Old Service Equipment
Let's stick to electrical service equipment, Vintage or/and Obsolete for this "How Do I Know" question.
a. a period of origin or manufacture
b. length of existence: age
c. Too old to be considered modern, but not old enough to be considered antique. Often used to describe items for sale online such as eBay auctions or craigslist posts though may also be found in printed listings such as classified ads. Can also be a euphemism for "heavily used" items.
Vintage; If/when a manufacturer is still producing/making/in the production of/manufacturing service equipment, vintage service equipment becomes the narrative I prefer to use on most/many occasions.
Example; Service equipment parts/devices can be found through the manufacture and reputable dealers most times... but not always.
Obsolete; The manufacturer no longer exists, but you maybe able to acquire service equipment parts and devices for that service equipment due to demand.
Below is a 10 space, 100 amp, GE, General Electric, Combination LOAD CENTER service equipment panel, type (1) box, 120/240 V.A.C. that is no longer being manufactured. GE, General Electric, still manufactures service equipment panels, type (1) boxes, and other service equipment. Electrical Panels are under the name PowerMark Gold, and have more spaces for overcurrent protection devices / circuit breakers.