Maryland has a lot of beautiful old housing stock, and a lot of it is still running on wire that was installed before the second world war. Here is how to tell what you have.
Knob and tube (pre-1950)
Ceramic knobs holding single conductors, ceramic tubes through joists, cloth insulation. No ground. The cloth goes brittle, and because it was designed for open air, burying it in blown insulation traps heat. Insurers increasingly refuse it outright.
Cloth-covered NM (1930s to 1960s)
Looks like modern romex but with a fabric jacket. Often ungrounded. The jacket crumbles at the panel and at every box, which is where the failures show up.
Aluminum branch circuits (roughly 1965 to 1975)
Stamped AL or ALUMINUM on the sheathing. The wire itself is not the problem - the terminations are. Aluminum expands, contracts and oxidises, connections loosen, and loose connections make heat. A full rewire is the permanent fix; approved pigtailing at every device is the budget one.
Two-prong outlets everywhere
No ground means no protection for anything with a metal case and nowhere for a surge to go. Where running a ground is impractical, GFCI protection is the accepted alternative - see outlet and switch work.
What a rewire costs and how long it takes
Whole house rewiring in Maryland typically runs $8,000 to $20,000, driven by square footage, access, and whether we are working around plaster or drywall. A three bedroom row home with a usable basement and attic is much cheaper than a center-hall colonial with finished everything. Most jobs take one to three weeks.
Do you have to move out?
Almost never. We work room by room and keep power live in the parts of the house you are using. Most families stay put the entire time.
Older-home specialists across electrician in Baltimore, electrician in Annapolis, electrician in Frederick and every other Maryland city. Call (888) 592-6466.