[Ron1000]

If you're keen on the chocolate block idea. Look up weidmuller they do industrial terminal strips. Much better than chocolate block and you can get them with screws or clamps. Are you crimping the ends of those wires?

Or another option might be an ampseal male plug to female socket arrangement.

Personally I prefer the traditional route of in-line solder and heat shrink or at least bullet and butt connectors that can pull apart, which could also be heat shrunk over.

It would be nice to run the cable though a gland going into the box rather than those gromits, Glands provide a better method of strain relief and if you fit an 'IP rated washer' you can get nice water tight seal. If you do go to glands i'd recommend a threaded entry hole and lock nut, serrated washer on the inside due to the vibration it's likely to take.

On the earth bar RS Components do small earth bars that a pre-drilled and look very neat. Might be ideal for you.