So, do I just tighten the screw more?

[Richard Moore]

This, to me, is odd. Rare (for here) exterior 200-amp panel. You can see where the main breaker set-screw used to bear on the SEC before it somehow slipped down. The odd bit is it looks like someone tightened the set-screw all the way down after the thing moved, like that would fix it. The home still had power and I was surprised there was no sign of arcing...yet!

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[Ben H]

Hard to think that a SEC slipped. That's a stiff, stiff wire. Had to be pulled somehow?

[Richard Moore]

Yeah, "slipped" probably wasn't the best word I could have used. As you say it probably took tension rather than gravity to pull it out from the lug like that.

[Ben H]

If the lug was semi tight, it would take a good yank one would think. Strange indeed.

[David Meiland]

Possible they just stripped a little too much wire?

[Richard Moore]

Possible they just stripped a little too much wire?

I don't think so. First, I just don't see a sparky stripping that much extra insulation during the initial install. And then, why would there be compression marks on the exposed conductor and how could the set screw be (apparently) bottomed out?

There is one other possibility that just came to mind. The sparky may have cut the cable too short to begin with and the marks are from channel locks as he tried to force the wire into the lug. He failed, but hoped no one would notice his mistake. Whatever...I'm confident it isn't properly secured and needs fixin'.