New Wiring and Rewiring Questions New Wiring and Rewiring Questions

Q. I'm trying to refinish a room in our basement. I tore down the ceiling tiles to reveal two clunky '50's-era light boxes. The light boxes contain space for two 24" fluorescent bulbs. One box works, and the other has a rat's nest of wires and no bulbs. The house has the original 1951 electric with glass fuses. I can't replace the whole thing now, so I'm hoping to replace the two light boxes in this room. Do you think I could find a local electrician to come in, pull out the existing light boxes, and put in new ones without rewiring the room? Can I buy two new lighting fixtures and have an electrician install them, or does he have to see it and tell me which type to buy?

A. Contact the electrician first. Then you should be able to go ahead and buy the fixtures before he comes. Buy the fixtures that please you, and when he sees them he will know the appropriate boxes to install. An electrician ordinarily will not put in a box and then tell you what kind of fixture to buy. Lighting is a very individual thing, and the owner's intention, whether functional or aesthetic, is his choice. There are boxes for all lighting types, and the electrician will probably have a variety in his truck, one of which will suit your needs. This should be a relatively inexpensive job for a pro to do.

Since he is only changing the boxes, he is not modifying your circuit. It is generally assumed that existing original house circuits, not necessarily circuits which were modified by a previous owner, were to Code at the time they were installed, and if you do not modify them, they are not required to be brought up to the latest Code, and are grandfathered. If you are just replacing light fixtures where existing light fixtures were installed, as well as replacing bad switches, receptacles, and other existing devices, you are not required to upgrade, or rewire, the entire circuit.

Q. My house was built in 1961. All the receptacles in the bedrooms are fed with cable of a black and a white wire, no ground. I really need to ground the receptacles in my bedroom where I use my computers. Recently I upgraded the service with a 200A panel. An electrician installed the ground system with one rod driven into the ground right below the new panel. From here, one #4 wire goes to the panel; another #4 wire goes through the attic and is tied into the copper water pipe where it (the water pipe) entered the house. Both ground wires are protected and the whole job was inspected by the city. I am thinking of splitting the #4 ground wire in the attic, wire nut and put it in a j-box. Then I will try to fish a #12 green wire from the receptacles in my office to the attic and pig tail it to the #4 ground wire in the j-box. Is it OK to do this way or is there an easier way?

A. The best thing to do would be to install a new-grounded receptacle on a new circuit just for your computer. With your 200A panel, you should have plenty of breaker slots open for a circuit. The #4 wire to which you refer is called a Grounding Electrode Conductor. You are not permitted to use a wire nut on it. You may attach your outlet Equipment Grounding Conductor to it, but you must do it without cutting it.

Q. I'm a reasonably good handy man but I can't remember how to wire a double outlet. Single outlet, no problem, and double - well, let us just say it wasn't the way I remember. I know one of the outlets get the hot and one of them get the negative and the grounds all go together. But the wire between the two outlets is what is confusing me. Is it hot to hot and negative-to-negative or is it unused negative to unused hot?

A. By the way, there is no negative wire. It's called a neutral. The hot wire is both negative and positive. Pretty much any outlet has two sets of screws on both sides, precisely so something like what you're trying to do can easily be done. After you hook up one of the outlets to the power supply cable, run a small length of cable from the supply outlet (using the second set of screws that are there) to the second outlet. That's one of the reasons the other screws are there. Keep black-to-black, white-to-white, and ground-to-ground. That will leave more room in the box than pig tailing every wire. You'll still probably have to pigtail the ground (bare) so that both outlets can be properly grounded or use a grounding wire nut that has a hole in it, allowing one wire to poke through, saving the need for one of the pigtails.

Q. Is it accepted practice to mount a junction box to the bottom of a floor joist in the basement ceiling? My alternative would be to mount the box to the side of the floor joist and have the j-box cover plate be flush with the bottom of the joist. I have existing j-boxes that are mounted to the bottom of the joists and that seems to be the easiest route. Are there any other do's/don'ts that I should be aware of when installing a j-box?

A. It is common practice to mount the junction box to the side of the joist, but code does not prohibit mounting it to the bottom of the joist if you prefer. I don't see why you would prefer to do so. Most boxes are designed to be nailed to the side of a framing member, and doing so gets them more out of the way and less subject to damage.

