ECN Forum Forums General Topics of the Trade General Discussion Area New panel to replace zinsco, replace round meter

I would observe that this Square D model has the mast enter dead center of the top: SO1020M100S . It's probably no wider than the existing panel.

The only 'if' is that it is a 100-amp service. There may be larger models available with a similar arrangement.

Note that a new service will need a new, larger mast, in any event. "Mast location" is going to be a bit different no matter what.