Ceramic box · 22 × 10 × 9 mmEnd filler (cement)5W 10ΩJ (J = 5%)Pins

White rectangular ceramic box, value and power on front, two axial pins
Varies with power; the 5 W type is about 2 cm long

Resistors

Cement (power) resistor

In simple terms

What is this?

A powerful resistor embedded in a white ceramic case; a sturdy pipe that turns excess flow into heat.

What is it for?

Turns a few watts of power into heat; used for discharging batteries and capacitors and for loading.

Where do you see it?

In power supplies and amplifiers: big white rectangular parts.

How do you spot it?

A white rectangular ceramic case and two pins; the value and power are printed on it in plain text.

Caution:

It gets very hot; do not stick it to the board, leave an air gap under it and do not touch it.

Technical definition

A power resistor sealed with cement-like filler in a white ceramic box. It usually has a wirewound or metal-oxide element. Its value and power are printed on the body.

Power2–20 W

Tolerance±5%

Schematic symbol IEC and ANSI differ

IEC 60617: the drawing style used in Türkiye and Europe.

Pins 2

1Pin 1Has no direction1

2Pin 2Has no direction2

Features typical

Power: 2 · 3 · 5 · 10 · 20 W
Tolerance: ±5% (J)
Internal structure: Wire-wound or metal oxide
Marking: Plain text, e.g. “5W 10Ω J”
Surface temperature: Gets very hot at full power
Example part: SQP series 5 W

Common mistakes

Mounting flush against the boardBecause the body gets hot, solder it a few mm above the board; this keeps the board from darkening and lets air circulate.

Choosing power right at the limitPick a resistor rated at least twice the power you calculated. A resistor running at its limit gets very hot.

Test with a multimeter

Test whether this part is good with the multimeter on the measurement screen.

Take a measurement

Where it is used

Battery discharge testCapacitor dischargePreload on a power supplyInrush current limiting