Q. I was wondering what the code is and the best practice is when using the white wire on a 2-conductor switch leg. Must the black wire be used for the switched conductor (to lamp) and the white wire be used as the power into the switch? Must the white wire be re-identified with an electrical tape? I would prefer to keep the black wire as always hot and tape the exposed length of the white wire with blue. Can a re-identified white wire be the switched conductor? Should the entire length of exposed wire be re-identified or just a substantial portion? Can I use shrink tubing (or other sleeve) to re-identify the white wire? Must the tubing be UL listed?

A. Code stipulates that the always-hot conductor be the white wire, and that the switched wire be the traditional black. You can re-identify the white wire with electrical tape or with a marker. I suppose you could use shrink tubing, if it is UL approved and rated for ac use. You only re-identify each end; you don't have to re-identify the entire length.

Q. My home inspector found some DIY splices in the wiring in the attic and said that has to be fixed now - he suggested dry boxes at each splice. In addition, none of my GFCI outlets will trip - I know I can replace these myself, but the main box won't open! You have to unscrew it to get to it. Do you think I can do this splice repair myself? I have wired vanity lights, changed out fixtures, etc.

A. The splices can be repaired relatively easy. Depending on the amount of slack at the splice, you will separate the splice, nail an electrical box to a nearby joist or stud, and remake the splice in the box with a blank cover. The code requires 6 inches of slack in the box, so you may have to place a box further "upstream" in the circuit 6-8 inches in order to provide 6 inches of slack in each box and add additional wire or cable to make it to the original splice location. Non-metallic - you can use plastic Non-metallic cable-connectors that "snap" into the ½ inch. The KO's on the sides of the O-B. There is a connector-size that will accept two 2-wire cables in one connector.

Q. I have a breezeway with a pitched roof that connects my new addition to the old part of the house. The problem is, it is so dark and hot, and the owners installed a mini fan with two touch light fixtures on either side, one of which doesn't work. I am only 5'2" and cannot reach this stupid touch light that doesn't turn on with any switch. My guess is, I could remove both of these useless lights, cover the exposed wires, shove them back into the hole, leave the fan in place and add Solar tubes to either side of the slanted walls for additional light. Can that be done? Or should I just replace the lights with better fixtures and figure out how to get a switch to turn them on?

A. Visit your public library or home center and pick up a few books on home wiring. The books will explain what's involved. Be careful about just pushing wires back into the wall. If not done properly, it can be a safety hazard. Have these lights wired to a pair of 3-way switches, one at each end of the breezeway. Then replace the touch lights with regular lights. Another possibility that would be much simpler to wire is simply to replace the fixtures with motion/photocell activated fixtures.

Q. As I remodel my kitchen, I cut a 50-year-old NM 12/2 wire in order to move it, and then reconnected it inside a metal junction box. I used simple, yellow wire nuts to connect black-to-black, white-to-white, ground-to-ground, but I didn't connect a ground wire directly to the junction box. As I used my voltage detector pen, I found that every part of the junction box gave a signal! Of course, the black wire was hot while the white and ground wires were not hot. There was no damage to the 12/2 wires, and it was firmly attached to the junction box using 3/8-inch clamps. Then, when I finally pigtailed a ground wire from the junction box to the ground wires from the incoming and outgoing ground wires of the 12/2 cables, the signal from the junction box completed disappeared! Why did this happen? Did I make a mistake, and is it dangerous?

A. If you were reading something from the BOX, it was more than likely random voltage from nothing to give the circuit a baseline reading for your tester. What you need to do if it was a simple splice is reconnect in the manner you did and now check from the HOT wire to the ground. You should have voltage, now from the BOX to the HOT you should have voltage.

Q. I am installing a new range hood. I had an electrician do the wiring through the wall. There are three wires from the wall: bare copper, black, and white. There are three on the hood: two whites and one black. I'm assuming the bare copper is a ground, correct? How do I know which wires connect to which?

A. Just go color for color. The two whites go to the one white from the wall. The ground gets looped under the green screw, and black to black. Be sure to use a proper connector on the cable coming out of the wall.

Q. I am in the process of finishing up framing on my basement and moving on to planning the electrical. Is there an online site that can tell me how many outlets, lights, etc. I can put on a circuit and other things, such as, does the powder room needs it own circuit?

A. The fact that it's a basement makes no difference. A finished room is a finished room. A bathroom is a bathroom. This is not something we can just tell you all the codes you need to know. The NEC is huge and much of it pertains. If you really don't know anything about residential codes, I suggest you read several good books on the subject. A few folks on here have names for you as to which ones are good.

Q. When I get my roof redone, I am going to remove my two attic fans and have just a ridge vent installed. The fans are wired to a switch in my hall and wired to what appears to be a dedicated 20-amp circuit. I would not mind at all leaving the wiring in the attic in case I decide to use it for lights or some other thing in the future. Is there a way to terminate the two wires safely and then just leave the switch off?

