They say to never say never, and never say always. Well, when I do inspections on old homes, I almost ALWAYS have a mish mash of wiring! And why not? Things changed over the decades and certainly the first, and really old product, cannot survive forever. This particular house is just over 100 years old.
This is a knob from the old "knob and tube wiring." Made of porcelain (essentially glass) the knobs were non-conductive and provided a safe base for the wiring which extended throughout the house. And you can see a little sleeve through which the wiring was run through floors and walls. It was used from the 1880's all the way into the 1930's.
Generally the wiring was run in odd and dangerous areas. It was covered with insulation, had various haphazard repairs and new junctions added by happy homeowners when new wiring came out and new things were to be installed. Such additional work was often unprofessional and unsafe, where the original wiring might not have been.
Insurance companies now routinely ask if your new house has knob and tube wiring! It is considered unsafe due to its age and what I say above. I see it all the time in Virginia. Very seldom, though, do I see it hot!
This is an example of wiring old to "new." A new cable came out in 1916, called the Hochstadter cable, named for its inventor. It included a protective metal and conductive jacket around the cables. The metal jacket was used in many instances as a ground line. Initially used commercially, it became popular for residential use.
Here a "new," what we call, BX cable is used to connect a "new" fixture. The installer broke it apart to create a junction to get power from the older knob and tube lines. You can even see the frayed fabric wrap on the older wiring!
And this wiring is hot! It is still being used to power a single-bulb light fixture, hanging from its original wires, likely installed in the 20's or 30's. It is one of the three lights for this cellar!
How do I know the wiring is hot?
Of course I have a tool!
While you can't see the orange light or hear the beep of my tester, this wiring is hot. The old and the new! And come copper piping right beside and touching everything. While the copper tube is not electrified now, it could be one day!
Sometimes I tease my female clients and ask them to hold my hand while I check to see if wiring is hot. They politely extend their hand and then quickly pull it back, realizing that it could hurt! It gets me a giggle.
I have seen older electricians swipe wiring across the back of their hands to see if it is hot! Hey, why use a new-fangled tool when your hand is available!?
Personally I prefer the tool...
My recommendation: Older houses will have a mish mash of lots of things - electrical, plumbing, paint, flooring and structure. EXPECT that. But also hire a home inspector in INSPECT it! Then you and your clients will know if it is good, bad or indifferent.
Jay Markanich Real Estate Inspections, LLC
Based in Bristow, serving all of Northern Virginia.
Office (703) 330-6388 Cell (703) 585-7560