450V Capacitor: Motor & HVAC Specifications Complete Guide

If you’ve ever pulled apart a failed air conditioner compressor unit or debugged a single-phase motor that refuses to start, chances are high that a capacitor is your culprit. Specifically, a 450V capacitor — the workhorse voltage rating for AC motor run and start applications across HVAC systems, water pumps, washing machines, and industrial fans.

The 450V AC rating isn’t arbitrary. Most single-phase AC motors in domestic and light-industrial applications run on supply voltages between 220V and 240V (50Hz) or 230V to 277V (60Hz). The peak voltage on a 240V AC supply is around 340V. The 450V rating provides a meaningful safety margin above these transient peaks, and the voltage range for motor capacitors typically runs from 250VAC to 450VAC for start-up applications. InspectApedia Choosing 450V means you’re not riding the edge of the component’s limits during every switching transient.

This guide is written from a hands-on PCB and power electronics perspective. We’re going to cover the CBB series capacitor families you’ll encounter in real field work, walk through selection criteria, and give you a practical reference for replacement and troubleshooting.

Understanding the CBB Series: The 450V Capacitor Families

When you search for a 450V capacitor for a motor or HVAC application, you’ll quickly run into CBB60, CBB61, and CBB65 part numbers. These designations aren’t brand names — they’re Chinese national standard codes for polypropylene film motor capacitors. Here’s what each code actually means:

The prefix “CBB” breaks down as: C = Capacitor, B = non-polar organic film dielectric, B = polypropylene specifically. The number suffix indicates the mechanical and application category. CBB60 refers to a plastic can motor run capacitor (JFS standard), CBB61 refers to a motor running capacitor in a box format, and CBB65 refers to a motor running capacitor with an aluminum shell filled with castor oil or wax under vacuum. Kscapacitor

CBB60: The Pump and Compressor Workhorse

The CBB60 capacitor is a crucial component in single-phase AC motor circuits, primarily functioning as a run capacitor. Its design leverages a metallized polypropylene film dielectric, which offers high insulation resistance, low losses, and robust self-healing properties. AnyPCBA

You’ll find CBB60s in cylindrical plastic housings, filled with epoxy resin for sealing. CBB60 and CBB65 capacitors’ operating voltage is about 450VAC, and they’re used as AC motor run capacitors for phase change, mainly in air conditioners, washing machines, and water pumps. Kscapacitor In terms of capacitance, CBB60s typically span from 1µF up to about 100µF at 450VAC for higher-power pump applications.

CBB61: Fan and Low-Power Motor Applications

The CBB61 uses the same metallized polypropylene film construction as the CBB60, but it comes in a rectangular box-shaped plastic casing rather than a cylinder. The CBB61 capacitor is widely used for ceiling fans, wall fans, stand fans, industrial fans, range hood fans, air exchange fans, water pumps, motors, and generators. Lowe’s Its rated voltage sits at 450V AC with typical capacitance values ranging from 1µF to 30µF, and it’s rated for 50/60Hz operation.

The box form factor makes CBB61 easier to mount in flat panel spaces — something you’ll appreciate when you’re trying to fit a replacement into a ceiling fan canopy with almost no clearance.

CBB65: The HVAC Heavy-Duty Choice

CBB65 capacitors are designed for higher voltage and frequency applications such as HVAC systems, with a more robust design and better heat handling capabilities for demanding environments compared to CBB60. AnyPCBA The key difference in construction: CBB65 capacitors are filled with refined castor oil and wax under vacuum impregnation, improving capacitor insulation, while CBB60 and CBB61 use epoxy resin filler. Kscapacitor

The CBB65 uses an aluminum shell rather than plastic, which gives it better heat dissipation — critical in a compressor compartment where ambient temperatures regularly exceed 60°C. This is why you’ll see CBB65s specified for air conditioner compressor motors almost exclusively.

450V Capacitor Specifications: The Numbers You Need to Know

When specifying or replacing a 450V capacitor, the label markings tell you everything — if you know how to read them. Here’s the full breakdown:

Key Electrical Parameters

Parameter	Typical Value	Notes
Rated Voltage	450V AC	Peak AC voltage the cap can handle continuously
Capacitance Range	1µF – 100µF	Varies significantly by motor size
Capacitance Tolerance	±5% (run), ±10–20% (start)	Tighter for run caps
Dissipation Factor (tan δ)	≤0.004 at 100Hz	Lower = less heat, better efficiency
Insulation Resistance	≥3000 MΩ·µF	High IR means low leakage
Frequency	50/60 Hz	Most are dual-rated
Operating Temperature	-40°C to +70°C (CBB60/61)	CBB65 often rated to +85°C
Operating Life	60,000 hours typical	At rated temperature

