Single pole switches are used when only one switch is needed to control one or more lights.
They are the only switch labeled “ON” and “OFF” and the only switch with two terminal screws (with a third green ground screw).
They are identified on blueprints as S1.
Description Power (a hot and a neutral) is fed to the switch with 1 switch leg run from the switch to 1 light. A 2 wire feed is pulled from the nearest source of power like a receptacle or the panel to the switch. 2 wire meaning; either 14/2 with ground (wg) for 15 amp circuits or 12/2wg for 20 amp circuits. A 2 wire switch leg is pulled from the switch to the nearest light.Below is a line diagram and a wiring schematic of a basic single pole switch wiring circuit.
Line diagrams help electricians figure out how to make wiring connections by simplifying the circuit. They are drawn with the hot on the left and the neutral on the right.
Wiring schematics are more like a drawing of the real thing, like a road map.
The hot and neutral are shown in the real world locations that they would be at.
To keep the illustrations simple, the grounds are not shown.
A photo, diagram and schematic of a basic single pole switch circuit with one light.
Basic single pole switch circuit with one light. The cord plug at L1 (hot) and N (neutral) represents power feeding this circuit. You could plug it into a hot outlet and this switch and light would work.
Footnote; * In AC (alternating current) circuits, the flow of electricity “alternates” back and forth from the Line (the hot) to the Load (the light) and then reversing direction from the Load to the Line. When electricians talk about AC current moving through a circuit they speak as though the current is DC (direct current) flowing in one direction from Line to Load. The descriptions in these articles are also written as though the current is DC even though it is really AC current. Think of it as electrical current that is frozen in a split second moment in time moving from Line to Load. In the next split second the current will reverse direction and flow backwards from Load to Line, from the light to L1.
Electrical current begins at L1. This current is coming from the electrical panel or a nearby receptacle. From L1, the current flows through the black wire to terminal #1 on the single pole switch.
through the switch
The switch is shown in the open or off position. Inside the switch, after the switch blade is closed, the current flows through the (purple) switch blade from terminal screw #1 to terminal screw #2.
to the light
It then leaves #2 and follows the next black wire called the “switch leg” to terminal screw #3 on the light fixture. The switch leg wire is only hot when the switch is on (closed). From terminal #3 current flows to a small point on the base of the light bulb where it then enters the bulb, flows through a highly resistant filament wire and then exits the bulb through the base shell which is connected to terminal screw #4 on the light fixture.
and back on the neutral
From terminal #4 current returns through the white neutral wire to the red wire nut connection and back to the neutral.The part that is not shown is how current continues from the neutral to the panel to a transformer coil, through the coil in the transformer from N to L1 where it starts all over again, as explained in the “Introduction to Switch Wiring”
Description Power is fed to the switch and 2 separate switch legs are pulled from the switch to 2 separate lights. A 2 wire (14/2wg or 12/2wg) feed is pulled from the nearest source of power to the switch. The first switch leg is run from the switch to the closest light at the left. A 2nd switch leg is run from the switch to the closest light to the right.
✘ From the hot through the switch, to the light and back on the neutral.
✘ From the hot (L1), through the switch (1,2), to the lights (3,4 and 3,6) and back on neutrals (5,8,N and 7,8,N).
A line diagram and wiring schematic of a basic single pole switch circuit with 2 lights.
Answer; No. The 2nd light can be connected to any point on the switch leg (the switch leg is from 3 to 4 and 5 to 8) The next best connection point would be to connect the 2nd light to the first light (A black wire from 4 to 6 and a white wire from 5 to 7) Splicing into any other point along the switch leg is permitted as long as your connections are contained in anaccessible junction box and the lengths of wire inside the box is 6 inches long. Additional lights can be added as shown below;
A line diagram and wiring schematic of a basic single pole switch circuit with 3 lights.
Why run 2 switch legs to the switch? Answer; If the switch is located between 2 distant lights you will save wire.
Look at the house photo. A switch located by the door at #2 will control 2 lights; one light at #1 and another light at #3.
In the next method power is fed to the light box.
S1 Method #2-1 Light Fed Single Pole
Power (a hot and a neutral) is fed to the light (not the switch) with 1 switch leg run from the light to the switch. A 2 wire (14/2 or 12/2) feed is pulled from the nearest source of power like a receptacle directly to the light box and another 2 wire switch leg is pulled from the light to the switch.
|Numbers in the Line Diagram above correspond to the connections in the wiring schematic and photo below. Electricians use line diagrams to help them figure out complex wiring connections.|
Compare the wiring schematic above with the photo below. Notice that electrical current still flows; ✘ From the hot (L1) through the switch (2,3) to the light (5,6) and back on neutral.(7,N)
|Photo of S1 Wiring Method #2 A light fed single pole switch. http://singlepole.blogspot.com by Jim Morelli|
Electrical current begins at L1 and flows through the black wire to the red wire nut connection #1 in the light box. Current then flows through the white wire that is marked with black tape (not a neutral) to terminal #2 on the single pole switch. Inside the switch, after the switch blade is closed, current flows through the switch blade (purple) from terminal#2 to terminal #3. It then leaves #3 and follows the black “switch leg” wire to the red wire nut connection #4 inside the light box and then on to terminal#5 on the light. From #5 current flows through the filament wire inside the bulb and out to terminal #6. From there current returns through the white neutral wire to red wire nut connection #7 and back to neutral, N.
- Mark the white wire with a black marker or black tape near the ends of the wire
- This white wire with black tape must be used as a hot feed (from #1 to #2) not the switch leg (from #3 to #4).
