I would bet someone over torqued it.Environment, excessive moisture, improper torque.
Agree.I would bet someone over torqued it.
How does excessive torque cause corrosion?I would bet someone over torqued it.
Likely not the corrosion directly with the over torque but in combination with the over torque compromising the conductors then a little more heating of conductors than would be expected because of the compromised conductors, it would accelerate corrosive effects leading to additional heating and further compromising it becoming a viscous cycle and eventually leading to the conductor total failure. All depending on loads applied to the conductors and initial damage by how over torqued the connection was made.How does excessive torque cause corrosion?
What would cause CU conductors to corrode so badly they severed from the Polaris terminal blocks inside a J Box on a roof?
That is what everyone says, however I don't think in my 24 years doing this I have ever seen a connection fail from excessive torque. Just because I have not seen it, doesn't mean it doesn't exist of course, but it must be extremely rare.Over torqued is just about as bad or maybe worse as under torqued.
Interesting. Hadn't thought of that aspect at all.Was this a solar installation, and if so were the conductors carrying AC or DC?
If it is DC and the connection was sufficiently poor to cause at least a few volts drop, then that might greatly accelerate corrosion because of electrolysis. This is assuming that at least some moisture was present. And as the corrosion proceeds the voltage drop would increase, which then increases the rate of the corrosion, further increasing the voltage drop, etc., ...
I was kind of thinking the same thing, but wouldn't that require water/electrolyte for that to happen? Maybe the box leaks or does not drain properly?Was this a solar installation, and if so were the conductors carrying AC or DC?
If it is DC and the connection was sufficiently poor to cause at least a few volts drop, then that might greatly accelerate corrosion because of electrolysis. This is assuming that at least some moisture was present. And as the corrosion proceeds the voltage drop would increase, which then increases the rate of the corrosion, further increasing the voltage drop, etc., ...
It's hard to say; were the Polaris blocks' lugs the right size for the conductors? Overtorqueing, undertorqueing, wrong size lugs, anything that introduces resistance generates heat, and heat accelerates chemical reactions. Also, heat damage and corrosion are difficult to tell apart, and often there are both. Sometimes heat will melt strands, which increases resistance, which generates more heat, which melts more strands, which runs away until the conductors are completely severed. The common denominator is resistance heat.What would cause CU conductors to corrode so badly they severed from the Polaris terminal blocks inside a J Box on a roof?
I cut the Polaris connectors off and used wire nuts instead. Ironically.
It cuts the strands.Not saying it doesn't, but how does over-torqueing an otherwise correct connection increase resistance? Seems like it should lower the resistance.
Exact same thing happened to me. It was a can in the sun. The connector basically melted due to a loose connection. I made the connection myself, and when I picked it apart and found the conductor, it was over-torqued. Some conductors were a little flat.What would cause CU conductors to corrode so badly they severed from the Polaris terminal blocks inside a J Box on a roof?
I cut the Polaris connectors off and used wire nuts instead. Ironically.
Which adds resistance, which adds heat, which compromises more strands, which adds more resistance, which adds more heat...It cuts the strands.
Ah, that's not simply over-torqued and I wouldn't call it such; that's flat out strand damage. For a spec of 400 inch-pounds (33.3 ft-pounds), cranking to 500 is 25% over but probably isn't going to break any strands. OTOH double-torque might well damage the strands.It cuts the strands.
One thing that overtorqueing can do, especially if the wire is near or below the range of gauges the lug is made for, is to spread out the strands so that some of them do not participate in the connection. Resistance, heat... off to the races.Ah, that's not simply over-torqued and I wouldn't call it such; that's flat out strand damage. For a spec of 400 inch-pounds (33.3 ft-pounds), cranking to 500 is 25% over but probably isn't going to break any strands. OTOH double-torque might well damage the strands.
Or, there's over-torque and there's gorilla-arm massive over-torque damage.