Components | VoltCheck

Circuit Breaker

Protection

Automatically interrupts a circuit on overload or short circuit.

Specs: Ratings: 15A, 20A, 30A, 50A, etc. Single-pole (120V) and double-pole (240V).

Tip:Size to wire ampacity. A breaker that won't stay reset likely protects a fault — find the fault, don't just keep resetting.

GFCI Outlet

Protection

Ground Fault Circuit Interrupter trips when current leaks to ground (shock protection).

Specs: Required in kitchens, baths, garages, outdoors, and near water.

Tip:Press TEST monthly. Protects downstream 'load' outlets when wired correctly (LINE vs LOAD).

AFCI Breaker

Protection

Arc Fault Circuit Interrupter detects dangerous arcing that can cause fires.

Specs: Required for bedroom and most living-area circuits in modern codes.

Tip:Trips on series/parallel arcs. Nuisance trips can come from old motors or damaged cords.

Standard Receptacle

Wiring

15A or 20A general-purpose outlet.

Specs: NEMA 5-15R (120V). Use side screws, not backstab holes, for reliable contact.

Tip:Hot to brass, neutral to silver, ground to green. Replace if contacts are loose or discolored.

Switch

Control

Single-pole, 3-way, or 4-way switch for lighting and loads.

Specs: Rated for the load. 3-way controls from two locations; 4-way adds a third.

Tip:Switches the hot (black) leg only. Never switch the neutral.

Dimmer Switch

Control

Reduces light output; must match load type (incandescent, LED, CFL).

Specs: LED-rated dimmers required for dimmable LEDs. Check min/max wattage.

Tip:Mismatched dimmer/LED causes flicker and buzz. Some LEDs aren't dimmable at all.

Romex / NM Cable

Wiring

Non-metallic sheathed cable for indoor residential wiring.

Specs: 14 AWG (15A), 12 AWG (20A), 10 AWG (30A). White = neutral, black/red = hot, bare = ground.

Tip:Match wire gauge to breaker size. Don't bury junctions — all splices need an accessible box.

Conduit (EMT/Rigid)

Wiring

Metal or PVC tubing protecting wires, common in commercial work.

Specs: EMT, RMC, IMC, PVC. Fill limits apply per NEC chapter 9.

Tip:Required in commercial and exposed locations. Ground via the conduit or a separate equipment ground.

Transformer

Power

Steps voltage up or down for distribution and low-voltage loads.

Specs: Primary/secondary voltages and kVA rating. May hum faintly under load.

Tip:Loud hum, heat, or burning smell indicates a fault. De-energize before inspecting.

Dual-Run Capacitor

HVAC

Starts and runs the compressor and condenser fan. The #1 failed AC part.

Specs: Labeled like 45+5 MFD ±6% 440VAC. Three terminals: C (common), HERM, FAN.

Tip:Test with a multimeter on µF mode — within ±6% of label is good. Replace with the same µF, equal-or-higher voltage. Discharge before touching.

Contactor

HVAC

Heavy-duty relay that switches 240V to the compressor and fan when the 24V thermostat calls.

Specs: 1-pole or 2-pole, 30–40A contacts, 24V coil.

Tip:Pitted/welded contacts and insect nests are common. Cheap, easy swap — match pole count, amperage, and coil voltage.

Compressor

HVAC

The sealed pump that circulates refrigerant — the heart of the system.

Specs: Nameplate lists RLA (running amps) and LRA (startup surge). 208–230V in residential units.

Tip:Humming but not starting: try the run capacitor first. Repeated breaker trips at startup often mean a worn compressor. Sealed-system work requires EPA 608 certification.

Blower Motor / ECM Module

HVAC

Indoor fan that moves air across the evaporator coil and through the ducts.

Specs: PSC motors use a run capacitor (match µF); ECM motors use a replaceable control module.

Tip:Hum with no spin on a PSC = try the capacitor. ECM modules blink fault codes — note the code before replacing the module.

Condenser Fan Motor

HVAC

Outdoor fan that pulls air through the condenser coil to reject heat.

Specs: Commonly 1/6–1/4 HP, 208–230V, matched to the fan blade pitch.

Tip:Not spinning while the compressor runs = bad motor or the fan side of the dual-run capacitor. Test the FAN side of the cap first.

Condensate Float Switch

HVAC

Safety switch that kills the system when the drain pan fills to prevent water damage.

Specs: Normally closed; wired into the thermostat or 24V control circuit.

Tip:A 'dead' air handler with water in the pan is usually just this switch doing its job — clear the drain, then reset.

Outdoor Disconnect Box

HVAC

Local shutoff at the condenser — pull-out or switch type, some fused.

Specs: 240V, 30–60A rated to match the circuit.

Tip:Whip fuses inside blow before the panel breaker in many units. Check here first when a condenser is dead.