✓ Unfortunately this method of connecting the hot and neutral inside the light box, instead of inside the switch box, makes it very difficult to access the those connections if any troubleshooting is required. If something is miswired in the light box you might have to go back up a 12 foot ladder and take down a 50 pound chandelier to access the connections in the ceiling light box unaware that one of the wires will still be hot. Beginners will think the wiring in the light box is dead when the light is switched off, but the hot wire that runs from a receptacle directly to the light will still be energized unless the circuit breaker is turned off.
S1 Method #3 Switch Fed, Switched Receptacle
Both the top and bottom outlets on the receptacle are switched on and off by a wall switch.
S1 Method #3.1 Switch Fed, Half Switched Receptacle
Only the top half of the receptacle is switched on and off by a wall switch. The bottom outlet is hot all the time. Power is fed to the switch with a 14/2. A 14/3 is run from the switch to the receptacle using the red wire as a switch leg, the black as an unswitched hot and the white as a neutral. The factory tab that connects the top hot terminal screw with the bottom hot terminal screw is removed. Only the hot tab is removed not the neutral tab. The tab is removed by grabbing it with pliers and bending it back and forth until it breaks loose.
Power is feed to the receptacle with a switch leg run to the switch.
A 2 wire is pulled from a nearby power source like a hot receptacle or the electrical panel, to feed the switched receptacle. Another 2 wire switch leg is pulled from the switched receptacle to the switch. The white wire in the 2 wire switch leg is tagged with black tape and used as a hot.
There is no neutral at the switch and that can be a disadvantage if you need that neutral for something else at the switch box.
The white wire in the 14/2 switch leg is tagged with black tape and used as a hot. The factory tab that connects the top hot terminal screw with the bottom hot terminal screw is removed. Only the hot tab is removed not the neutral tab.
If you want to add a 2nd, new receptacle below this switch and you run a new 14/2 from this switch box to feed the new receptacle below you have a problem; there is no neutral at this switch box. You would have to feed your new receptacle from the first one shown here, even if it is 10 feet away.
A quick note about boxes;
These 3 boxes are called;
➪ At the left is a 4/0 nail on box. Pronounced four-oh. The 4 indicates inches and the 0 represents its round shape. (A 4 inch round nail on box) It is used for lights and smoke detectors The mounting screw holes are for size 8/32 screws.
➪ In the center is a single gang nail on box. It is used for switches, receptacles and smoke detectors. The mounting screw holes are for size 6/32 screws. (Lights are required to be mounted with 8/32 screws not the smaller 6/32 size) The inner volume of all boxes are sized in cubic inches. The standard volume for a single gang box is 18 cubic inch but it is recommended to use a size 20 cu in as a minimum to allow room for large devices like dimmers or GFI receptacles.
➪ At the right is a 2 gang nail on box. The mounting screw holes are also size 6/32
It is used for 2 devices, 2 switches or 1 switch and one receptacle etc.. All device boxes are normally nailed to the side of a stud with the screw mounting holes vertical, at the top and bottom. Rarely are they mounted horizontally with the screw holes left and right.
Don’t confuse this 2 gang nail on box with a 4 inch square box shown below.
You cannot mount switches or outlets to a 4 inch square box with out a device cover
Above is a “4 Inch Square Nail On Box” or “4S Nail On” at the right is a “Single Gang Device Cover” also called a “plaster ring” or “mud ring” The mud ring has to mount to the 4S box to allow switches and outlets to be mounted.
➪ It is better, cheaper and faster to use the 2 gang nail on box instead of the 4S with Device Cover.
(photos by http://www.legrand.us )
Pastel Abstract Switch Plate Covers by ShabzDesigns
View Pastel color Light Switch Cover online at zazzle
Question; What size screws are used to mount a switch to a switch box?
OK back to wiring;
S1 Method #4-1 Combo Switches
Here is what a combo switch looks like;
(Photos by http://www.lowes.com)
Rating Excellent A 🙂
This method is commonly used when 2 switches need to be in a single gang location.
Description Power is fed to the combo switch by pulling a 2 wire feed from the nearest source of power. Then 2 switch legs are pulled from the switch to a ceiling fan. A 3 wire has 2 switch legs in it; a red for the light and a black for the fan with the white being used as the neutral. If you have no 3 wire available you could pull two 2 wires which would leave you with an extra white neutral. One black for the light the other black for the fan and one of the whites for the neutral.
A line diagram and wiring schematic of a combination switch with a light and a fan.
S1 Method #5-1 Multiple Single Poles For One Fan
Rating Excellent A+ 🙂
A rare method used to control a single exhaust fan from 2 or more different bathrooms. The exhaust fan is located in a central location, like an attic, and connected to duct work that comes from all (lets say) 3 bathrooms. Each bathroom has a single pole switch that can turn the fan on or off but the fan can only be turned off at the place where it is turned on.
Description Power is fed to a disconnecting switch located near the fan. A 2 wire switch leg is pulled from the fan to the 1st closest bathroom switch and another 2 wire from the 1st switch to the 2nd and another 2 wire from the 2nd to the 3rd. The white in the 2 wire is identified with black tape and used as a hot, not a neutral and not the switched hot that connects to the fan.
Keep in mind that these single poles are not 3ways or 4ways meaning that the 1st S1 cannot turn off the fan if the 3rd S1 is in the on position. The fan is off when the disconnect switch (switch 1-2) is on and all 3 S1s are off (switches 3-8, 4-7 and 5-6) The fan is on when the disconnect switch and any one or more of the S1s are also on as shown here;
I hope you found this information useful.