indicates a fault, disconnect each piece of pool equipment one at a time until the neutral bus stops melting. This will help identify the faulty device.
Additional Considerations
Rainwater Penetration
Ensure that there are no cracks or gaps in the sub panel enclosure that could allow rainwater to enter.
Equipment Age
If the pool equipment is older, it may be more susceptible to ground faults.*
Electrolysis: In the presence of moisture, electrolysis can occur at the ground connection, weakening the bond and potentially leading to a ground fault. Flag for review