Quick answer
An electrical panel is the metal box where power from the utility enters a home and is divided into separate circuits, each protected by its own circuit breaker or fuse.
Makers call the residential version a load center; people also say breaker box or service panel. Its amp rating and the number of spaces set how much load and how many circuits the home can have.
Quick facts
The key facts about Electrical Panel, with sources:
- Also called
- Load center, breaker box, service panel, panelboard
- Typical home supply
- 120/240-volt, single-phase
- Key ratings
- Bus amp rating, main breaker size, number of spaces and circuits
- Main parts
- Main breaker, busbars, branch breakers, neutral and ground bars
- Workplace clear width
- At least 30 inches or the equipment width (OSHA 1910.303) 3
- Workplace headroom (installed on or after 13 Aug 2007)
- 6.5 feet 3
Key takeaways
- The panel is the hub of a home's wiring: power comes in, splits into circuits and each circuit gets a breaker.
- "Load center" is the industry name for a home breaker panel; it is the same equipment.
- Its amp rating limits total load, and its spaces limit how many circuits fit.
- Owners can read labels and reset a tripped breaker once; everything inside the cover is electrician work.
- Adding big loads like an EV charger or heat pump often starts with a panel check.
What an electrical panel is
Electricity from the utility runs through transformers and distribution lines that bring it down to a safe voltage for homes 1. It then passes through your meter and into the panel. From there it goes out on branch circuits to outlets, lights and appliances.
Every circuit starts at a circuit breaker in the panel, or a fuse in older homes. The breaker trips if the circuit draws too much current or has a fault. Most panels also have a main breaker that shuts off the whole house.
Load center, breaker box or panel: one thing
Manufacturers sell residential panels as "load centers". Square D, for example, markets its Homeline line as load centers that take 1-inch Homeline breakers 2. Electricians, inspectors and homeowners say "panel", "breaker box" or "service panel". All describe the same box.
Strictly, "panelboard" is the broader code term, used for heavier commercial boards too. A "subpanel" is a second panel fed from the main one. If a quote says "replace load center", it means replace the panel.
How a panel distributes power
Most US homes get 120/240-volt single-phase service. Two hot service wires land on the main breaker, which feeds two metal busbars running down the panel. Breakers snap onto the busbars. A single-pole breaker takes one bar and makes a 120-volt circuit. A double-pole breaker takes both and makes a 240-volt circuit.
Neutral wires return to a neutral bar. Ground wires go to a ground bar, which ties to the grounding electrode. In the main panel, neutral and ground are bonded together at one point. In a subpanel, they are kept apart.
Some newer panels use a plug-on neutral design, where breakers clip straight onto a neutral rail. Square D describes its version as having a fully distributed neutral bar, which it presents as a time saver during installation, on enclosures of 8 spaces and up 2.
- Utility transformersteps voltage down
- Service drop or lateralwires to the house
- Metermeasures use
- Main breakerwhole-house disconnect
- Busbarscarry power inside the panel
- Branch breakersone per circuit
- Circuitsoutlets, lights, appliances
Source: [1]
- Main breakershuts off all circuits
- Busbarshot bars breakers attach to
- Branch breakersprotect each circuit
- Neutral barwhite wires return here
- Ground barbare and green wires
- Dead front and doorcovers live parts
- Panel directorylabels each circuit
Types of panels you may find
| Type | What it is | Where it is used |
|---|---|---|
| Main breaker panel | Panel with its own main breaker | Most homes; main service panel |
| Main lug panel | No main breaker; fed from a breaker elsewhere | Subpanels, or where the disconnect is at the meter |
| Meter-main combo | Meter socket and main breaker in one unit | Outdoor service, often with an indoor subpanel |
| Subpanel | Second panel fed by a feeder from the main | Garages, additions, basements |
| Fuse box | Uses screw-in or cartridge fuses | Older homes |
| Smart panel | Panel with circuit-level monitoring or control | Electrification and solar/battery homes |
| Critical loads panel | Subpanel for circuits kept on during outages | Generator and battery systems |
Example: reading a panel label
The label inside the door, and the markings on the breakers, tell you most of what an electrician will ask. Reading them is safe. Removing the inner cover is not.
| Where to look | What you see | What it tells you |
|---|---|---|
| Main breaker handle | 200 | The service is likely 200 amps |
| Label "bus rating" | 225 A | The most the busbars can carry |
| Label "spaces / circuits" | 40 spaces, 40 circuits | Tandem breakers may not be allowed |
| Label "accepts types" | A list of breaker models | Only listed breakers belong here |
| Door directory | Kitchen, dryer, furnace… | Which breaker feeds what |
| Manufacturer and model | Brand and catalog number | Lets an electrician spot recalled or problem brands |
Our guide to finding your service size shows where these markings sit. The panel space tool helps you count free slots.
