Why build another electrical diagram?
When wiring 3-way and 4-way switch circuits, it's important to include a neutral in every box for smart-switch compatibility. This is not always intuitive when working from existing diagrams which may be older or not designed with neutrals in mind everywhere.
Also, many of the diagrams I found use pictograms or other non-text-based formats that are not easily searchable or accessible. I wanted to create a set of diagrams that are text-based and easy to understand.
If you have feedback or suggestions, please reach out to me on LinkedIn or GitHub.
This is the recommended modern NEC-compliant pattern.
Switch A is the line-side 3-way (power enters here); Switch B is the load-side 3-way (light is fed from here).”
- Power → Switch 1: 14-2 (hot + neutral)
- Switch 1 → Switch 2: 14-3 (two travelers + neutral)
- Switch 2 → Lights: 14-2 (switched hot + neutral)
POWER (Hot + Neutral)
|
v
+------------------+
| 3-WAY SWITCH A |
| |
| Common: LINE |
| Traveler 1 ---- red -----------------------------+
| Traveler 2 ---- black -----------------------+| +
| Neutral ------ white ------------------|----+| +
+------------------+ | +| +
| +| +
+-----|----+|--+---------------------------+
| 3-WAY SWITCH B |
| |
| Traveler 1 ---- red |
| Traveler 2 ---- black |
| Common: LOAD ---+-----> Switched Hot --- black ---> Lights
| Neutral -------------------------------- white ---> Lights
+------------------------------------------+
LOAD / SWITCH BOX TERMINAL MAPPING:
(Brass screws = travelers, black screw = common)
Common (black screw): LINE hot (black from feed 14/2)
Traveler screws (brass):
• red (14/3) → traveler 1 to switch B
• black (14/3) → traveler 2 to switch B
Neutral:
• white (14/3) → spliced together with wirenut joiner (not on switch unless smart)
Ground (green screw):
• bare ground
LIGHT / SWITCH B TERMINAL MAPPING:
(Brass screws = travelers, black screw = common)
Common (black screw): switched hot to lights (black from switch B)
Traveler screws (brass):
• red (14/3) → traveler 1 from switch A
• black (14/3) → traveler 2 from switch A
Neutral:
• white (14/3) → to lights with wirenut joiner use (not on switch unless smart)
Ground (green screw):
• bare ground
Description:
- Neutral in every box (load / switch box + outboard far 3-way)
- Only hot is switched
- Smart-switch compatible
- Matches your original intent
Neutral handling (important):
- Neutral is spliced straight through every box - wirenutted
- It is not landed on 3-way terminals
- Still available for smart switches or future code changes
Now the nice part: nothing fundamental changes.
A 4-way switch only lives between the two 3-ways, and it only touches travelers.
Power → 3-Way A → 4-Way → 3-Way B → Lights
Cabling:
- Power → 3-Way A: 14-2
- 3-Way A → 4-Way: 14-3
- 4-Way → 3-Way B: 14-3
- 3-Way B → Lights: 14-2
POWER (Hot + Neutral)
|
v
+------------------+
| 3-WAY SWITCH A |
| |
| Common: LINE |
| Traveler 1 ---- red -----------------------------+
| Traveler 2 ---- black -----------------------+| +
| Neutral ------ white ------------------|----+| +
+------------------+ | +| +
| +| +
+-----|----+|--+-----------------------------+
| 4-WAY SWITCH |
| |
| IN: Traveler 1 ---- black (14/3) |
| IN: Traveler 2 ---- red (14/3) |
| (4-way X / || crossover) |
| OUT: Traveler 1 ---- black (14/3) |
| OUT: Traveler 2 ---- red (14/3) |
| Neutral: white passes through with joiner |
+--------------------------------------------+
| +| +
+-----|----+|--+---------------------------+
| 3-WAY SWITCH B |
| |
| Traveler 1 ---- red |
| Traveler 2 ---- black |
| Common: LOAD ---+-----> Switched Hot --- black ---> Lights
| Neutral -------------------------------- white ---> Lights
+------------------------------------------+
LOAD / SWITCH BOX TERMINAL MAPPING:
(Brass screws = travelers, black screw = common)
Common (black screw): LINE hot (black from feed 14/2)
Traveler screws (brass):
• red (14/3) → traveler 1 to switch B
• black (14/3) → traveler 2 to switch B
Neutral:
• white (14/2) → spliced together with wirenut joiner (not on switch unless smart)
Ground (green screw):
• bare ground
4-WAY SWITCH TERMINAL MAPPING:
(All screws are travelers)
Traveler IN pair (from 3-way A):
• red (14/3)
• black (14/3)
Traveler OUT pair (to 3-way B):
• red (14/3)
• black (14/3)
Neutral:
• white (14/2) → spliced together with wirenut joiner (not on switch unless smart)
Ground (green screw):
• bare ground
LIGHT / SWITCH B TERMINAL MAPPING:
(Brass screws = travelers, black screw = common)
Common (black screw): switched hot to lights (black from switch B)
Traveler screws (brass):
• red (14/3) → traveler 1 from switch A
• black (14/3) → traveler 2 from switch A
Neutral:
• white (14/2) → to lights with wirenut joiner use (not on switch unless smart))
Ground (green screw):
• bare ground
Description:
- Neutral in every box (load / switch box + 4-way + outboard far 3-way)
- Matches NEC post-2011 intent
- Fully smart-switch compatible
- Scales cleanly to 5-way / 6-way (just repeat the 4-way block)
Neutral handling (important):
- Neutral is spliced straight through every box - wirenutted
- It is not landed on 4-way terminals
- Still available for smart switches or future code changes
Modern code generally expects a neutral available in most switch boxes (with exceptions). These diagrams intentionally include a neutral in every box for smart-switch compatibility.
