House wiring question

[ps2cho]

So I installed a timer in place of the on/off switch in the wall for my outside light.

After I finished (and it works) I realized that I have my GND wire accidently in the neural white wire coming out of the timer.

The stock switch had GND and 2x black wires.
So I hooked up:
Out of wall --- new switch
GND to white
Black to black (line)
Black to blue (load)

The timer works...but is this a fire hazard or anything since I didn't read the manual correctly?

[oldsinner111]

I would rewire it,but know fire risk.

[barry12345]

Safe but out of code. It works of course because the neutral or white wire terminates at the panel at the same electrical potential as the ground wire does you are using.

There are rare cases where I have had to run an additional neutral to stay in code.

[link]

Rewire to follow code.

Weird and potentially disastrous results can happen down the line when code is not followed consistently.

[TwitchKitty]

Rewire to avoid scorn, ridicule, derision. Insurance rules in such matters.

[cmac2012]

There is generally not a neutral wire in a switch box. There are two ways the box in a switch can be wired. It depends on whether the live current plus neutral wire plus ground - the standard three wire Romex - first goes to the light fixture, or whatever the load is, or to the switchbox. Both are employed and both are legal. When it goes to the fixture, a two wire line goes to the switchbox. Often it is a Romex with ground that is used for that, in such cases the ground wire is not really needed for anything. The black and white wires in such a case may as well be both black, as neither will ever be a neutral wire. The way we electrician types think of it is: you hook the white wire going to the switch to the hot wire, the black wire in the light fixture, and in the switchbox you hook the white and black to the two terminals on the switch. This is assuming it's a regular old switch with no need for any current doing anything internally. More on that later.

When the switch is turned on, we call it turning white into black, and the black wire is then taking live current back to the fixture box where is connected to the black load line on the fixture. The white neutral line coming into the light fixture box is hooked to the white load line on the fixture, it never goes anywhere near the switchbox. When all is said and done, it's as if you have a switch right at the light fixture box and it interrupts the black, live line just before he reaches the fixture.

In the other method, the live three wire Romex goes to the switchbox and a two wire line plus ground - a standard Romex bundle - is sent to the fixture. The white neutrals are wired together. The black going to the fixture is on one side of the switch, the live black coming to the switchbox is on the other side of the switch. The green or bares are wired together and you ground the light fixture with it.

The applications where this can become difficult is where you have a switch, such as some timers, that require a little bit of current to make the switch work. Your situation is maybe working because the ground going away from the switchbox was hooked to the ground at the fixture, something that is really not necessary and is often not done. Certainly not in the old-style wiring, more and more it is done in the new. A lot of the safety on this would depend on whether or not the ground wire coming into the switchbox originally was the green insulated type or the bare type. Doesn't really affect fire hazard much, it might mean one would get a mild shock handling the light fixture at some point. Current going through bare wire is not usually a fire hazard by itself. If the line gets so hot that it will start a fire, it will be happy to use the plastic insulation as kindling for the fire.

It can sometimes be a real headache getting a neutral line into a switch box like this when you need it. I have gone to great lengths to do so at times.

I tend to get cavalier about the need for a groundline as so often I'm wiring into existing older wiring in old houses that don't have a groundline. Putting one in place can be very labor-intensive and it's often not needed. A groundline is a good idea with hand power tools because if any short develops where current would be going into the handpiece, it is instead ran off through the ground line rather than through your body. My guess is a groundline in a light fixture actually accomplishes anything in one out of a million applications. But I don't think the law sees it that way.

[cmac2012]

In short, those who say 'rewire' here are leaving out the fact that to do so would require running a neutral white line up to the switchbox. This can sometimes be halfway easy, you can grab a white neutral line from an outlet box, and if one of those happens to be in the same stud bay you can do that with some finessing without doing any sheet rock work.

Another way is to find a neutral line either in the crawlspace or attic and somehow fish it into the stud be where the switch is and get it down into the switchbox. If it's a wall with insulation in it, whoa, can be a serious chore, as in nearly impossible.

*EDIT*

Upon rereading the remarks of others I see that they do clearly get that a neutral wire would need to be run to the box to rewire correctly. I wasn't sure if you understood that or not, you being the OP.

I was primarily a carpenter for a long time before I really learned about wiring. There are a few things I still don't know surprisingly enough.

There is one possible way to rewire it that would be a lot less work and still be pretty safe. If the ground wire is the green insulated sort, go to the light fixture and find the line coming from the timer to the fixture and wire that ground wire into the white. It would even work if it's a bare wire but most people are going to be squeamish about that. I think it would be okay because the timer is going to draw a very tiny amount of power. Therefore the current in that line will be next to nothing.

But if you leave it as it is that tiny amount of current would be going through all of the ground lines that are hooked up upstream or downstream from that light and that might cause a small perceptible shock somewhere as the ground line is often hooked to exterior structures.