# Electrical question



## MrRon (Jul 9, 2009)

This is a woodworking forum and I know there are some electricians on this site, so I have a question for you. I am extending a circuit from an interior receptacle, going through the wall to the weather and terminating in a switch which will in turn provide a path to outdoor receptacles. Obviously all wiring devices will be in weatherproof boxes and wiring will be in conduit. My question then is; do I need a DPST switch (switch both legs) or can I use a SPST switch in the outdoor? I could probably get by with a SPST switch, but I don't want to be in violation of the NEC. If I need the former, where can I find such a device? I know they are available as a toggle switch, but is there one with the wall switch configuration?


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## Gilley23 (May 9, 2017)

Just wondering, but why are you switching the outside receptacles, for plugged in lighting?

Either way, only a SPST switch, you only need to switch the hot. The neutral will remain unswitched.


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## MrUnix (May 18, 2012)

I'd use DPST so both legs are switched, particularly when extending an existing circuit that may have something plugged into it upstream (thus making the neutral hot as well). Only slightly more expensive, but safer IMO. Got no idea what the code sez about it, but I'm sure one of the code gurus will chime in shortly.

Cheers,
Brad


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## MrRon (Jul 9, 2009)

> Just wondering, but why are you switching the outside receptacles, for plugged in lighting?
> 
> Either way, only a SPST switch, you only need to switch the hot. The neutral will remain unswitched.
> 
> - Gilley23


I want to completely isolate all wiring in the weather from the house. The outdoor receptacles would be used for lighting, radio, coffee pot, etc.


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## Gilley23 (May 9, 2017)

You can use a DPST switch if you'd like, but it's not necessary. Simultaneously switching the hot and neutral in this situation functionally does nothing. When you switch the hot off, the neutral is dead wire.

Personally if I wanted to switch everything, I'd put the switch inside and only have the receptacles outside. Put a gfci in the first receptacle, load side the rest off of that gfci and call it a day.


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## patcollins (Jul 22, 2010)

> You can use a DPST switch if you d like, but it s not necessary. Simultaneously switching the hot and neutral in this situation functionally does nothing. When you switch the hot off, the neutral is dead wire.
> 
> Personally if I wanted to switch everything, I d put the switch inside and only have the receptacles outside. Put a gfci in the first receptacle, load side the rest off of that gfci and call it a day.
> 
> - Gilley23


A lot of people don't realize that plugging something into that circuit upstream will complete it because it has electricity flowing through it on to the ground. If you put a screwdriver on a neutral and have a path to ground electricity will flow through you from the neutral. The electrons don't stop flowing at the device.


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## JADobson (Aug 14, 2012)

Electrical questions on a woodworking forum! Geez you can't help but stir up trouble can you?  jk


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## WhyMe (Feb 15, 2014)

I'll just add if you are not aware, the outlets outside also need to be weather resistant (WR) on top of needing to be GFIC protected and have weatherproof covers.


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## Gilley23 (May 9, 2017)

Ok stop. Seriously?



> A lot of people don t realize that plugging something into that circuit upstream will complete it because it has electricity flowing through it on to the ground. If you put a screwdriver on a neutral and have a path to ground electricity will flow through you from the neutral. The electrons don t stop flowing at the device.
> 
> - patcollins


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## MrUnix (May 18, 2012)

> Ok stop. Seriously?
> - Gilley23


Yes… Seriously.

Cheers,
Brad


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## patcollins (Jul 22, 2010)

> Ok stop. Seriously?
> 
> A lot of people don t realize that plugging something into that circuit upstream will complete it because it has electricity flowing through it on to the ground. If you put a screwdriver on a neutral and have a path to ground electricity will flow through you from the neutral. The electrons don t stop flowing at the device.
> 
> ...


My dad found that out the hard way, welding a screwdriver to the electrical box, shocking himself, and dropping a $200 brass light fixture on the tile floor.


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## Fresch (Feb 21, 2013)

Then the wiring was wrong or your dad did not know what he was doing.


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## alittleoff (Nov 27, 2014)

Out of the electrical business for quite awhile now, retired but I believe it against the N.E.C to switch the neutral conductor. It may have changed since I quit working, but its really no reason to switch it anyway. 
Gerald


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## patcollins (Jul 22, 2010)

> Then the wiring was wrong or your dad did not know what he was doing.
> 
> - Fresch


The current flows from the hot side, through the motor, light bulb etc, through the neutral back to the source. Providing a path to ground from the neutral provides a way for electricity to get to ground, which is where it wants to go.

Where do you think the current goes to after it flows through the device?


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## patcollins (Jul 22, 2010)

Here is a pretty good link about why you can get shocked from the neutral wire. Long story short is there is always potential between one ground and another, generally it will be less than the full 120 volts though.

http://ask-the-electrician.com/the-shocking-truth-about-neutral-wires/


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## Gilley23 (May 9, 2017)

Patcollins, I fully understand why you're saying what you're saying, but that would not at all be the case with this setup.

The only time you can switch a neutral wire is if you simultaneously switch the hot wire along with it.

MrRon, if you truly have the desire to install a switch, just do a SPST and be done with it.

I'm done on this thread, it's in your hands now!!!


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## ArtMann (Mar 1, 2016)

I hate to be blunt but you really need to leave the electrical advice to people who have some idea of what they are talking about.



> I d use DPST so both legs are switched, particularly when extending an existing circuit that may have something plugged into it upstream (thus making the neutral hot as well). Only slightly more expensive, but safer IMO. Got no idea what the code sez about it, but I m sure one of the code gurus will chime in shortly.
> 
> Cheers,
> Brad
> ...