This topology is:
- ✅ NEC 2011+ compliant
- ✅ Smart-switch safe
- ✅ Dimmer compatible
- ✅ Scales to 5-way, 6-way, etc.
- ✅ Matches commercial wiring practice
- ✅ Avoids switch-loop
- ✅ Avoids re-identification in Scenario 1 to keep things simple
This requires a switch loop meaning each outboard box requires two NM cables:
- 14/3 for travelers + remote common return (white is re-marked hot)
- 14/2 to ensure a neutral in the outboard box
This is the only practical way using common NM (14/2 + 14/3) while keeping a neutral in the outboard box.
NOTE: If you have access to (14/4) cable, you can use that instead to avoid the switch loop. Its hard to find in the market and I usually only find it in "control" cable - stranded without the normal ground. Thats why I didn't include it in the diagrams.
It requires a switch loop and re-identification.
Extra notes and warnings are included below.
POWER (Hot + Neutral)
|
v
+--------------------------------------+
| LOAD / SWITCH BOX |
| (Light + 3-WAY Switch A) |
| |
| Common: LINE <--- hot (black 14/2) |
| Traveler 1 ---- black (14/3) -----------------------------------------------+
| Traveler 2 ---- red (14/3) -----------------------------------------+| +
| Neutral ------ white (14/2) ----------------------------------|----+| +
| | | | +| +
| |----------- white -------------> Lights | +| +
| Hot: |---Hot Return wirenutted to black ---> Lights | +| +
+------ | -----------------------------+ | +| +
| | +| +
| (Switched Hot Return - re-identified black) +-----|----+|------+---------------------+
| | 3-WAY SWITCH B (Outboard Box) |
| | |
| | Traveler 1 ---- black (14/3) |
| | Traveler 2 ---- red (14/3) |
+<--------- white* (14/3) --------------------------| Common: RETURN - white* (14/3) |
| Neutral ------- white (14/2) capped |
+----------------------------------------+
* white in the 14/3 is NOT neutral — it is re-identified as HOT (common return)
LOAD / SWITCH BOX TERMINAL MAPPING:
(Brass screws = travelers, black screw = common)
Common (black screw): LINE hot (black from feed 14/2)
Traveler screws (brass):
• black (14/3) → traveler 1 to Switch B
• red (14/3) → traveler 2 to Switch B
Neutral:
• NOT connected to switch
• Spliced: feed white + light white + (14/2) white to Switch B
Ground (green screw):
• bare ground
OUTBOARD 3-WAY SWITCH B TERMINAL MAPPING:
(Brass screws = travelers, black screw = common)
Common (black screw): white* (14/3) re-identified HOT (common return to light)
Traveler screws (brass):
• black (14/3) → traveler 1 from Switch A
• red (14/3) → traveler 2 from Switch A
Neutral:
• white (14/2) present in box
• capped / parked (or used for smart switch)
Ground (green screw):
• bare ground
LIGHT (in Load/Switch Box) TERMINAL MAPPING:
Hot:
• white* (14/3) ← switched hot return from Switch B
Neutral:
• white (14/2 feed)
Ground:
• bare ground
COLOR USE REMINDER (critical):
14/3 white = HOT (re-identified with tape or marker)
14/2 white = NEUTRAL (never on a switch terminal)
NOTE: Each outboard box requires two NM runs: 14/3 for travelers+return and 14/2 for neutral.
Description:
- Neutral in every box (load / switch box + outboard far 3-way)
- Matches NEC post-2011 intent
- Fully smart-switch compatible
Neutral handling (important):
- Neutral is running on separate 14/2 and spliced through every box
- It is not landed on 3-way terminals
- Still available for smart switches or future code changes
Hot/white re-identification (important):
- White in 14/3 is re-identified as HOT (common return) everywhere
- It is marked with black tape or a permanent marker
- It is not neutral
- It is only landed on Common (black screw) on 3-way switch B
- It is not used for smart switches or dimmers
Again: nothing fundamental changes.
A 4-way switch only lives between the two 3-ways, and it only touches travelers.
Neutral is present in every box and passes straight through 4-way with a wirenut joiner.
Hot/white re-identification happens everywhere and passes through the 4-way with a wirenut joiner.
