Wow, open wire fuses! Were these common in Canada, as they were in the UK? I have read that they were used in the USA before 1900, but I certainly have never seen any. Is that real fuse wire, or did someone improvise with a piece of #14 Cu? For that matter, the wires leading in: are they #10 or #8? I guess this would have been a 120/240 single-phase service with a fused neutral, which would make it quite old indeed.
I've never seen 30A receptacles like that, but I do see them listed on page 194 of the 1936 GE Supply catalog.