23

Thus far, I've replaced the first receptacle in most of the series of receptacles with an AFCI/GFCI because I'm so confused. Don't do electrical work in a building owned by someone else. To do that you need 2 things: The landlord's permission to do that, for obvious reasons. AND City approval of you doing the job, which normally requires a master ...


11

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, ...


8

Some surge suppressors dump surges to the grounding conductor, some audio video equipment requires a grounding conductor, some "smart" devices trickle current to the grounding conductor, etc. It also notifies folks doing work in this box in the future, that they shouldn't expect to connect the grounding conductor. The label is also applied to all other ...


7

The answer changes depending on location. Because of a complete lack of actual fire incidents, four Western USA States: CA, OR, WA and ID petitioned for an exception to NEC 394.12 and permit insulating over Knob & Tube Wiring. In some places you must first file a Knob-and-Tube Wiring Safety Report, and everywhere else it's a good idea. It is a ...


7

Chase down the matching neutral and remove it. Otherwise it will drive you crazy, and be a loose end of wire unaccounted for. What's more, it could wind up still being in use by some other circuit which shouldn't be there. Part of the reason to fully explore an electrical system is to look for surprises. Besides, since all wires must terminate in ...


6

If you're talking about the equipment grounding conductor, and not the grounded (neutral) conductor, then they may not have to "share" the same equipment grounding conductor. This answer contains all the code references, if you want to give it a read. If your area has adopted the 2014 version of the National Electrical Code, you can share an ...


5

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.


5

For all of the questions you asked: Consult your town's building department (or equivalent if it goes by a different name where you are from). They should be able to pull the permit history for your home if requested and tell you what type of electrical work requires a permit. If you find the that work was done without a permit: If you are solely ...


5

If you can insulate the walls without a "material that envelops the the conductors", then sure. But I would think that wouldn't be a very well insulated wall. Knob and Tube wiring is meant to have an area of free air about it. Insulation encroaching on this space could cause the wiring to overheat. National Electrical Code 2014 Chapter 3 Wiring ...


5

A big problem with K&T is the horizontal runs - sagging over time means stress on the insulation, which becomes brittle from oxidation (not the wire - the rubber insulation), and can break off. You then have (a) bare wire(s). Should those wires come in contact with horizontal piping - particularly after something like a renovation, which usually ...


4

While Tester101's answer was OK when it was written, the situation has changed now. CAFCI/GFCI dual function breakers (Square-D calls them DFCIs) are now widely available online through the big-box stores' websites; in fact, the green box nearest to me has the QO DFCI I linked in stock! Of course, any electrical supply house worth their weight will be able ...


4

You could use "smurf tube" (Electrical Nonmetallic Tubing) or rigid PVC to have a non-conductive conduit. Be sure to bond any metallic conduit that is separated by such non-metallic conduit, or just use nonmetallic the whole way with ground wires. I suspect you are not supposed to contact the K&T in any case and should be securing the wires or conduit to ...


4

Wiring has no business in air ducts, so get it out of there For safety reasons (burning wire insulation in air ducts smoking you out of your house is majorly no bueno), the NEC prohibits wiring in ductwork that isn't required by the HVAC system design in 300.22(B): (B) Ducts Specifically Fabricated for Environmental Air. Equipment, devices, and the ...


4

I see a few common problem areas. Wire function First, there are (were) 4 non-ground wires: black and white from each of conduit and K&T. The lamp only takes 2 wires. The other 2 wires had been previously connected to each other, and you obviously disturbed that. If there are 2 controlled fixtures on this switch I may be barking up the wrong tree ...


4

First off, get yourself a new GFCI with screw terminals and do not use the back-stabs... those are trouble waiting to happen. When you are adding the new receptacle down stream of the GFCI, it is not an extension of the old WIRING, it is an extension of the CIRCUIT. No restrictions there, so even if it is K&T (I also question that), you are fine. The ...


