Can an eletrical circuit be powered from 2 cuircuits? I live in the USA.?

Question

A circuit (circuit A) powers my outside lights from a wall switch. I'd like to add a timer to also control these lights, getting power from circuit B to opereate the timer and passing power to the lights, while still being able to use the switch from circuit A to turn these lights on when the timer is not sending power to the lights. Can this be done? What will happen if the circuit A switch is turned on, and the timer is also sending power to these lights? Does it matter where the circuit breakers are located in the fuse box? Currently they would be on different sides of the box.

Answer 1

NO you can't use 2 hot curcits to power 1.  If you were to power both at the same time you could do some serious problems.  Go to your local hardware store and get a timer with on/off

http://www.amazon.com/LST100W-Digital-Sw...

it is a normal on/off switch with the ability to be programmed as a timer as well.

ADDED

Sorry I made a mistake you can use 2 hot if its a 240 circut, but I'm guessing its not in this case.

Answer 2

There is a simple fix to this.No need to over-engineer a simple switching circuit. Buy a timer that has a remote by-pass built into it! There are so many types available it boggles the mind! Go to your local eletcrical supply house and tell them what you are trying to do.They can help you get the correct type of controller. Be ready to answer a few basic questions like, Voltage, number of lights ,wattage of each light,ect.. Most controllers nowadays come with  a couple of wiring diagrams to aid in installation.

Just remember, safety first ! Familiarize yourself with the basic knowledge to do the job.

I wouldn't recommend trying the A-B "selector switch recommended to you. It presents a danger of neutral line back feed. Basically what happens is,if your circuit trips ,you get a reverse flow of power at 2 and 1/2 the line voltage! Or more simply stated ,you trip a breaker and suddenly instead of 110v ,you have 275v !  I argued this point with my professor ,he demonstrated it with my radio.I've never seen that much smoke before!

Answer 3

DO NOT try to mix two separate circuits that way.

it is against the Code, and unsafe at best.

If circuit B is on a different phase from A closing both

switches would create a 240V. short circuit.

If you got the phases right, the wire would be unprotected. (Double the rated amp.s available.)

You can install the switch to bypass the timer,

(or vice versa), on the same circuit.

It will accomplish the same result, but a whole lot easier and safer.

Answer 4

No No NO!

You can't power one fixture from two circuits.  Never.  Forget code (although it does not allow for it) this could create a dangerous situation.

This warrants a bit of explaination.  Suppose circuit A is attached to 1 leg of your service panel, circuit B is attached to the other. (BTW, with modern panels you can't assume that a breaker on a particular side of the panel is attached to a particular leg - the newer busses sometimes cross sides).  If the timer (on circuit B) is on, 120 volts will flow to the fixture, and since the switch is connected to the same fixture that same 120 volts will flow to the switched leg of the switch.  There is 120 volts connected to the feed leg of the switch in the opposite phase.  If (when) the switch is turned on, the two circuits will be connected creating a 240 volt short.  One or both breakers should trip, if not something else will.

The correct way to create what you are trying to do involves the unconventional use of a 3-way switch.  I should point out that you should have a basic knowlege of electrical circuits before attempting this.  I though a bit about providing this, but even experienced electricians may not have seen this particular circuit before, so if you don't understand hand it over to your electrician.

Timer line side is connected to a circuit.  The hot wire from the switched side of the timer is connected to leg 1 on the 3-way switch (note I mentioned unconventional).  Now connect leg 2 of the 3-way to the SAME circuit at a point before the timer.  The common leg of the 3-way is now the switched leg and should be connected to the fixture.  The 3-way switch is now a "selector" switch.  In one position, the timer controls the circuit, in the other the circuit is switched on directly.

Answer 5

no, if you power 1 circuit with two hot wires you will have a dead short causing your breaker to trip or maybe burning your house down, the only time two hot wires are needed is on a 240v circuit.

Answer 6

This can be done, but trying to explain it here is way too difficult.  You need to hire an electrician.

Answer 7

I just found a similar thing in the house I recently bought. I had to call an electrician in on an emergency basis to rewire my dishwasher after the plumber found that it was wired into not one, not two, but THREE circuits. Had it caused a fire, my lawyer said that my insurance company could have gone after the vendors for hundreds of thousands of dollars - and that's not counting any suit for wrongful death or injury from me or my estate.

Electricity is not something you want to cheap out on. If you don't know exactly what to do, call a pro and get it done right and within code. It's worth it, not just now but in the long run: you don't need a lawsuit in ten years' time.