[vsheetz]

it appears the breaker bottom right is a 100A 2 pole, ... that should be your 'main breaker' just installed on the wrong side works on the same principal, but it looks like the left side has the hold down kit.

Yes, bottom right is 100a 2 pole main breaker acting as the disconnect. As for being installed on the wrong side, that's the way it came installed out of the box if I recall correctly.

When you say works on the same principle, that's what I was wondering - why would the lower left be called out specifically as backfed space?

Another picture -

 

[vsheetz]

Thanks all to explaining and pointing out what needed correction. Today I moved the main breaker and implemted the hold-down - so it is now as it should be. :thumbsup:

I learn something every day from this most excellent forum! :thumbup: