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Start Cap

Start Cap Troubleshooting

Start capacitors are commonly used in motors in both residential and light industrial applications. They are found in band saws, grinders, pool and spa pumps, air compressors, table saws, and much more. Often, when one of those motors fails to start, the problem may lie within the start capacitor. We'll show you some simple diagnostics you can do to see what went wrong.

Replacing a Start Cap in a Single Phase Motor

Learn how to replace a start cap in a single phase motor.

Bleed-Down Resistor Installation

Learn how to install a bleed-down resistor onto your start capacitor and why it's important.

Is it time to replace your Electric Motor's Start Cap?

Depending on the frequency of starting of a piece of machinery, the relative load during start-up and the temperature of environment that it is operated in, every motor's start capacitor will eventually have to be replaced. How do you know if your start cap is bad? Most electric motor start capacitor failures are one of two types

"The Start Cap blew its guts out!" This is what we call catastrophic failure. It is usually caused by an electric motor's starting circuit being engaged too long for the intermittent duty rating of a start cap. The top of the start cap has literally been blown off, and the insides have been partially or fully ejected.

Similarly but not quite as dramatic, a start cap may just exhibit a ruptured pressure relief blister. In either case, it’s easy to tell that the start cap is in need of replacement.

Blown Start Cap
Start Cap Ruptured Blister

My motor is slow to start. Is my start cap bad?"

The answer to this question is maybe. Your start cap may have lost its capacitance rating due to wear and age, or you may have other non capacitor related issues related to other motor components.

Learn how to test a capacitor ».

What's the difference between a run cap and a start cap?

View our video below for an explaination of start vs. run capacitors and why start caps fail if used as a run capacitor.

Start Cap Special Volume Discount
Start Cap Shipping

Start Cap Help