How can I combine two outlets into one output using OR logic?

Question

I need some sort of electrical device which would combine the output of a switched electrical outlet with a programmable timer plugged into a non-switched outlet. Then I would plug lamps into said electrical device, and have the timer set to be on only from 10 minutes before my alarm goes off in the morning, to 10 minutes before I need to leave for work. This way I could turn my lamps off at night, the timer would turn them on in the morning, then turn them off right before I leave for work, and then when I come back, I can use the wall switch to turn them off and on as I please.

I'm pretty sure this cannot be done and would most likely short out, but the way I visualize this is something like an extension cord with two outlets, and then put Male to Male adapters on the outputs and a Female to Female adapter on the input.

From what I've read, it seems what I'm looking for is very similar to a redundant power strip, however these are $150+ and I'm looking for $25 and under. I'm guessing there would also need to be some sort of relay to switch which power source is being used to power the power strip, and to prevent any shorts.

        Switched Outlet ->  ||
                            ||  -> Lamps
Normal Outlet -> Timer  ->  ||
                            ^
                            | 
                  Mystery Electrical Component

Answer 1

It sounds like a light switch with a built-in programmable timer would meet your needs.

Here is an example of one that turns on at preset times for under $25: http://www.amazon.com/gp/aw/d/B004SOZHXY/ref=mp_s_a_1_1?qid=1435319450&sr=8-1&pi=AC_SY200_QL40&keywords=timer+switch&dpPl=1&dpID=31IbSTB9PVL&ref=plSrch.

I have a similar switch where the timer is slightly fancier in that it turns my porch light on and off relative to the known times of sunrise and sunset throughout the year, but otherwise it's the same thing. I have been happy with my switch/timer's performance.

Answer 2

There probably isn't anything you can buy that does this for a residential application, but it's done all the time in industrial plants, like this:

As the drawing suggests, make good and sure that you're only using ONE phase. In other words, don't put the switch on one phase and the timer on the other, wire them together, and expect them to work.

Call an industrial electrician if you're not sure about doing this yourself; I wouldn't expect a residential one to understand this. (When I worked for an industrial controls company, some customers hired residential guys to do the wiring. I was very impressed with them...the wrong way.)

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Alternatively, most residential timers have provisions for manual override, as long as you can access the timer itself. But judging by your question, it seems that you want to bury the timer and forget about it.

Answer 3

The scope of such a project is actually possible for under $35-$50 but would require some knowledge on embedded operating systems and some circuit input/output, plus python computer programming skills.

The project starts with what is called Raspberry PI and from there the fun begins.

Raspberry PI Tutorial

Other alternatives are available, some obsolete but free plus these obsolete options may have less up-to-date support e.g., Linux and X10 software since X10 has fallen defunct in the past 10 years.

Proprietary software APIs such as Insteon are also available too, but I'm not a huge fan of Insteon.

Personally I use Linux and a free software called heyu

I use crontab to automate functions with my X10 devices.

Answer 4

From the hardware store, get a hard-wired timer, two appliance cords (or one long appliance cord or an extension cord), an outlet, a switch, a box and cover for the outlet, a box and cover for the switch, and 4 wire clamps that fit the knockouts on the boxes. You'll also need a bit of spare 14 or 12 gauge electrical wire and some wire nuts.

1. Figure out how to align the box for the outlet to the timer box so that one knockout on each aligns. Open those knockouts and attach the boxes together using one of the wire clamps.
2. If you bought 2 appliance cords, cut the plug off one of them and strip the wires. If you bought 1 long appliance cord, cut it in half or so and strip the ends.
3. Open two more knockouts on the timer box. One will be for the appliance cord with the plug to power everything, and the other will be to connect your frankentimer to the switch box.
4. Connect the appliance cord to the timer box using the wire clamp. Connect the neutral and live wires to the neutral and live/line terminals of the timer.
5. Using the spare electrical wire, install and connect the outlet in to the outlet box. Connect the neutral on the outlet to the neutral on the timer and the live on the outlet to the load terminal on the timer.
6. Attach the appliance cord without the plug with a wire clamp to the frankentimer. Connect the live wire to the live/line on the timer, and the neutral wire to the live on the outlet. Also, wrap a little electrical tape "flag" around the neutral wire at both ends. This will signify that this neutral wire is actually live when the switch is on.
7. Connect the other end of the appliance cord to the box for the switch. Wire in the switch and close up the box.
8. Connect all of the ground wires together with a wirenut. You should also ground the timer according to the directions, which will probably require you to use a small "pigtail" piece of spare wire to connect the wirenut to the ground screw on the timer.
9. Close up the outlet box.
10. Install the wiring cover in the timer box, if your timer came with one.

Note: Consult the directions that come with the timer. The terminals may not be rated to hold more than one wire, or wire of different gauges. If that is the case, instead cut a small "pigtail" piece of spare wire to connect to the timer terminal, then wirenut the other wires to the pigtail.

Once all this is done, you can plug in your frankentimer and set the time and timer. Plug your lamp in to the outlet, and place the switch somewhere convenient. The switch will turn the lamp on independently of the timer.