Physical Specifications by Series

Series	Shell Material	Filler	Typical Shape	Primary Use
CBB60	Plastic (ABS/PP)	Epoxy resin	Cylinder	Pumps, washing machines, compressors
CBB61	Plastic (ABS)	Epoxy resin	Rectangular box	Fans, light-duty motors
CBB65	Aluminum	Castor oil/wax (vacuum)	Round cylinder	HVAC compressors, heat pumps
CD60	Plastic	Asphalt	Cylinder	Start-only (intermittent)

Motor Start vs. Motor Run: Getting This Wrong Will Kill Your Motor

This is the mistake that causes the most confusion in the field, so let’s be direct about it.

A run capacitor stays in circuit continuously while the motor is operating. It maintains the phase shift needed for efficient torque generation and smooth running. Run capacitors use metallized polypropylene film — rated for continuous AC duty — and typically have lower capacitance values (1.5µF to 60µF at 450V).

A start capacitor is only in circuit for the first 0.5 to 3 seconds of motor startup to boost starting torque. It’s then switched out by a centrifugal switch or PTC thermistor. Start capacitors possess very large capacitance values for their size and voltage rating and are only intended for intermittent duty. For this reason, start capacitors will fail after being left energized for too long due to a faulty starting circuit on a motor. A start capacitor can never be used as a run capacitor because it cannot handle current continuously. TEMCo Industrial

Start capacitors typically range from 20–30 µF up to 250–300 µF. InspectApedia If you see a cylindrical capacitor with a 450VAC rating and a value over 80µF, it’s almost certainly a start cap (often CD60 series) — and it will fail quickly if left in a run circuit.

HVAC Applications: Where 450V Capacitors Are Most Critical

Air Conditioning Compressor Motors

The compressor is the heart of any refrigeration cycle, and it’s where capacitor failures cause the most expensive damage. Most residential and light-commercial HVAC compressors use single-phase induction motors requiring a run capacitor in the 20–60µF range at 450VAC. When the run cap weakens, the motor draws more current trying to compensate, which overheats the windings.

A dual run capacitor combines both the compressor run capacitor and the condenser fan motor run capacitor in a single hermetically sealed unit. Most run capacitors are rated for 2.5–100µF with voltage ratings of 370 or 440VAC, and are usually 50/60Hz rated with round or oval case designs using either a steel or aluminum shell. TEMCo Industrial In replacement work, a 450VAC unit is fully compatible as a direct upgrade over a 370V or 440V rated unit.

Fan Motors, Pumps, and Ventilation Systems

CBB series 450V capacitors excel in HVAC systems, with other common applications including electric motors, industrial power supplies, and high-voltage amplifiers. Alibaba For fan motors specifically, the CBB61 in box form is standard on ceiling fans and exhaust systems, while CBB60 cylindrical types are used in condenser fan motors and blower assemblies.

In pump applications — pool pumps, pressure boosters, sump pumps — CBB60 capacitors rated at 450VAC are almost universal for single-phase motors up to about 3HP. The higher voltage rating matters here because pump motors often experience voltage transients from long cable runs.

How to Select and Replace a 450V Capacitor Correctly

Selection Checklist

Getting a replacement wrong doesn’t just mean the motor won’t start — an oversized start cap can keep the start winding energized too long and burn it out. When replacing an electric motor capacitor, never put in a lower rated capacitor. If you cannot find an exact size match, it is acceptable to use a capacitor rated one step higher in µF. InspectApedia

Use this checklist every time:

Parameter	What to Do
Voltage rating	Match or exceed (450V replaces 370V, 400V, 440V)
Capacitance (µF/MFD)	Match exactly; ±5–10% tolerance acceptable for run caps
Frequency	Must match (50Hz or 60Hz; most are dual-rated 50/60Hz)
Start vs. Run	Never swap — confirm with original part number
Terminal count	Match exactly (run caps typically have 3–4 terminals per post)
Physical dimensions	Must fit the mounting bracket and enclosure
Temperature rating	Match or exceed original; CBB65 to +85°C for compressor locations

Reading the Capacitor Label

A typical 450V capacitor label might read: CBB60 — 25µF ± 5% — 450VAC — 50/60Hz — 40/70/21

That last code (40/70/21) is the climatic category per IEC 60068: lower operating temperature limit is -40°C, upper is +70°C, and 21 days of damp heat testing. If your application has higher ambient temperatures, make sure the upper limit is +85°C or above.