A. Mount an electrical junction box to a framing member where the fans used to be. Feed the ends of the wires into the box and cap each wire separately with a wire nut. Then put a blank cover plate on the box. You might even want to write a note on the cover plate or the framing member with a Sharpie telling what this used to be used for. Staple the cable (not too tight) to a framing member about 6 inches outside the box.

Q. I'm planning on installing an in-ground pool and doing as much of the work myself as possible. I know I have the underground feed for the detached garage running right through where I intend to put the pool. I pulled the cover off of the conduit where it enters the attached garage and I can see three wires. What are my options on how to relocate this run? Is there a way to kill the power, cut the wire and then splice on an extension to not have to disconnect anything from the panel?

A. Yes, you could install a junction box and connect new wires. However, to fully consider your options please provide some additional information.

Q. If I switch the location of the refrigerator with an electric oven, must I move the power box for the oven to new location? Of course, I will use j-box if needed and run new wires to new location. This is a dedicated 220V circuit for the oven. Is it considered an upgrade in kitchen? If it is, then do I need to upgrade all other circuits in kitchen to meet the codes?

A. New cabinets and new countertop might mean you need to bring the electrical up to code. It depends on the inspector. Moving circuits is probably not considered an upgrade to the kitchen. However, if you run a circuit for the refrigerator, you will need to make it up to code. More importantly, you will probably have to make the new run for the stove up to code, which means a four-wire circuit. The existing circuit may only be three wires, which is no longer allowed for new installations.

Q. I am trying to add an outlet on a circuit controlled by two three-way switches. The first switch is located on the ground floor; the second switch is located on the second floor. I want to add the outlet below the second switch, so I can add it between the switches or after the second one. I cannot, however, figure out how to wire it so that it is always hot. Am I missing something here? Or can this not be done the way it is already wired?

A. Not counting ground wires, if you only have three wires in the switch box, you cannot do it for sure. If you have five wires in the box, you can do it, but the receptacle might be switched. It would only be possible if the neutral wire goes through the switch boxes and if this switch has the always-hot side of the power as opposed to the switched hot side of the power.

Q. I need to install a sub panel in my home to allow for additional circuits (basement remodeling, power tools in expanded woodworking shop, etc.). From other threads I understand that I would use a 240V breaker in the main panel to feed the sub panel, the neutral/ground bridge in the sub-panel should not be connected, and the sub-panel should not be grounded directly to a water pipe. I have a three questions that I didn't find answers to:
1. The main breaker in the primary panel is 200 amps; how large (power load) of a sub panel can I install? I live in DuPage County, Illinois; not sure but think the 1999 NEC is still our guideline. Second hand information says a sub panel cannot exceed 60% of main panel master breaker rating, but I don't know if this is reliable information.
2. Do I install a master breaker in the sub-panel as well? In other words, wire from the 100 amps "feed" breaker in the main panel into a 100 amp "master" breaker in the sub panel?
3. I will be connecting the sub panel to the main panel using conduit, so I don't think I need to pull a separate ground wire; agree?


A. 1. You can make the sub panel as large as you want it (in theory anyway).
2. This depends on the size of the sub panel. With a large enough panel, you need a main breaker. With a small panel, you don't need a main breaker.
3. You need to run four wires from your main panel to your sub panel. Two hot wires, a neutral and a ground.

Why do you think you need a sub panel? How many new circuits do you plan to install? How many open spaces are in your main panel? How many breakers are presently in your main panel, and are any of them tandem breakers?

Understand that a sub panel may be the best way to go, especially if the distance is not short from the main panel to the woodworking shop, but if you intend to put the sub panel right next to the main panel, you should be certain that you really need it.

Q. I am planning to put 12VDC LED lighting in a passive basement wine cellar for low heat, low UV emission, and possible direct future solar panel usage. What is the code for DC wiring in ceilings/walls? I was planning to wire them to a single junction box, with a transformer and rectifier to switched 120VAC for now, with the option to connect to a solar/battery system later.

A. There are not that many codes for low voltage. Usually you just want to keep it away from line voltage stuff. Most of the codes are what you cannot do such as run the cable through the furnace ducts unless the cable is rated for such. The wire should still be rated for in-wall use. I find in-wall speaker cable good for DC applications if the current draw is not too high.

Vist our Electrical and Electronics Forums to get your own electrical questions answered.

Got a New Project You're Proud of?

Post it on Your Projects!