LOAD / SWITCH BOX (3-WAY A + LIGHT)
|
|-- 14/3 (travelers) + 14/2 (neutral)
v
OUTBOARD BOX #1 (4-WAY)
|
|-- 14/3 (travelers) + 14/2 (neutral)
v
OUTBOARD BOX #2 (3-WAY B)
- 14/3: black + red = travelers, white* = switched-hot return
- 14/2: white = neutral (always unswitched)
- white in 14/3 is re-identified HOT
POWER (Hot + Neutral)
|
v
+--------------------------------------+
| LOAD / SWITCH BOX |
| (Light + 3-WAY Switch A) |
| |
| Common: LINE <--- hot (black 14/2) |
| Traveler 1 ---- black (14/3) -----------------------------------------------+
| Traveler 2 ---- red (14/3) -----------------------------------------+| +
| Neutral ------ white (14/2) ----------------------------------|----+| +
| | | | +| +
| |----------- white -------------> Lights | +| +
| Hot: |---Hot Return wirenutted to black ---> Lights | +| +
+------ | -----------------------------+ | +| +
| | +| +
| (Switched Hot Return - re-identified black) +-----|----+|------+---------------------+
| | 4-WAY SWITCH (Outboard Box #1) |
| | |
| | IN: Traveler 1 ---- black (14/3) |
| | IN: Traveler 2 ---- red (14/3) |
| | (4-way X / || crossover) |
| | OUT: Traveler 1 ---- black (14/3) |
| | OUT: Traveler 2 ---- red (14/3) |
| | |
|<--------- white* (14/3) -----------|---- Switched-hot return (white* 14/3) spliced through |
| | Neutral: white (14/2) spliced through ------|
| +----------------------------------------+ |
| | +| + |
| +-----|----+|------+---------------------+ |
| | 3-WAY SWITCH B (Outboard Box #2) | |
| | | |
| | Traveler 1 ---- black (14/3) | |
| | Traveler 2 ---- red (14/3) | |
|--------------- Common: RETURN - white* (14/3) | |
| Neutral ------- white (14/2) capped ---------|
+----------------------------------------+
* white in the 14/3 is NOT neutral — it is re-identified as HOT (common return)
LOAD / SWITCH BOX TERMINAL MAPPING:
(Brass screws = travelers, black screw = common)
(3-WAY A + Light + Feed)
Common (black screw): LINE hot (black from feed 14/2)
Traveler screws (brass):
• black (14/3) → traveler to 4-way
• red (14/3) → traveler to 4-way
Neutral:
• NOT on switch
• Splice: feed white + light white + (14/2) white to Box #1
Switched Hot:
• light hot + (14/3) white* (return from Box #1 / 3-way B in Box #2)
Ground (green screw):
• all bare grounds tied + switch yoke
OUTBOARD BOX #1 TERMINAL MAPPING:
(4-WAY SWITCH)
(All screws are travelers)
Traveler IN (pair):
• black (14/3) from Box A
• red (14/3) from Box A
Traveler OUT (pair):
• black (14/3) to Box B
• red (14/3) to Box B
Neutral:
• (14/2) white present
• spliced THROUGH (or used for smart switch)
Switched-hot return:
• (14/3) white* spliced THROUGH (not landed) re-identified HOT
Ground (green screw):
• bare ground + yoke
OUTBOARD BOX #2 TERMINAL MAPPING:
(Brass screws = travelers, black screw = common)
(3-WAY SWITCH B)
Common (black screw): white* (14/3) re-identified HOT (switched-hot return to light via Box #1 )
Traveler screws (brass):
• black (14/3) → traveler from 4-way
• red (14/3) → traveler from 4-way
Neutral:
• (14/2) white present
• capped / parked (or smart switch)
Ground (green screw):
• bare ground + yoke
LIGHT (in Load/Switch Box) TERMINAL MAPPING:
Hot:
• white* (14/3) ← switched hot return re-identified HOT wirenutted to black
Neutral:
• white wirenutted to (14/2) feed + (14/2) white from Box #1
Ground:
• bare
COLOR USE REMINDER (critical):
14/3 white = HOT (re-mark all ends)
14/2 white = NEUTRAL (never on a switch terminal)
4-way switch never sees line, load, or neutral — travelers only
NOTE: Each outboard box requires two NM runs: 14/3 for travelers+return and 14/2 for neutral.
Description:
- Neutral in every box (load, 4-way, far 3-way)
- Matches NEC post-2011 intent
- Fully smart-switch compatible
- Scales cleanly to 5-way / 6-way (just repeat the 4-way block)
Neutral handling (important):
- Neutral is running on separate 14/2 and spliced through every box
- It is not landed on 3-way terminals
- Still available for smart switches or future code changes
Hot/white re-identification (important):
- White in the 14/3 is re-identified as HOT (common return).
- It is landed only on the COMMON (black screw) of the far 3-way switch and is spliced through all other boxes.
- It is never used as a neutral.