Standards and Certifications to Look For

For HVAC and motor capacitor applications, compliance markings aren’t optional — they matter both for safety and for insurance/warranty purposes. Capacitors like those from Ducati Energia and TDK engineered for EN60252-1 compliance offer a capacitance range of 1.5 to 45µF and voltage ratings up to 470V, designed for motor run applications with self-healing capabilities. Sourcify China

Key standards for 450V motor capacitors:

IEC 60252-1 — The main international standard for AC motor capacitors. Covers motor run and motor start types, safety requirements, and test methods.

UL 810 — The US standard for capacitors used in equipment connected to power mains. Required for UL-listed HVAC equipment sold in North America.

EN 60252-1 — European equivalent of IEC 60252-1, required for CE marking.

GB/T 3667 — Chinese national standard governing CBB-series motor capacitors. Relevant when sourcing from Chinese manufacturers.

Useful Resources for Engineers and Technicians

Standards and Technical Documents

• IEC 60252-1 — AC Motor Capacitors standard: webstore.iec.ch
• UL 810 — Capacitor safety standard: ul.com/standards

Manufacturer Datasheets and Technical References

• JB Capacitors CBB60 Datasheet (includes full dimensional chart for 250V and 450V): jbcapacitors.com
• ASC Capacitors X349 Series — 450V HVAC/refrigeration film capacitors: ascapacitor.com
• TemcoIndustrial Motor Capacitor FAQ — Practical replacement guidance: temcoindustrial.com
• KS Capacitor CBB Series Guide — CBB60/61/65 comparison: kscapacitor.com

Component Databases and Selection Tools

• Digi-Key 450VAC Capacitor Selector — Filter by voltage, capacitance, series: digikey.com
• Mouser Motor Capacitor Parametric Search: mouser.com
• GlobalSpec Capacitor Selection Guide: globalspec.com
• KEMET SpiCap Tool — Capacitor simulation: ksim3.kemet.com

Frequently Asked Questions About 450V Capacitors

Can I replace a 370V or 440V capacitor with a 450V capacitor?

Yes, and in most cases this is actually the preferred approach. The voltage rating on a motor capacitor indicates the maximum continuous AC voltage the component can handle safely — a higher rating simply means more margin. A capacitor will have a marked voltage indicating its acceptable peak voltage, and you can select a capacitor with a voltage rating at or above the original capacitor. TEMCo Industrial Replacing a 370VAC unit with a 450VAC equivalent of the same capacitance is fine electrically. Just verify the physical dimensions and terminal configuration match.

Why does my 450V HVAC capacitor keep failing?

The most common causes are prolonged operation above the rated temperature (compressor compartments in hot climates regularly exceed 60°C), overvoltage from the utility supply, or a failing motor that draws excessive current and stress-cycles the capacitor repeatedly. Also worth checking: if someone previously installed an undersized replacement, the capacitor has been running at or above its rated limits. Always match the original capacitance value closely. An oversized start capacitor can prevent the centrifugal switch from opening, leaving a start cap in circuit during run — which kills it quickly.

What does MFD mean on a capacitor label?

MFD stands for MicroFarad — it’s the same as µF, just an older labeling convention still common on HVAC replacement parts. So a capacitor labeled “25 MFD 450V” is a 25µF 450VAC capacitor. You’ll see both notations used interchangeably on replacement caps, especially in the North American HVAC market.

Is a 450V capacitor AC-rated or DC-rated?

Motor and HVAC capacitors are rated for AC voltage, which is fundamentally different from DC ratings. A 450VAC-rated capacitor is built to handle the full sinusoidal AC waveform continuously, including reverse-polarity half-cycles. You cannot substitute a DC-rated capacitor of the same voltage in an AC motor circuit — DC electrolytic capacitors are polarized and will fail destructively on AC supply. Always verify the “VAC” suffix on any motor capacitor replacement.

How do I know if my 450V motor capacitor has failed?

The most reliable test is with a capacitance meter set to the appropriate µF range — a failed run cap will read significantly below its rated value (more than 10% low is cause for replacement), while a shorted cap will read near zero and may show the case bulging or a blown safety vent on top. Symptom-wise: a motor that hums but won’t start, runs hot, trips its thermal overload repeatedly, or a compressor that starts slowly and draws high amperage are all classic indicators of a weak or failed run capacitor. A capacitor with a visibly swollen case or discoloration should be replaced immediately regardless of the meter reading.