Quick answer
A neutral wire is the circuit conductor, usually white or gray, that carries current back from lights and appliances to the panel and the utility transformer, and is connected to earth at the service so it stays near zero volts to ground.
The NEC calls it the grounded conductor. It carries current whenever a 120-volt load runs, so it can shock you, and it must never be used as a safety ground or joined to ground anywhere except the service.
Quick facts
The key facts about Neutral Wire, with sources:
- Color
- White or gray insulation (NEC 200.6) 2
- Terminal
- The silver screw on a receptacle; white on device leads 7
- Grounded where
- At the utility transformer and the building service entrance 5
- Carries current
- Yes, whenever a 120 V load runs
- At switches
- NEC 404.2(C) (2023): a neutral at switches controlling lighting in listed rooms, with exceptions 1
Key takeaways
- The neutral is the return path for current in a 120-volt circuit.
- It is white or gray, and it is grounded at the service so it stays near zero volts to ground.
- It carries current in normal use, so it can shock you; it is not a ground wire.
- Neutral and ground are joined only at the service, never downstream.
- A lost or loose neutral can cause flickering, dim and bright lights, and damaged electronics.
What the neutral wire is
Every circuit is a loop: current leaves the panel on the hot wire, passes through the light or appliance, and returns on the neutral. Without the neutral, a 120-volt load has no way back and will not run.
The NEC’s term is the grounded conductor, because it is connected to earth at the service. EC&M notes the grounded conductor is usually, but not always, the neutral 3. OSHA’s grounding guide says the neutral is grounded at the transformer and at the building’s service entrance 5.
Being grounded means it sits near zero volts to the earth, but that does not make it safe to touch, because when current flows the neutral is part of a live circuit.
Neutral vs ground
The neutral carries normal return current all the time, while the ground wire carries current only during a fault. They meet at one place, the service panel, and must be kept apart everywhere else.
How the neutral works in a 120/240-volt home
US homes get two hot legs and one neutral from the utility transformer. Each hot leg is 120 volts to the neutral, and the two hots are 240 volts to each other.
Lights and outlets use one hot and the neutral, while a 240-volt load such as a water heater may use only the two hots.
When loads on the two legs are balanced, their return currents cancel on the shared neutral. When they are unbalanced, the neutral carries only the difference, which is why a shared service neutral can be smaller than the hots in some cases.
Utilities step voltage down at transformers before it reaches homes; the EIA describes how distribution lines carry lower-voltage power that is safer to use in homes 8.
I(neutral) = | I(leg A) − I(leg B) |
I(leg A)- 120 V load current on the first hot leg
I(leg B)- 120 V load current on the second hot leg
I(neutral)- Current returning on the shared neutral
Applies to 120 V loads on opposite legs of a 120/240 V single-phase service.
Why polarity matters
Polarity means the hot and neutral are on the right terminals, so on a receptacle the neutral belongs on the silver screw and the long slot 7. Polarized plugs have one wide blade so the lamp or appliance connects the same way every time.
That matters because switches cut the hot, not the neutral. In a lamp wired with correct polarity, the threaded metal shell of the socket connects to the neutral, and turning the lamp off removes voltage from the center contact.
Reverse the wires and the shell you might touch while changing a bulb can stay live even with the lamp switched off.
A cheap plug-in tester can flag reversed polarity, and if it does, stop using that outlet and call an electrician.
Example: what the service neutral carries
An illustration of the formula above with round numbers for 120 V loads on a 120/240 V service.
| Leg A load | Leg B load | Neutral current |
|---|---|---|
| 10 A | 10 A | 0 A (balanced) |
| 10 A | 6 A | 4 A |
| 12 A | 0 A | 12 A |
| 20 A 240 V water heater on both legs | Same 20 A | 0 A from that load |
This is why a lost service neutral is so damaging: with no return path, the two legs share 240 volts in proportion to their loads, so one side of the house can see high voltage while the other sees low. See open neutral.