4

The first method (GFCI in lieu of ground wire, subsequent 3-wire receptacles off Load all protected) is perfect. The only thing you need to do, which nobody does, is to label the GFCI to indicate that it has no actual ground and the other receptacles both to indicate that they have no actual ground and to indicate that they are GFCI protected. The second ...


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 ...


3

An AFCI is a great addition to K&T wiring. While the conductors in K&T are separated by large distances, and even studs, they do come together at junction boxes which are often metallic. An AFCI adds a layer of peace of mind to the situation. Be sure to measure your K&T wire to determine gauge. It can take slightly more current than the modern ...


3

You can die from cutting the wrong neutral wire... (but it's not that easy) There is something known as a 3-wire circuit that attempts to take advantage of AC's properties. Intended to let you use a smaller neutral wire than the two hot wires it supports. This is only done for hots sourced from different hot "legs" at the panel. This is supposed to have a ...


3

Plug in an extension cord, and bring its socket end up to where you're working. Measure voltage from extension cord "hot" to the mystery wire. 120ish volts - it's a neutral. Significantly less - phantom voltage on a dead wire. To sanity check what "120ish" volts should be, measure hot v neutral on the extension cord itself.


3

Wow, nice fuse panel. It's well preserved and probably still fully effective. You can only hope the modern panel you replace it with holds up so well! Although we use it all the time, the term "hot" can be a little ambiguous. Keep in mind that voltage is only meaningful between two things. Sometimes when referring to voltage to ground / earth, we'll ...


3

How annoying! OK get a set of drills and start sticking drill bits up through those holes -- butt end first. We just need to know the hole size. Now hit a "Drill and tap" table. Anytime you tap a thread into a hole, you drill the hole to the smaller size (tips of the threads). Go to the table under "Fine thread bolts" and find the ...


3

Consider simply retrofitting ground. This was broadly legalized in the 2014 NEC. You simply run an appropriate sized ground wire from the outlet to any junction box or grounding electrode which has a sufficiently large ground back to the panel. Your idea is "Since neutral and ground is bonded at the panel, therefore neutral is ground". So yeah, ...


3

Yes, GFCIs don't care about safety ground. They do not wire to it in any way. Even in the K&T age, they understood the importance of having neutral wires be monogamous to their partner hot wires. Note there is one legal and safe configuration called an "Edison circuit" or "MWBC" (Multi-Wire Branch Circuit), where 2 hot wires share 1 ...


2

As foreman for a licensed bonded electrician, in San Francisco CA, ca 1980's... K&T wiring was NEC code approved.... and approved by the more stringent local city code... that said I code rewired a lot of Victorian houses, w/ K&T as the original wiring... it could be Western Union, solder-spliced, to repair or extend it... very tedious... and needed ...


2

Code doesn't say that anymore, at least not in WA and OR. Serious study was done on the question of whether blown insulation on K&T was really having an impact on house fires. The studies determined it was not. And so states have been rescinding their laws against blown insulation with K&T. Of course AFCI is a magic bullet that intercepts ...


2

GFCIs are a poor substiture for grounding. Proper grounding should disconnect a fault to the case pretty much immediately. If the case is not grounded A GFCI will only disconnect a fault to the case after your electric shock starts (but hoepfully before the sockhas persisted long enough to kill you) It's better to have a missing ground and a GFCI than to ...


2

The copper wire used in knob and tube has identical electrical behavior to copper wire in any modern cable assembly. Determining the wire type (sheathing around the copper) and cable assembly or use of conduit is something that can only be done visually. Opening up the electrical device boxes (make sure you understand how to work safely on electrical ...


2

There is no electrical or technical way to tell if a box is wired with K & T. You'd get the same results with old non-grounding NM cable. The only way is visual. You'd have to open each box and check with your eyes.


2

I don't know of a tester that'll tell you about wiring type. Your best hope may actually be looking at how wires enter the junction boxes, as well as a borescope in any openings therein. Borescopes are quite inexpensive of late and attach to a phone as their power and display. I would use a plastic-bodied one and turn off the power. What people worry ...


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