Plain-English Definitions From a Licensed Electrician
Electrical Glossary for Florida Homeowners
The terms that show up on your 4-point inspection, your generator quote and your panel label, explained the way we would explain them in your garage.
AFCI (Arc-Fault Circuit Interrupter)
A breaker or outlet that detects the electrical signature of an arc, the sparking that starts fires inside walls, and shuts the circuit off. Required by the current code on most bedroom, living-area and hallway circuits in new work and panel replacements.
Aluminum branch wiring
Solid aluminum wire used for ordinary 15 and 20 amp circuits in homes built roughly 1965 to 1975. It expands, contracts and oxidizes at connections, which loosens them and causes overheating. Remediated with approved connectors (AlumiConn, COPALUM) or replaced.
Amp (ampere)
The measure of electrical current. A home's service size, 100, 150 or 200 amps, is the maximum the panel and utility feed can deliver at once.
Automatic transfer switch (ATS)
The device that senses a utility outage, starts a standby generator and switches the home's circuits to it, then switches back when power returns. Standby generators use an ATS; portables use a manual transfer switch or interlock.
Bonding
Connecting metal parts that could become energized, gas piping, water piping, pool steel, dock frames, so they are at the same electrical potential and a fault trips the breaker instead of shocking someone.
Breaker (circuit breaker)
An automatic switch that opens a circuit when current exceeds its rating, protecting the wire from overheating. A breaker that trips is doing its job; one that trips repeatedly is telling you something.
Challenger / Sylvania / Zinsco / Federal Pacific (FPE) panels
Panel brands from the 1960s to 1980s with documented failure modes: breakers that do not trip under fault, bus bars that overheat. Most Florida insurers flag them on a 4-point inspection and many require replacement.
Dedicated circuit
A circuit serving a single appliance or load, such as an EV charger, range, dryer, microwave, well pump or mini-split, with nothing else connected.
Double-tap
Two wires landed under one breaker terminal that is rated for one. A common inspection finding that overheats and loosens; fixed by adding a breaker or a listed tap device.
EVSE (Electric Vehicle Supply Equipment)
The proper name for an EV charger. Level 1 uses an ordinary 120 V outlet; Level 2 uses a 240 V circuit, typically 40 to 60 amps, and adds roughly 25 to 45 miles of range per hour.
4-point inspection
A Florida insurance inspection of the roof, plumbing, HVAC and electrical on homes usually over 25 to 30 years old. The electrical section records panel brand, service size, wiring type and hazards; a failed section can mean non-renewal.
GFCI (Ground-Fault Circuit Interrupter)
A breaker or outlet that trips in milliseconds when current leaks to ground, for example through a person. Required in kitchens, bathrooms, garages, outdoors, laundry and anywhere near water.
Grounding electrode system
The ground rods, water-pipe bond and rebar (Ufer) connection that tie the electrical system to the earth so surges and faults have a safe path.
Interlock kit
A listed mechanical slide on a panel cover that prevents the main breaker and a generator back-feed breaker from being on at the same time. A lower-cost alternative to a manual transfer switch for portable generators.
Knob-and-tube
Ungrounded wiring from before roughly 1940, with ceramic insulators. Rare in Tampa Bay but present in some historic Ybor, Seminole Heights and St. Petersburg homes; insurers generally will not cover it.
Load calculation
The NEC method of adding up a home's lighting, appliance, HVAC and motor loads to size the service, the panel, a generator or a new feeder correctly.
Main breaker
The large breaker at the top of the panel that disconnects the entire home. In newer code, an outdoor emergency disconnect is also required so firefighters can cut power from outside.
Meter can / meter base
The utility-owned meter sits in a homeowner-owned enclosure on the outside wall. Corroded or storm-damaged meter cans are a common coastal repair and must be fixed before the utility will reconnect.
NEC (National Electrical Code)
The code Florida adopts (with amendments) as part of the Florida Building Code. Florida currently enforces the 2023 NEC; inspectors check our work against it.
Neutral
The grounded conductor that carries current back to the source. A lost or loose neutral causes lights to go very bright and very dim and destroys electronics; it is an emergency.
Permit
Authorization from the county or city building department for regulated electrical work, followed by an inspection. Required for panels, services, generators, EV circuits, new circuits and rewires.