Where neutrals appear
| Neutral | Where | Notes |
|---|---|---|
| Service neutral | From the utility to the main panel | Bonded to ground at the service only |
| Branch circuit neutral | White wire in each 120 V circuit | Returns current from that circuit |
| Shared (multiwire) neutral | One neutral serving two hots on opposite legs | Needs a handle-tied or two-pole breaker |
| Switch-box neutral | A neutral run into the light switch box | Required at most lighting switches 6 |
| Re-identified white wire | White used as a hot in some cable runs | Must be re-marked with a color other than white, gray or green |
Where you see the neutral
In cables it is the white wire, and in the panel neutrals land on a neutral bar. On a receptacle, the neutral goes on the silver screw, and the long slot connects to it 7.
In light switch boxes, the neutral is often a bundle of white wires joined at the back.
Smart switches need it to stay powered in standby; NEC 404.2(C), in the 2023 edition too, requires a neutral at switches controlling lighting in listed rooms, with exceptions 1; under the 2017 text the connection rule took effect January 1, 2020 6. For more, see smart light switch.
- Utility transformerGrounded at the source 5
- Service panelNeutral bar, bonded to ground here only
- ReceptaclesSilver screw, long slot
- Light fixturesWhite lead
- Switch boxesFor smart and electronic controls
What a sound neutral gives you
- Steady 120 volts on every outlet.
- A return path that keeps lights steady when big loads start.
- Correct polarity, so switches cut the hot and lamp shells are not live.
- Standby power for smart switches and timers 6.
What the neutral is not
A neutral wire is not a safety ground, and joining neutral and ground downstream of the service puts normal current on ground wires, metal boxes and pipes. That defeats the purpose of the grounding system and can trip GFCIs.
It is not always dead, because a neutral can carry current from other circuits, especially a shared neutral, even when the light you are working on is off.
What drives the cost of neutral problems
We do not print prices. A loose neutral at one outlet is a small repair.
A failing service neutral may be the utility’s job if it is on their side of the meter, or an electrician’s if it is in the panel or service conductors.
Running new neutrals to switch boxes costs more in finished walls. See the project cost tool and emergency electrician service.
How an electrician tracks down a neutral problem
Neutral faults can put dangerous voltage on circuits, so this is work for a licensed electrician and, at the service, the utility.
- Measure voltage on each leg and from neutral to ground at several outlets.
- Check whether symptoms affect the whole house or one circuit.
- Inspect connections at the panel neutral bar and suspect devices.
- If the service neutral is suspect, call the utility.
- Repair, re-terminate and retest.
Owner checks
Warning signs of a neutral problem
Lights that get brighter when a large appliance starts, flickering across many rooms, electronics failing, a burnt smell at the panel or outlets, or a tingle from appliances can all point to a loose or lost neutral.
Bright and dim lights mean act now
If some lights go very bright while others dim, unplug sensitive electronics and call the utility and an electrician right away. A lost service neutral can push one leg well above 120 volts, so do not open the panel.
Code rules
The NEC requires insulated grounded conductors to be white or gray (200.6), and bars white, gray and green from use as hots, with limited re-identification rules (200.7) 2.
Neutrals at lighting switch locations in listed rooms are required by 404.2(C) in the 2023 edition, with exceptions 1; the 2017 text also exempts some replacements and caps no-neutral electronic controls at five per branch circuit 6.
Neutral and equipment ground are bonded together only at the service by the main bonding jumper, under NEC Article 250 4, and states adopt and amend the NEC on their own schedule.
Neutral compared with other conductors
| Conductor | Color | Normal current? | Purpose |
|---|---|---|---|
| Hot | Black, red, others | Yes | Brings power to the load |
| Neutral | White or gray | Yes | Returns current to the source |
| Equipment ground | Bare or green | No | Fault path to trip the breaker |
| Bonding jumper | Bare or green | No | Joins metal parts and, at the service, neutral to ground |
Myths about the neutral
- Myth The neutral cannot shock you.
- Reality It carries current and can shock you, especially if it is open.
- Myth Neutral and ground are the same thing.
- Reality They are joined only at the service and do different jobs 4.
- Myth You can use the ground as a neutral for a smart switch.
- Reality Never; that puts current on metal parts.
- Myth A white wire is always a neutral.