Where the panel is in a home
Panels are usually in a garage, basement, utility room or hall closet, often on the wall nearest the meter. Some homes have the main breaker outside at the meter and a breaker panel inside.
Code requires clear space in front of panels so they can be reached and worked on.
For workplaces, OSHA requires a working space at least 30 inches wide, or the width of the equipment if greater, and 6.5 feet of headroom for installations built on or after 13 August 2007 3.
Homes follow the NEC's own working-space rule. Do not store boxes or build shelves in front of the panel.
Label it
An accurate circuit directory saves time in an outage or emergency. OSHA requires disconnects in workplaces to be legibly marked for their purpose 3; at home it is simply good sense.
What a good panel gives you
- Protection for each circuit's wiring from overloads and faults.
- One place to shut off power in an emergency.
- Room for new loads such as an EV charger or heat pump.
- Modern protection such as AFCI, GFCI and whole-home surge protection in compatible panels.
What a panel cannot do
- A panel cannot exceed the service the utility provides; a bigger box does not mean more power.
- It cannot protect wire that has the wrong breaker on it.
- It only accepts the breaker types listed on its label.
- Free spaces do not prove there is spare capacity; a load calculation does.
What drives panel cost
Replacing or upgrading a panel is priced by amp rating, number of spaces, whether the service wires and meter also change, utility coordination, permit fees, and wall repairs. Moving a panel costs more than replacing it in place. Upgrades to 200 amps often involve the utility.
Panel upgrade pricing has its own page: see panel upgrade cost and our panel upgrade cost research. Panels are long-lived equipment, but breakers and connections wear, and some older brands have known problems.
How panel work happens
The steps a licensed electrician follows for a panel replacement or panel upgrade. This is for understanding, not doing.
- Inspect the existing panel, service and grounding.
- Run a load calculation to size the new panel.
- Pull a permit and, if the service changes, schedule a utility disconnect.
- Install the panel, move circuits, add required AFCI/GFCI protection and label every breaker.
- Pass inspection; the utility reconnects and reseals the meter if it was pulled.
See how permits work.
What owners can safely do
- Keep the area in front of the panel clear and dry.
- Keep the circuit directory current.
- Reset a tripped breaker once: push it fully off, then on. If it trips again, leave it off and call an electrician.
- Press TEST on GFCI and AFCI breakers as the maker advises.
- Never remove the inner cover (dead front). Live parts sit behind it.
Panel warning signs
Safety and risk
A hot panel door, buzzing or crackling, scorch marks, a burning smell, rust or water inside, or breakers that will not stay reset are reasons to call a licensed electrician promptly. Do not open the inner cover.
If there is smoke, sparking or fire, leave the house and call 911. For a panel that has been under water, call the utility to disconnect power first.
Problems found in older panels
- Brands with known reliability concerns, such as some Zinsco and Federal Pacific panels.
- Double-tapped breakers: two wires under a screw made for one.
- Breakers from another brand that are not listed for the panel.
- Fuses oversized for the wire they protect.
- Overcrowded panels with no room for required protection.
Our research on hazard-era panels covers brands and dates.
Code and standards
Panels and their installation fall under NFPA 70, the National Electrical Code 4. The 2023 edition covers panelboards in Article 408, overcurrent protection in Article 240, service equipment in Article 230 and working space in Section 110.26. Breakers are tested to UL 489, and panels are listed with the breaker types they accept.
States and cities adopt NEC editions on their own schedule 5. Anyone can read the NEC free on NFPA's site 6. Workplaces must also meet OSHA 29 CFR 1910.303 3.
Panel compared with related equipment
| Equipment | Job | Relationship to the panel |
|---|---|---|
| Electrical panel / load center | Splits power into protected circuits | The hub |
| Meter base | Holds the utility meter | Upstream of the panel |
| Main breaker | Shuts off and protects the whole panel | Inside the panel or at the meter |
| Subpanel | Adds circuits in another area | Fed from the main panel |
| Transfer switch | Switches between grid and generator | Next to or part of the panel |
| Disconnect switch | Shuts off one piece of equipment or the service | Separate from or ahead of the panel |
Myths about electrical panels
- Myth Empty spaces mean I can add anything.
- Reality Spaces are slots; capacity comes from a load calculation.
- Myth A 200-amp panel means 200-amp service.
- Reality The service is set by the utility feed and service wires, not the box alone.
- Myth Any breaker that fits is fine.
- Reality Only breakers listed on the panel label belong in it.
- Myth A load center is a different thing from a panel.
- Reality It is the maker's name for a home breaker panel.
- Myth Turning off the main makes the panel safe to open.
- Reality The wires feeding the main stay live.
