Need some electrical advice.

[Frunple]

Okay, here's what I have:
A 20A 12/3 going out to my front yard with the Black feeding 2 outlets and the red feeding 2 lights on my flag pole. So obviously the outlets are constant hot from the 20A breaker. The lights I want to control from an existing switch.
The existing switch is at my front door and was never connected to anything when they built the house (don't ask me why, must've had something in mind and then they changed it) but it is extended to the basement on a 14/3 red wire. All neutrals and grounds are bonded between lights and outlets.

Now what I want is to use the switch to control the lights, using the existing 15A hot that's already in the box at the front door. So how would I connect the 2??

Should I just run a 12/2 from the red of #14 from the switch and bond all neutrals and grounds together, or leave the neutral and ground disconnected???
Not sure with this. Seems like the switch (being a 15A) would be fine since it would be fed from a 15A breaker and only controlling well under 15A lights, but the neutrals got me stumped. Is it ok to bond 2 circuits together since they are different amperage?
Any help is appreciated.

 

[pete_c]

I would separate to two circuits; one being the switch and the 15 AMP for the lights connected / disconnected from the old hot lead new and keep the 20 AMP circuit just for the two outlets. For different circuits I usually use separate neutrals (white here) with separate autonomous runs to the fuse panel. But it looks like you don't really have a choice but to share the neutrals (white) between the two circuits. You could also just remove the hot from the switch and use the hot from the already running outside lights and keep it to one circuit.

Here in the midwest I have a kind of similiar set up with 14/3 underground cable going to the mailbox. One run is switched for the mailbox (build a brick and glass block thing and the lighting is inside of the brick mailbox). On the brick structure is one outdoor outlet. I used to have the switch in the basement for the mailbox. I then ran more wires up to a 4X4 box in the front foyer and added a switch / UPB now for the mailbox lighting. (it is only three wires on one 20 amp circuit )

OLD -
20 AMP circuit going to three 12/3 wires
- Red - Hot to Lights
- Black - Hot to outlets
- White - neutral

Switch (15 AMP) wired with 14/3 wires but only going to the basement. Are these run to the fuse panel also? Is the circuit 15 AMPs or are you referring to the switch as a 15AMP switch?

NEW - suggested:

- one circuit; 15 AMP swapping out the 20 AMP breaker for a 15 AMP breaker

#1 new breaker in panel replacing 20 AMP with 15 AMP on 12/3 run.
Use two wires - black (hot) and white (neutral)
#2 15 AMP circuit/wires from switch - disconnect in basement.
Use one wire - black to red wire going to switch and
share white neutral between the two runs (outside outlets and two flagpole lights).

BTW I utilize GFI's for all outside outlets (you already know that though).

 

[Frunple]

The problem with your advice is then I'd be using #14 wire on a 20A circuit, not good.

Anyone else?

 

[tmbrown97]

Well on this particular forum, I'm sure someone will suggest using UPB - at the pole add an inline dimmer or relay module, and at the switch location, put in a UPB switch with no load attached just to send the on/off commands. Doesn't have to be UPB - could be any of the lighting technologies.

Are you 100% sure about that switch and where it goes? I could be as simple as being one outlet in a two-outlet box going anywhere in your house, or some capped load or something else. Pretty strange to have wires go nowhere (are they capped or what?).

For the outside outlets, if you share a neutral and they're on a GFCI, you'll trip the GFCI if the load on the neutral doesn't match the load on the hot. If it's a GFCI breaker it definitely won't work; if it's a GFCI outlet and it's in the right place in the circuit, it may not trip...

regardless... I'm not an electrician, but I did a bit of reading on shared neutrals when a good friend had all the appliances in her kitchen blow up... basically it was the one legal way you can have a shared neutral, but a wire nut came loose where several neutrals were supposed to tie together - esentially causing the neutral to turn into a hot and basically feed 240 volts (or somewhere in between - there's a whole lot of details to this) to all her appliances; fried her fridge, stove (gas stove so 120v for the controls), microwave, etc...

If I remember correctly, the only way you can share a neutral is if both hot loads are on opposite phases, and both circuit breakers are bonded together the same way as a 240v breaker so they're both on or both off together.

Continuing my thought process a little bit, I suppose if you did this to code for split breaker, you could downgrade the breaker for your outlets to a 15Amp, make sure you have the clip connecting the two breakers (may have to rearrange a little), then figure out where to tap your existing switch's hot into the the wire that currently feeds the light... done right, that'd be legal... unless having #12 connected to #14 is against code.

 

[gatchel]

I believe that MWBC's (Multi Wire Branch Circuits) are also required to have all box connections pigtailed so that the neutrals and hots have a mechanical connection other than the outlets screw terminals. If the outlet fails, you don't run into issues mentioned above.

Also, IMHO, mixing 14 and 12 guage wire on the same circuit is a bad idea regardless of what code says even if you feed it with a 15 amp breaker.
You may know what's going on but if you sell and the next person isn't so smart...you get it.

 

[video321]

To get away with what you're trying to do (never mind how to make it work) would be to replace the 20A breaker and receptacles with 15A. That is the only way you can get 14ga. wire on that circuit. Once you do that you can wire in that switch and the 12ga. wire becomes "an added bonus" on that circuit.

...of course, don't just listen to me; check with your local codes.

 

[thadsaab]

As Work2Play mentioned, there are home automation solutions that will work well in this situation.

