Any electricians? (knob & tube wiring)

elgecko · #1 06-20-2010, 08:19 PM

So I'm checking out the attic of my 1908 bungalow, scoping venting possibilities for a bathroom fan installation and I find:

Apparently, it's old "knob and tube" wiring...completely alien to me. The house has been upgraded electrically (e.g. all outlets are grounded). The existing light is wired via "modern", multi-conductor wiring as shown. The problem is, there's a branch of old wiring right where the fan housing needs to go (where the multi-conductor wiring crosses the mystery wire).

I'm guessing the knob & tube wiring was left there after the electrical upgrades and is inert, but how do I go about testing it with a multi-meter to confirm?

Thanks!

Steve · #2 06-21-2010, 01:55 AM

What you need is one of those cheap little neon testers.

Hold one on the leads between your fingers and touch the other lead to the wire. if there is any potential in the K&T the neon will glow about half bright.

And yeah, it's safe to do that. I've done it a zillion times and it's about the only way to tell which wire is hot when they're all black.

If it makes you nervous and you're that close to a modern box, you can go across the ground and K&T.

They also make a non contact voltage tester a.k.a. "chicken stick" that's about $15.

FL Knifemaker · #3 06-21-2010, 07:56 AM

It wouldn't suprise me if that's live. I've seen where the line coming into a home is attached to that type of wiring and then run to a modern box

No one likes to work in a hot attic in Florida

L-A · #4 06-21-2010, 08:13 AM

Could it be zealous grounding?

DRafalske · #5 06-21-2010, 12:19 PM

Quote:

They also make a non contact voltage tester a.k.a. "chicken stick" that's about $15.

By far the quickest and easiest ways to go IMO, if you're not familiar or comfortable with working with electricity.

Wouldn't surprise me to find it live either.
I was helping a buddy rehab a house built in 1905 that was full of the stuff. Some disabled and left in place, some live. Since it was such a major renovation anyway, we tore all the old wiring out and redid everything. Lots of knob and tube, and the rest was aluminum.
D

Jim Campbell · #6 06-21-2010, 12:56 PM

Quote:

Originally Posted by elgecko

So I'm checking out the attic of my 1908 bungalow, scoping venting possibilities for a bathroom fan installation and I find:

Apparently, it's old "knob and tube" wiring...completely alien to me. The house has been upgraded electrically (e.g. all outlets are grounded). The existing light is wired via "modern", multi-conductor wiring as shown. The problem is, there's a branch of old wiring right where the fan housing needs to go (where the multi-conductor wiring crosses the mystery wire).

I'm guessing the knob & tube wiring was left there after the electrical upgrades and is inert, but how do I go about testing it with a multi-meter to confirm?

Thanks!

for about ten bucks you can buy a tester that will tell you if it's live...without you having to touch any wires....often when older houses were upgraded some of the old wiring was left,and the only way to know for sure is to test......

if it is just old wire that is not connected to the rest then once you are certain you may remove it.....the nature of that type of wiring makes it difficult to tell as the hot and neutrals often go in different directions......

elgecko · #7 06-21-2010, 02:27 PM

Quote:

Originally Posted by L-A

Could it be zealous grounding?

That was my first thought with all the black insulation but with a little research, I learned it was just old school wiring.

elgecko · #8 06-21-2010, 02:31 PM

I sprung for one of those clamp multimeters. Should do the trick...right?

MJ5150 · #9 06-21-2010, 04:07 PM

Quote:

Originally Posted by elgecko

I sprung for one of those clamp multimeters. Should do the trick...right?

It'll take you one try to find out.

-Mike

FL Knifemaker · #10 06-21-2010, 05:54 PM

I just lick my 9 volts to test them..............

Jim Campbell · #11 06-21-2010, 09:26 PM

Quote:

Originally Posted by elgecko

I sprung for one of those clamp multimeters. Should do the trick...right?

not the same ,clamp meters work on wires with power that goes in one direction,and if there is no current draw on that circuit,there will be no reading.....the "chicken stick" or "tic tester" as it is called here will tell if power is present in a wire......for ten bux.....to use the clamp you will have to use the probes,and if you are not sure about what to do,i wouldn't mess with electricity

elgecko · #12 06-25-2010, 09:43 PM

Picked up a chicken stick, old wiring was not live. Installed the fan with no electrocution, my house didn't erupt in flames, and now I can fart all I want!

kissmybASS01 · #13 06-27-2010, 06:29 AM

Quote:

Originally Posted by elgecko

Apparently, it's old "knob and tube" wiring...completely alien to me.

Ya know...lots of people prefer to have their power fed by tubes. It produces at least twice the amount of juice of newer ss wires. Just sayin is all

FL Knifemaker · #14 06-27-2010, 06:54 AM

Quote:

Originally Posted by elgecko

Picked up a chicken stick, old wiring was not live. Installed the fan with no electrocution, my house didn't erupt in flames, and now I can fart all I want!

I hope you bought a fan that's rated to handle your farts. If the fan motor stops due to the air thickness, that can cause things to burn up as well