At 01:35 PM 4/6/2017, you wrote:
Recently we interfaced with another solar install firm that has gone back to wire nuts due to this same problem.
Wire nuts have the advantage of holding the wires tight with a spring. The spring follows the cold flow of the copper over the years. A screw type connection does not.
When I service an old breaker box, usually the wires are loose under the screw connections, especially on the neutral and grounding bars. Often they are very loose, and I bet that the screws were tight after the initial installation of the equipment.
On old industrial control equipment, I've learned the hard way to tighten all screws before doing anything in the box, as wires are prone to fall out of the loose screw connections. Again, these connections have the weakness of being held by terminal screws, with no spring to follow the cold flow of the metal.
With wire nuts, it can be a bit tricky to know if you have a good connection, as the connection is hidden under the plastic cap. It is good to pull hard on each wire separately to be sure it is securely under the spring. It is crucial never to mix copper and aluminum under a wire nut unless it is one specifically designed for the purpose. Unless specifically listed, all out door wire nuts should be in a weather proof box, and preferably taped.
Drake Chamberlin Athens Electric LLC OH License 44810 CO License 3773 NABCEP Certified Solar PV 740-448-7328 <http://athens-electric.com/>http://athens-electric.com/ --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus
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