Service upgrade
Replacing the meter base, main disconnect, panel and often the feed to increase a home's capacity, commonly from 100 or 150 amps to 200 amps, coordinated with the utility.
Soft-start kit
A device on an air-conditioner compressor that reduces its start-up surge so a smaller generator can run it.
Standby generator
A permanently installed generator, usually natural gas or propane, that starts automatically during an outage through an automatic transfer switch.
Subpanel
A secondary panel fed from the main panel, used to add circuits in a garage, addition, workshop, dock or pool area.
Surge protective device (SPD)
A whole-home surge protector mounted at the panel (Type 1 or Type 2) that clamps voltage spikes from lightning and utility switching before they reach appliances and electronics.
Three-phase power
Commercial and industrial service with three alternating voltages, used for large motors, HVAC and equipment. Most homes are single-phase.
Weatherhead and service mast
The pipe and cap on the roof or wall where the utility's overhead wires attach. Storm damage here is a homeowner repair, and the utility will not reconnect until it is fixed and inspected.
Back-feeding
Connecting a generator to the house through an outlet (the dangerous 'suicide cord') so it energizes the utility lines. Illegal, can electrocute line workers, and destroys the generator when power returns. A transfer switch or interlock prevents it.
Carbon monoxide (CO)
The odorless gas produced by generator and gas-appliance exhaust. The leading cause of post-hurricane deaths in Florida. Generators belong outdoors, 20 feet from the house; battery CO alarms belong on every level.
Conduit (EMT, PVC, LFMC)
The metal or plastic tubing that protects wires. EMT is the thin-wall steel used in commercial work; PVC is used underground and outdoors; liquidtight flexible conduit connects equipment such as AC condensers and pool pumps.
Emergency disconnect
An outdoor switch required on new and replaced services by the current code so first responders can de-energize the house from outside.
Equipotential bonding (pools)
Bonding the pool shell steel, deck, ladders, lights, pump and nearby metal into one grid so a swimmer never bridges two different voltages. Required by NEC Article 680 and inspected on every pool job.
Feeder
The conductors that carry power from the main panel to a subpanel, a detached building, a dock or a large piece of equipment.
Level 1 / Level 2 / DC fast charging
Level 1 is a 120 V outlet (3 to 5 miles of range per hour). Level 2 is a 240 V circuit (25 to 45 miles per hour), the standard home install. DC fast charging is commercial equipment that converts to DC at the station and adds hundreds of miles per hour.
Lost neutral (open neutral)
A broken or loose neutral at the panel, the meter or the utility connection. Voltage on the two legs of the home becomes unbalanced; lights go very bright and very dim, and electronics fail. An emergency.
Megger / insulation test
A test that applies a high voltage to wiring to measure insulation resistance. Used to evaluate old wiring, flooded wiring and motor windings.
Short circuit vs. overload vs. ground fault
An overload is too much load on a circuit (a space heater and a microwave on one 15-amp circuit). A short is a direct contact between hot and neutral. A ground fault is current leaking to ground or to a person. Breakers handle the first two; GFCIs handle the third; AFCIs handle arcs.
Single-pole / double-pole breaker
A single-pole breaker serves a 120 V circuit (lights, outlets). A double-pole breaker spans both legs for a 240 V circuit (range, dryer, AC, EV charger, well pump).
Tandem (cheater) breaker
A breaker that fits two circuits in one slot. Permitted only in slots the panel label allows; used elsewhere it is an inspection finding and a sign the panel is out of room.
Type 1 / Type 2 SPD
Surge protector categories. Type 1 installs on the line side of the main (at the meter); Type 2 installs at the panel on the load side. Either satisfies the current code's requirement on new and replaced services.
Voltage drop
The loss of voltage over a long wire run. Matters on docks, detached garages, well pumps and long EV charger runs; fixed by upsizing the conductors.
Wire gauge (AWG)
Wire size. Smaller numbers are bigger wires: 14 AWG for 15-amp circuits, 12 for 20, 10 for 30, 8 for 40, 6 for 50 to 60 (EV chargers, ranges), 4/0 aluminum or 2/0 copper for a 200-amp service.
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