X - Y capacitor
An X2 capacitor is a safety-rated EMI suppression capacitor designed to be connected across the AC mains (Line–Neutral).
It is defined by IEC 60384-14 and used mainly for noise suppression and interference filtering in power supplies and AC equipment.
Where X2 capacitors are used
AC Line (L) ──||── AC Neutral (N)
↑
X2
Typical locations:
- Across L–N in SMPS input
- EMI filters
- Appliances, chargers, adapters
- Motor controllers
What “X2” specifically means
| Parameter | X2 Rating |
|---|---|
| Connection | Line ↔ Neutral |
| Rated AC voltage | ≤ 300 VAC (typically 275 VAC) |
| Surge voltage capability | 2.5 kV |
| Failure mode | Self-healing, non-flammable |
| Safety standard | IEC 60384-14 |
X-class vs Y-class (important)
- X capacitors → across L–N
- Y capacitors → from L/N to Earth (PE)
| Class | Location | Safety Risk | Typical Rating |
|---|---|---|---|
| X2 | L–N | Low | 275 VAC |
| X1 | L–N | Higher surge | 440 VAC |
| Y2 | L–PE / N–PE | High (shock risk) | 250 VAC |
| Y1 | L–PE / N–PE | Highest | 500 VAC |
- ⚠ Never replace a Y capacitor with an X capacitor
- ⚠ Never use a normal film capacitor in place of X2
Typical X2 capacitor characteristics
- Dielectric: Metallized polypropylene (MKP / CBB)
- Capacitance range: ~100 pF to 1 µF
- Flame-retardant epoxy case
- Certified marks: ENEC, VDE, UL, CQC