As with most things except maybe wine and scotch deterioration occurs with age, insulating materials dry rot or loose their finish permitting absorption of moisture, metallic parts may rust or change due to heating and cooling over the years. IMO, the only way to make an accurate determination of equipment is to test the equipment and do a thorough visual inspection. Infra red under load then during a schedule outage perform electrical preventative maintenance to include meggering, high current test (If the OCP's are circuit breakers) and ductor/micro-ohm measurements of critical connection and all power contacts.
Even these test can miss some problems such as deteriorated insulators, megger readings taken a during a period low humidity may now show a problem (or how bad the problem is) with the insulating material. This is also possible with newer equipment but as noted with age comes deteroiation.
Other issues also play into this:
Where was the equipment utilized? An environmentally controlled facility or a chemical plant.
Has the available fault current increased and does the existing equipment meet the new fault current levels.
Is the distribution equipment 480/277 VAC? Would GFP be required if installed today?
Ar there any know issues with this equipment?
3 possible options
1. Clean it, perform maintenance and test the equipment, if it passes go for it.
2. Replace it.
3. Leave it, there is a lot of Frank Adams still in use, The switchboards, were solid. Just do not accept any liability for the equipment.
And if this is a single panel, heck replacement won't be that much replace it.
