Residential electrical notes

1. It's better to incur the expense and time to put in 12/2 for circuits where you're not sure they won't be used to do heavy-duty stuff like exercise equipment, a sauna, places where heavy power tools might be used.
2. Never do a home run to a light fixture; always home-run the switch. That way, you'll never have to go looking for power in a light box.
3. Always switch the hot leg. That way, you'll never risk electrocution working on lights when the switch is in the off position.
4. Always suspect heaters, big appliances, electrical equipment, exercise equipment, etc. as requiring a 20-Ampere breaker, especially if there's going to be multiple ones. Typically, modern electronic components like Blu-ray players don't suck much current. However, a good sound system might. If you're powering big speakers with several hundred Watts per channel, that power has to come from somewhere—the somewhere is the amplifier final stage that sucking that much power to do it.
5. Always use the three-way diagram when designing and installing 3-way switches.
6. Always connect or terminate conductors inside a proper electrical box. Use a blank plate to cover the junction especially if you think there's going to be a reason to get inside—usually (but not always) there will be. (Code says, however, that you must not bury it.)

The constants in residential wiring are 110 and 220 Volts. To figure out power or current, use this pie diagram to remember:

P is power (Watts), I is intensity (Volts) and E is energy or current (Amperes). Solving for each variable (this is simple algebra), we get three formulæ:

P = I × E        —to get power (Watts are Volts × Amperes)
I = P ÷ E        —to get voltage (Volts are Watts ÷ Amperes)
E = P ÷ I        —to get amperage (Amperes are Watts ÷ Volts)

You always know voltage (110 or 220). If you have wattage, because it's marked on the side of a product box, you can determine amperage by rearranging the formula above. Let's say you just bought a drill that says 1200 Watts (incidentally, 745 Watts equals 1 horsepower so your drill would be better than 1½ HP):

       P=1200 Watts
________________________
I=110 Volts | E? Amperes

Solving for E (we use the third formula above):

E = 1200 Watts ÷ 110 Volts, so
E = 12 Amperes

This means that, if you're running two drills on the same 15-Ampere circuit at the same time, you'll likely blow the breaker if both drills bog down a little bit at the same time.

I got this this stuff from my father at least 50 years ago and I've never forgot it nor how to use it.

My brother has usually done this for me, however, recently, he has been occupied with his own building project and I have, in addition to a couple of remaining 3-way circuits in my own project, been sort of supervising the wiring of a friend's new home. Consequently, I have had to learn to fly with my own wings. I used to have to look this up every time, but I've got my own favorite solution here.

It is possible to power the circuit by home-running the principal lighting fixture box instead of one of the switch boxes. I personally reject the concept of powering anything except switch boxes for I don't like to find power up in my lights when the switch is off. Doing it that way also prohibits using a dimmer.

Here is how I do it.

I run 14-3 with ground from one switch box through one lighting fixture box and then to the other switch box. I choose one of the switch boxes to run power to and I put a piece of black tape around the 14-3 cable in the other (unpowered) box. Later, after stripping the insulation off the cable to prepare this (unpowered) switch box for inspection, I take the piece of tape and wrap it around the white wire from the cable. This is to show that it is acting as the hot wire in the portion of the circuit between the lighting fixtures and this (unpowered) switch box. It is connected to the common lug of that (unpowered) switch.

The black and red wires in the 14-3 with ground cable flip between powering and not powering the lights. Their color is not really significant, however, hooking the same color to a different pin on each switch, as shown below, creates the case in which the light is off when both switches are in the same state, and on when the switches are in opposite states to each other. This is not the only way the switches can work for it can be set up so that the light is on when both switches are in the same state and off when they are opposite. This is done by cross-connecting the colors in place of how I said to do it here. It doesn't really matter, as an obsessive-compulsive, I prefer it the way I have shown it here.

Of course, as shown, the red and black wires of the 14/3 with ground cable are run straight through the lighting fixture box. It would not matter except for the elegant symmetry of the solution, sometimes very important when you're as befuddled as I am.

So, speaking of symmetry, the only thing asymetrical or bizarre about this solution is that in the lighting fixture box, it is the white lead of the 14/3 cable that acts as both hot and neutral (marked "cold" here in the diagram).

Of course, the grounds are all prepared as normal using green nuts in the switch boxes to unite the two ground wires and tie to the (green) grounding screw on the switch. In the lighting fixture box, depending on the type of fixture (can, fan, chandelier, etc.), a green nut may be used to tie the grounds together with the fixture ground.

In the diagram below, the lighting fixture box is illustrated by the faint dotted line while the switches themselves are not shown in boxes, including the switch where the permanent electrical supply is run. The symmetry to see here is at the "common" lug on the 3-way switch: it always contacts the hot wire—black in the switch box that is home run to the load center and the black-taped white wire from the 14-3 cable that is acting as hot (as marked by the aforementioned tape).

Notes

The white (cold), white (hot), red and black conductors (wires) in the center of the diagram are the 14-3 w/ground cable that runs between the two switch boxes and through one of the fixture boxes (if there are more than one).