If you were to make a multi-wire branch circuit, you would need to use a 15 amp double-pole breaker for the two circuits to share a neutral. You'd have some research to do if you were to take that route, it still might not be permitted.

I suggest you consider replacing the 20A breaker with a 15A breaker and wiring the light using a switch loop with the existing 14/3 supplying hot and neutral to the switch on black and white and returning the switched hot on red. There would be no connection to the existing 15A hot. You can have GFCI protection for the whole circuit before the switch loop, or you can have separate GFCI outlets at each location, depending on the details of your installation. This way, it's all on one circuit. But, the breaker must be reduced to 15A because of the 14 gauge wire. You should seriously consider gatchel's comments about future owners. If there is a way for you to replace the 14/3 with 12/3, that would be best because you could keep the 20A breaker. Alternatively, using 14/2 to the panel and the 12/3 only outside with the 15A breaker might be sufficiently clear to prevent anyone from getting the wrong idea.

What else is on the existing 15A circuit by the front door? Why not use that for all of the outdoor outlets and lights?

If you need 20A for the outdoor outlets, you probably have to replace the 14/3 to the front door with 12/3 and use the method I described above, or use some home automation (X10, UPB, Z-Wave, Insteon, etc.).

 

[sic0048]

There is no way you are using even 15amps on the circuit, so I too would recommend swapping the existing 20amp breaker for a 15 amp breaker. Finding the right breaker is the hard part (because there are so many different options and you need to find the right one for your panel), but actually changing the breaker out is very easy.

 

[pete_c]

Same here about downgrading the breaker. Easy to do. Just be careful. Snaps right out. Take it with you to the hardware store.

 

[Sandpiper]

There are several ways to approach this, but whichever way you go, make sure you do these:

1. Do not connect the neutral (white wire) of different circuits together. (except, by definition, a multi-wire branch circuit (2 pole breaker) shares a neutral between the black and red feeds).
2. Do not use #14 AWG wire in a 20A circuit. 15A is OK.
3. Make sure the outdoor outlet circuit is fed from a GFCI, either at the outlet or at the breaker.
4. Do connect the bare grounds together (bond them).

 

[Frunple]

Right now I am using a UPB inline relay to control the flag light. What I want to do is use a UPB switch so the wiring would be in place since I may be moving in a few months, just trying to be able to remove all UPB and replace with regular switches.

I can't change the 20A to a 15A, it has my central vac and other things... needs 20A.

The existing 15A circuit is just lights so I may try to add the outside stuff onto that breaker as Thadsaab suggested... this is the way to go if I can get a constant hot for the outlets from it, not sure if I can without ripping off some sheetrock.

Thanks for the suggestions.

 

[apostolakisl]

If all of this is powered by the 20amp breaker, then there is no way to use the 14g wires going to that switch. You can not have 14g wire getting power from a 20amp breaker regardless of the actual draw. Furthermore, even if you could add another 15 amp breaker and power the 14g with it, you can't use the 12/3 wires because that would require putting the two hot leads on two different breakers (since you said it also powers your high amp central vac). The only code way to put them on 2 different breakers is to use a 220 breaker and then both legs would have to be 20 amps and be tied together. You can't have 2 wires in the same jacket on separately controllable breakers.

Perhaps you could use a 15amp supply to the switch at the front door. Turning on the switch would power a 120v relay in the basement. When on, the relay closes your 20amp supply to the red wire on the 12/3 turning the lights on. I think that could be done to code but not 100% sure. This requires that all these wires are comming together in the basement along with your breaker panel.

Otherwise, pull new wire from the switch at the front door that are 12g.

 

[Frunple]

Lou, I don't think you got the gist of what was going on. Your first paragraph of saying what I can't do is exactly what I was saying I can't do in the original post. Also, pulling #12 to the front door would accomplish nothing since that's the 15A breaker. the 20A breaker comes from somewhere else.
Anyway, it turns out the 14/3 going up to the switch was actually the feed so I had a constant hot right there in the basement where the #14 red from the switch was. So the black fed the front door switches, and I switched the red going back down, then I just ran a 14/3 from that point to the 12/3 going outside and now the outside outlets and lights are on a 15A breaker and all is well.
Thanks for all the suggestions, I actually never thought of just re-feeding the outside from the door 15A hot but I got lucky with the way it was fed.

 

[pete_c]

Great news there Frunple!

 

[apostolakisl]

Lou, I don't think you got the gist of what was going on. Your first paragraph of saying what I can't do is exactly what I was saying I can't do in the original post. Also, pulling #12 to the front door would accomplish nothing since that's the 15A breaker. the 20A breaker comes from somewhere else.
Anyway, it turns out the 14/3 going up to the switch was actually the feed so I had a constant hot right there in the basement where the #14 red from the switch was. So the black fed the front door switches, and I switched the red going back down, then I just ran a 14/3 from that point to the 12/3 going outside and now the outside outlets and lights are on a 15A breaker and all is well.
Thanks for all the suggestions, I actually never thought of just re-feeding the outside from the door 15A hot but I got lucky with the way it was fed.

Didn't you say you had a 12/3 going out to the yard that fed the lights on one hot and the outlets on the other hot? If so, I don't understand how you are using a 15amp breaker for the lights and a 20amp breaker for the outlets. That would be 2 different breakers on the two hots in the 12/3 that aren't tie together.