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## Fresch (Feb 21, 2013)

Ok, the black wire is connected to the breaker, then to a switch, then to the black wire of the light fixture, the white wire returns to the breaker box lands on the neutral buss, neutral buss is bonded to the ground and breaker box.
Close the light switch, light turns on, open light switch light turns off, how did you get electricity with an open circuit?
Your link talks about an open neutral completely different problem. 
As I said incorrectly wired.
Do you know the correct wiring configuration for a 120 volt light socket, or receptacle?
Do you know how to wire a spst switch into a circuit?


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## patcollins (Jul 22, 2010)

> Ok, the black wire is connected to the breaker, then to a switch, then to the black wire of the light fixture, the white wire returns to the breaker box lands on the neutral buss, neutral buss is bonded to the ground and breaker box.
> Close the light switch, light turns on, open light switch light turns off, how did you get electricity with an open circuit?
> Your link talks about an open neutral completely different problem.
> As I said incorrectly wired.
> ...


If a single light bulb is the only thing you have on that circuit then that is the case. But if there is anything else on that circuit then you can provide a parallel path to ground via the neutral wire. The amount of current that will flow through each path to ground will be proportional to the resistance in each path to ground (voltage divider basically). The ground doesn't necessarily have to be bad to get flow through an alternative ground as the potential at two discrete points is never the same.

Lets say there is a total current of 10 amps flowing through the circuit, the ground through your body has a resistance 10x that of that resistance through the neutral line. The neutral line will take 90% of the current to ground but your body will take the other 10%

If you had long enough meter leads you could most likely measure a potential (voltage) between the neutrals of two different outlets in your house that would not be insignificant.

Yes I do know the correct way to wire a household outlet, it isn't where my experience is so I am a bit foggy on residential and commercial code for buildings. I design electrical systems for aircraft, but the science is the same.


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## MrUnix (May 18, 2012)

> I hate to be blunt but you really need to leave the electrical advice to people who have some idea of what they are talking about.
> - ArtMann


DANGNABIT!!! I knew all that money spent getting an EE degree was a waste!

Perhaps the phrase "making the neutral hot as well" was a bit over the top… but there is still an electrical potential on the neutral if something is plugged in upstream before the switch.

Cheers,
Brad


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## BenDupre (Jan 23, 2017)

Not an electrician but im pretty sure you're not supposed to switch the neutral wire. Dpst switches are for 220 V circuits with 2 hot legs.


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## MrRon (Jul 9, 2009)

This may help explain what I am trying to accomplish. The upper diagram shows the DPST switch and the lower diagram shows the SPST switch. The ground wiring is not shown.


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## SignWave (Feb 2, 2010)

I don't think that this has been mentioned yet, but GFCI's switch both the neutral and the hot wires, so they are essentially DPST during a fault. [This is a useful thing to know if you're troubleshooting a dead outlet and you suspect it may be downstream (i.e. on the "load" side) of a GFCI.]

I am not going to tell you what to do, but you might want to consider this in your planning.


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## patcollins (Jul 22, 2010)

> Not an electrician but im pretty sure you re not supposed to switch the neutral wire. Dpst switches are for 220 V circuits with 2 hot legs.
> 
> - BenDupre


The double pole switch would be for the purpose of completely isolating the outlet outside, for whatever the reason the original poster feels the need to do so for, it would be the same as putting a wire out there that was not connected to anything.

I was pointing out that it is possible to have a flow of electricity with a single pole switch on the hot side turned off.

Probably total overkill in doing so, I found a live wire broken off in the ground outside from a pond pump electrical run done very poorly by the previous owners of my house that a stump grinder cut in half at some point.


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## clin (Sep 3, 2015)

Chiming in on this hot-neutral idea. As pointed out, the neutral is only going to go to high voltage, IF (real BIG IF) it is disconnected somewhere and therefore isn't connected to ground back at the panel. This of course is a wiring fault.

This is a reason you shouldn't work on live circuits. Though obviously sometimes you must in order to locate the fault. But always best to treat both hot and neutral as hot. If for no other reason, do you really trust that some knucklehead didn't swap a white and black wire somewhere in the circuit. Especially a circuit that's not working right.

And yes, current flows in a properly connected neutral, and yes, if you connected something between that neutral and ground, some current will flow through that to ground. For a normally wired neutral, this would not be dangerous.

Take a #12 wire (1.6 mOhms per foot) say a 100 ft run of wire, that's 0.16 ohms of resistance. Run 20 amps through that to develop 3.2 V at the far end of this wire. 3.2 V of course is not dangerous. But sure, if you put a 1 ohm resistance from this point to panel ground, you'd get 3.2 A flowing through that resistance (actually a little less). If you shorted this out with a screw driver, you might even get a small spark. But not the big burn the tip of the screw drive spark you'd get from shorting the hot.

And of course, if you get current flowing from the neutral to ground, the GFI will trip. That's the while point of a GFI. If all the current in the hot isn't coming back through the neutral, it's going some other place it's not supposed to, and that is likely a shock or fire hazard.

The thing about the OP's idea that concerns me is chaining multiple sockets/loads off an existing socket. Code limits the numbers of sockets on a circuit. This sounds like it has the possibility to exceed that.


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## MrRon (Jul 9, 2009)

I am trying to extend the circuit from the closest interior receptacle that is located in an exterior wall. I think I will go with a single pole waterproof wiring device and a GFI. Thank you all.


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## bandit571 (Jan 20, 2011)

Sounds like a Plan….


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## rbrjr1 (Nov 2, 2017)

lol.

DPST switches are for 240v
SPST switches are for 120v

There is absolutely NO reason to use a DPST switch on a 120v circuit and depending on the existing wiring, you can adversely effect the other devices on the existing circuit.


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