Electrical: Is this tangle of wires in a 100 year old house cause for concern?

Question

Just bought a 100 year old house and it has knob and tube wiring along with newer wiring running to the kitchen and parts of the finished basement. There's a whole bunch of wires in the basement. I'm not sure what is still being used, or what isn't and is just old that was left in place.

There's a couple places where a bunch of different wires are all tangled and connected together, seen in the photos below. Is there anything I should be looking for? Any cause for concern? The inspector didn't mention anything about it during the home inspection.

Answer 1

The first photo shows home telephone wiring.

One of the cables is the two-conductor service wire from the phone company. It is most likely the black cable passing through the knob insulator, but it could be that very old cloth-insulated three-conductor cable caught between the subfloor boards. You may be able to trace it to where it comes into the house, and you can see if it continues on to a utility pole.

The remaining wires are all runs to various and sundry phone extensions throughout the house. The photo shows samples of every type of house internal phone wiring ever used from 1920 to 1990. Look around the house for phone jacks; you probably have samples of those spanning 70 years also.

The inspector didn't say anything because the wiring is completely safe, even it it's still connected to the phone company.

Depending on where you are, if you can find a suitable telephone to use, you may be able to make local emergency (e.g. 911) calls even if you are not a subscriber.

The second photo could be of anything.

If the inspector didn't go into cardiac arrest, it must be low voltage and therefore safe. It's most likely for your doorbell.

Answer 2

In the first photo, the flat whitish cable with 4 wires inside it is definitely a phone cable. The fat blue one is a CAT 5 network cable, but some of the wires aren't being used. It looks like somebody needed to add a phone line, but only had a CAT 5 cable, so they used that. Unconventional, but I don't see why it wouldn't work.

Answer 3

Agree that the first photo is simply telephone stuff and nothing to worry about.

However, you need to get your hands on a multimeter to better understand what's going on in the second pic. (If it leads back to your phone mess, ignore me.) Maybe that means a quick visit from a real electrician. (Money well spent if you compare it to having your house burn down.)

To step back for a moment, knob+tube is a really robust way to wire a house. Problems occur when people touch it, and I'd suspect a whole bunch more horrible hidden inside the walls based on pic #2.

FWIW, home inspectors are human. Some are great; some are utterly terrible.

Answer 4

I agree that the first picture consists of telephone and CAT5 grade wiring, but I wouldn't summarily dismiss it. Grounding POTS 48V across your heart can stop it (your heart, maybe the current, too), so if it's someplace where that could happen (say via water pooling from a leak), get it fixed/replaced.

The second shows what I would guess to be 16/18ga tying into similar size Romex, normally used for household level voltages/currents. The buttsplice connectors are used inappropriately here; note that you could stick something metallic and pointy in the ends without wires. Highly unlikely, but still, it shows an unprofessional or lazy installation. I'd want to know where they come from and go to before I dismiss them, since this could be the smallest mistake the installer made; what else did they do down the line. And don't forget, just because it reads 0V across them doesn't mean it won't go hot when someone flips a seemingly unrelated switch somewhere.

Answer 5

Following from the answers regarding the first photo and telephone connections:

There is one thing to worry about in the first photo: your DSL internet connection speed will likely be impacted by so many random telephone wires/spurs. You'll likely get much better internet speed if you get a completely new copper line from the street to a single port for your modem, with no spurs heading off to other rooms etc.