At points X, other fixtures to be controlled by the same circuit may be added using 14-2 w/ground. Logically, the connecting cable's black conductor goes to X_b while the white one to X_w , but these are completely arbitrary. Doing it this way makes it clearer.

^* this white conductor should be marked with a piece of black electrical tape to show it's the "hot" conductor to the fixtures.

I purchased a Maxxima MEW OVS100W, 3-way motion-detection, timed switch. This unit is 1- or 3-way capable, but, for 3-way, it normally requires

1. a connection to a neutral,
2. a connection to a distinct and understood hot, and
3. a connection to a distinct and understood load.

In short, it requires a modern, properly wired 3-way switch set-up.

Yet, it comes with instructions for wiring both as a single pole or 3-way installation. As I got into it, I discovered that the 3-way wiring where I wanted it was a Chicago-style, dead-end 3-way meaning that

1. the hot went to the light fixture,
2. one box has a bonafide/guaranteed hot, and
3. the other box is the dead end (no reliable hot or neutral).

The dead end was the one at the position I really wanted for motion detection. Fortunately, however, the Maxxima provides a full 180° sensor.

So, my solution was...

1. to ensure box existing switched worked (they always have for 20+ years),
2. to label all the wires at both ends carefully to explain what each is in case someone ever wishes to restore the original 3-way wiring,
3. to turn the dead-end switch on (turning the light on),
4. to tape up the dead-end switch to protect the electrical connections from being prone to shorting,
5. To force the dead-end switch back, deep into its box,
To cover the dead-end box (containing the switch) with a blank plate because I don't want anyone turning off the new circuit,
6. to wire the Maxxima into the other box as shown below. Basically, my only option is to turn the Chicago circuit into a single circuit. This wiring and its nomenclature is not that of a modern 3-way set-up, but it's how I labeled the wiring inside my box(es).
7. To restore the old circuit, it's only necessary to purchase new 3-way switches, then
   The "dead-end" box:
   1. orient the new switch and carefully wire it in imitation of the existing one (pushed all the way back into the box and, therefore, damaged)
      The "hot" box:
   2. orient the new switch according to the diagram below, then attached the correspondingly labeled wires to its terminals.

Illustration of original box

                      ┌───────────┐
    black (traveler) ├│           │┤ black-taped white (traveler)
[I call it "orphan"]  │           │
                      │           │
                      │           │
                      │           │
                      │           │
                      │           │
                      │           │
                      │           │
                      │           │
                      │           │
                      │           │
                      │           │
              ground ├│           │┤ hot/common black
                      └───────────┘

Note: the two upper screws show here are brass (lighter in color) while
the ground screw is green and the common screw is black.

The Maxxima is wired as below. Note that the labeling here is not as

1. in the diagram above (however, the orientation of the switch is intentionally identical to the diagram above), and
2. in the box, the wires are labeled as above (in case, as already noted, it's ever needed to return to the original 3-way switches); here, I have used traveler 1 and traveler 2 in the same sense as used in modern 3-way wiring diagrams.

Last, please note that the Maxxima's blue lead is capped off (because unused in single pole mode which this is essentially now that I have obviated the dead-end 3-way switch).

Illustration of new box

                      ┌───────────┐
 white to traveler 2 ├│           │┤ red to traveler 1
                      │           │
                      │           │
                      │           │
                      │           │
                      │           │
                      │           │
                      │           │
                      │           │
                      │           │
                      │           │
                      │           │
                      │           │
     green to ground ├│           │┤ black to common black
                      └───────────┘

Why is there a white (neutral) wire? This is because in that same box, there was a single-pole switch to turn on an exhaust fan. Forcibly it has a neutral, so I was able to grab that neutral and use it. The original Chicago 3-way worked because the traverl neutral was twisted into the other neutrals in the box. Important note: no neutral? The Maxxima will not work because it needs power to run itself. What kept me from using the Maxxima in the "dead-end" box is that there was no neutral (hence, "dead end").

Controls to the Maxxima

As shown, from left to right, top to bottom:

1. Time-delay dial, how long to leave the controlled light or fan running. Turn left to shorten, right to lengthen. Settings are
   • TEST (instantaneous)
   • 1 minute
   • 5 minutes
   • 15 minutes
   • 30 minutes
2. Sensor sensitivity. Settings are 1-5 with no explanation as to which is most sensitive (before turning on light) or least sensitive.
3. Ambiant light level. This controls whether to turn the light on or to ignore motion depending upon the existing level of ambient lighting. Settings are 1-5 with no explanation as to which is most sensitive (before turning on light) or least sensitive.
4. Operation mode button. Settings are
   • Vacant mode (pressed in) disables the motion detection, but retains the timer; if you hit on/off button, light stays on until timer expires.
   • Occupancy mode (popped out—"normal" mode); motion sensoring determines (auto-on, auto-off after timer expiration) whether light is on.
5. Status light that blinks (when sensing movement?) and/or is on in order to show the button when it's dark.
6. On/off button that is really there so the cover can press it.

I purchased the bender head and a handle for working on solar-power electrical improvements (installation of current transformers).

Benfield® Style Hand Bender: How to Bend Guide, 960 Series Benders.