In Merrick, the panel tells you the decade
On older Merrick blocks the electrical system is often the honest historian of the house. Lou opens the readily accessible panel covers on every inspection — New York requires it (19 NYCRR 197-5.9) — and what is behind the door is where Merrick findings have concentrated — water damage reaching a main breaker, a breaker carrying two circuits under one lug — the kind of thing only visible with the cover off.
Heating runs a close second. Chimneys and flues that served an oil boiler for fifty years have usually been converted, re-lined or abandoned somewhere along the way, and which one happened is worth knowing before closing rather than after.
Related: Old wiring and panels, explained · What an inspection costs · Schedule an inspection.