centiampere

A centiampere (cA) is a unit of electric current equal to 0.01 amperes or 10 milliamperes. It sits between the milliampere and the ampere in the decimal hierarchy of SI current units. In practice, this scale covers moderate currents: the output of a small battery charger, a heating element in a precision instrument, or a solenoid coil in industrial control gear.

The centiampere emerges most often in inspection and test work where current must be measured with reasonable precision but without the finer resolution that milliamperes demand. A digital multimeter set to a 200 cA range will read currents from roughly 0.01 to 2 amperes with good accuracy. Similarly, older analog test instruments and mechanical ammeters frequently featured centiampere scales as a practical midpoint between coarse and fine measurement.

Where it appears in industry

Centiampere ratings appear in control circuits, pilot lights, solenoid coils, and low-power sensor circuits. A relay coil might draw 50 to 150 cA at rated voltage. Test specifications for electronic assemblies often cite acceptable current draw in centiamperes. Industrial safety standards may specify maximum leakage currents to ground in this range. The unit is also common in laboratory settings, where precision low-current sources and measurement instruments are calibrated in centiampere increments.

The term itself follows the standard metric prefix convention: centi-, meaning one-hundredth, applied to the ampere. Unlike milliamperes or microamperes, which dominate modern practice due to the prevalence of low-voltage electronics, the centiampere has become less frequent in everyday use. It survives chiefly in older instruments, in certain control and safety specifications, and in metrological contexts where measurement ranges happen to fall naturally at that scale.