53 year old duplex, too old as an investment?

[Ally Kumar]

Considering a duplex that is 53 years old, has not had plumbing or electric upgrade. Recent inspection provided by seller indicates minor issues with plumbing and makes note of older electric. Needs a new roof (that was factored into numbers). Numbers work. Its a fair deal not an awesome deal. What are some of the things to consider with older properties? Something to stay away from? What is considered "Old" in real estate world? Pl share your experiences. 

[Max T.]

Devil's advocate - all my properties are in the old city of Philadelphia, all built between 1870-1920. So that would put my newest at close to 100 y/o.

Then again - they have been maintained and upgraded decently well enough prior to my ownership.

Yes I've had to deal with some knob and tube, galvanized plumbing, etc... but not much. 

Do your inspections and make a rational decision based on the actual condition of the property... Age is just a number!