- Reality In some cable runs a white wire is re-marked and used as a hot 2.
Code edition and older homes
What to do about neutral symptoms
Match the symptom to the response.
- If Lights brighten and dim across the house
- Then Call the utility and an electrician now
- If One outlet or light flickers
- Then Stop using it; call an electrician
- If Want a smart switch, no neutral in box
- Then Ask about a no-neutral model or running a neutral
- If GFCI trips with nothing plugged in
- Then Ask an electrician to check for a neutral-to-ground fault
Note the pattern
Tell the electrician which rooms are affected and whether symptoms change when big appliances start, since that points straight to a branch or service neutral.
Questions about Neutral Wire
What does the neutral wire do?
It carries current back from lights and appliances to the panel and the utility transformer, completing the circuit, and without it a 120-volt load cannot run.
Can a neutral wire shock you?
Yes. It carries current whenever a load is running, and an open or loose neutral can rise to a dangerous voltage. Treat every wire as live; only a licensed electrician should work on wiring.
What color is the neutral wire?
White or gray, as required by the NEC, although in some older cable runs a white wire was used as a hot and should be re-marked with tape or paint of another color.
What is the difference between neutral and ground?
The neutral carries normal return current, and the ground carries current only during a fault, to trip the breaker. They are bonded together only at the main service panel.
Why do smart switches need a neutral?
Their electronics stay on all the time to listen for commands, and that standby power needs a return path. The NEC has required a neutral at most lighting switch locations to support these devices.
What happens if the neutral wire is loose?
Lights may flicker or change brightness, outlets may stop working, and connections may heat up. A loose service neutral can push some circuits well above 120 volts and damage electronics, so call an electrician promptly.
Why is the neutral bonded to ground at the panel?
So that a fault on a metal part has a low-impedance path back to the source through the neutral, which trips the breaker, while bonding them anywhere else would put normal current on ground wires.
Does a 240-volt appliance need a neutral?
Some do and some do not: a water heater may use only two hots and a ground, but a range or dryer that also has 120-volt parts, like a clock or light, uses a neutral too. The appliance’s instructions say which.
Can two circuits share a neutral?
Yes, in a multiwire branch circuit with hots on opposite legs, protected by a handle-tied or two-pole breaker so both turn off together, and this is design work for an electrician.
How do I find the neutral in a switch box?
Do not open the box. An electrician will look for a bundle of white wires joined at the back, though some older switch boxes have no neutral at all.
Sources
- Electrical Association (Minneapolis), 2023 NEC Update Part 3 training slides, 404.2(C) Switches Controlling Lighting Loads, retrieved .
- EC&M, Code Q&A: NEC Requirements for Conductor Identification (2023), retrieved .
- Mark Lamendola, EC&M, Understanding NEC Definitions for Grounding (May 2024), retrieved .
- Randy Barnett, EC&M, 10 Sure Ways to Tell the Difference Between Bonding & Grounding (Aug 2022), retrieved .
- OSHA Construction eTool, Electrical Incidents: Grounding, retrieved .
- Leviton Captain Code (NEC 2017), 404.2(C) Switches Controlling Lighting Loads, retrieved .
- Leviton, T5835-W 20A Tamper-Resistant USB Receptacle specifications (terminal identification), retrieved .
- US EIA, Electricity explained: Delivery to consumers, retrieved .
- US CPSC, Home Electrical Safety Checklist (Pub 513), retrieved .
- Texas Department of Licensing and Regulation, 2023 National Electrical Code is almost here, retrieved .
- Washington State Register WSR 25-23-069 (L&I adopts the 2026 NEC), retrieved .
Expert review
Written by the HyreElectrical Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: Conductor names and colors follow EC&M on NEC 200.6, 200.7 and Article 100; grounding of the neutral follows OSHA; switch-box neutrals follow 2023 NEC update training slides and Leviton’s 2017 404.2(C) guide; terminal marking follows the Leviton T5835 data sheet.
The neutral-current example is labeled arithmetic, and the page carries no DIY wiring and no prices under G-COST.
Suggest a correction. We fix errors and say what changed.