How to find hot side of switch

[WaterlooMarc]

This is probably a stupid question and believe it or not I’ve actually done quite a bit of wiring and managed to not burn anything down or kill myself. Since I’d like to keep it that way I will open myself up to ridicule.

We bought a lake house last fall that has had shall we say quite a bit of creative wiring done to it over the years. Two of the bedrooms have the outlets switched to the main light switch in the room but they never split the outlet - kill the switch kill all the power. (On others I have seen either the top or bottom kept power) Since the outlets aren’t close enough to remedy that without tearing out more wall than I would like I want to install a whole new outlet basically straight down from the switch pulling off the hot supply wire to the switch. So my question is how do I determine which set of wires is which? Is it as simple and putting a multimeter on the screws while the switch is off and see which reads current? Or will I send myself across the room if I do that?

Thanks

Marc

[fixtureman]

Get a non cantact tester

[Snipe Hunter]

Get a non cantact tester

Or a multi meter. Set it to 110v. With the switch off, put one probe on the ground and one on the the black wire (usually black on the brass screw... usually). If that ain't hot, it's the other wire.

[blackhat]

I would strongly recommend that you do not attempt to determine the hot side by measuring current. You could end up across the room or at least blow up your meter. Voltage measurements would be safer and more useful. 

All that said, if you suspect the wiring of existing circuits, why not pull a new, correctly wired circuit where you want?

[shifty]

How many wires are in the switch box? Is it possible the wire feeding the outlets comes into the switch box? If so, just move that wire from the switched hot to the supply hot. Then your outlets would be hot all the time.

[MstrCarpenter]

The previous three replies are all good advice. You said "set of wires". So there are only two cables in the box, both with a black, white and ground? If so, I assume the two whites are connected together with a wire nut and the two blacks are on the switch. If there's a black and white attached to the switch, something else was planned or changed. Did you look in the receptical box to see how they're wired? Is there a ceiling lamp controlled with the same switch? Is there a red wire anywhere? Lots of possibilities in addition to what I assumed. It could be that someone replaced the original outlet and didn't notice the tab conecting the upper and lower half of the duplex receptical removed; "Two whites on silver screws and two blacks on brass. I just watched it on a Youtube video. Simple. Right?"

[lincmercguy]

"Get a non cantact tester"

I think everyone who even changes a switch or outlet should have one of these. They are cheap. It's also a good, quick way to make sure a breaker is off before you do anything.

[crokett™]

If the switch only has one cable coming into the box (1 black, 1 white, 1 copper wire) then power doesn't come into the switch, it comes into box at the light fixture. If this is the case the black and white wires from this cable will both be connected to the switch. This is not common and might even be against the rules now, but I have seen it before.

[MstrCarpenter]

If the switch only has one cable coming into the box (1 black, 1 white, 1 copper wire) then power doesn't come into the switch, it comes into box at the light fixture.    If this is the case the black and white wires from this cable will both be connected to the switch.  This is not common and might even be against the rules now, but I have seen it before.

The circuit is still used (Switching half of a duplex receptacle is a perfect example.)  but now a neutral is required to be in the box. Even though it's not needed for a simple single pole switch, some occupancy and vacancy switches need a neutral and using the ground as one is frowned upon.

[crokett™]

The circuit is still used (Switching half of a duplex receptacle is a perfect example.)  but now a neutral is required to be in the box. Even though it's not needed for a simple single pole switch, some occupancy and vacancy switches need a neutral and using the ground as one is frowned upon.

I'm not sure what you are trying to articulate.  If there is only one cable coming into the switch box, he can't do what he wants to do, at least not legally.