Rules that vary by state
Which NEC edition applies, when a panel swap needs a permit, and who may do it depend on your state or city 5. Utilities also set their own rules for meter pulls and service upgrades.
When your panel matters
Your panel matters when you add a major load, when breakers trip often, when an inspection flags the brand or condition, or when it is full. A panel upgrade is not always the answer: load management or a subpanel can work.
Next step: check your loads with the load calculator and EV plans with the EV charger readiness tool, then ask a licensed electrician for an assessment.
- If Adding EV charger, heat pump or range
- Then Run a load calculation first
- If Panel full but capacity left
- Then Subpanel or circuit changes may work
- If Known problem brand or damage
- Then Get it assessed for replacement
- If Breakers trip often
- Then Have an electrician find why
Questions about Electrical Panel
Is a load center the same as an electrical panel?
Yes. "Load center" is the name manufacturers use for a residential breaker panel. Electricians and homeowners call the same box a panel, breaker box or service panel.
Strictly, "panelboard" is the broader code term that also covers heavier commercial boards. Square D, for example, sells its Homeline residential panels as load centers that take 1-inch Homeline breakers 2.
How do I know what size my electrical panel is?
Look at the number on the main breaker handle and the rating label inside the panel door. The main breaker often shows the service size, such as 100 or 200 amps. The label lists the bus rating, which may be higher. Do not remove the inner cover. Our service size guide shows where to look.
How long does an electrical panel last?
There is no single lifespan. Panels are durable, but breakers, connections and busbars wear with heat, moisture and use. Panels from some older brands have known problems. An electrician can judge condition during an inspection.
Rust, water stains, scorch marks or breakers that will not stay reset are signs that a panel is near the end of its useful life, whatever its age.
What is the difference between a main panel and a subpanel?
The main panel receives power from the utility and holds the main disconnect. A subpanel is fed from a breaker in the main panel and adds circuits in another area.
In a subpanel, neutral and ground bars are kept separate. A subpanel cannot supply more than the main panel feeding it, so it adds circuits, not total capacity.
Can I add more breakers to my panel?
Only if it has free spaces, the panel accepts the breaker type, and a load calculation shows capacity. Some panels allow tandem breakers in certain slots.
Adding a breaker means working inside the panel, which is electrician work and often needs a permit.
The breaker types a panel accepts are printed on its label, so a photo of that label helps an electrician quote the job.
Why is my electrical panel warm?
A slightly warm door can be normal under heavy load. A hot door, a burning smell, buzzing or discoloration is not. Those signs can point to loose connections or overloaded breakers.
Call a licensed electrician, and call 911 if you see smoke or flame. Until the electrician arrives, turn off large loads such as space heaters or the dryer if you can do so without opening the panel.
Do I need a permit to replace an electrical panel?
In most places, yes. Panel replacement usually needs a permit and inspection, and service changes need utility coordination. Rules vary by city and state.
A licensed electrician normally pulls the permit as part of the job.
If the meter must be pulled, the utility schedules a disconnect and a reconnect after the inspection passes, which can add days to the timeline.
What does it mean when a breaker keeps tripping?
A breaker that keeps tripping means the circuit is overloaded, has a short or ground fault, or the breaker is failing. Reset it once. If it trips again, unplug loads on that circuit and call an electrician.
Never replace it with a larger breaker. The breaker is sized to protect the wire behind it, so a bigger one can let that wire overheat without tripping.
Should I upgrade to a 200-amp panel?
A 200-amp upgrade makes sense only if your loads need it. Homes adding EV charging, heat pumps or electric cooking may need more capacity, but a load calculation decides.
Load management or a smart panel can sometimes avoid an upgrade. See our panel upgrade page for options. Bring a list of planned appliances with their nameplate amps, so the electrician can run the numbers instead of guessing.
Where should an electrical panel be located?
Usually in a garage, basement, utility room or closet near the meter, with clear working space in front. Code limits places such as bathrooms and clothes closets.
An electrician decides placement under your local code. For workplaces, OSHA requires clear working space at least 30 inches wide, or the equipment width if greater, in front of the panel 3.
Sources
- U.S. EIA, Electricity explained: delivery to consumers, retrieved .
- Schneider Electric (Square D), Homeline Plug-on Neutral load centers, retrieved .
- OSHA, 29 CFR 1910.303 General requirements (electrical), retrieved .
- NFPA, NFPA 70 (National Electrical Code) code development page, retrieved .
- NFPA, Where the NEC is enforced (adoption maps), retrieved .
- NFPA, Free access to NFPA codes and standards, 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: Working-space figures read from OSHA 1910.303; panel design from the manufacturer page; delivery path from EIA; NEC articles named by edition. No prices (G-COST).
Suggest a correction. We fix errors and say what changed.