I have seen a few posts about using capacitors to filter the mains. If you are doing this you need to use either Class X or Class Y Safety rated capacitors. So what do these safety ratings mean.
For Your Information:
Class X capacitors are for use where there is NO danger of electrical shock in the event of capacitor break down. That is for use across Active and Neutral where a failure may cause a fuse to blow but will not result in the case becoming live.
Class X is divided into 3 sub groups according to the peak (impulse) voltage to which they are exposed IN ADDITION to the line voltage.
X1 for 2.5kV < Vpk <= 4kV
X2 for Vpk <= 2.5kV
X3 for Vpk < 1.2kV
In general you should always use Class X1 or X2 for Active to Neutral Suppression Caps
Class Y capacitors are used where there IS A DANGER of electrical shock in the event of a capacitor break down. That is for use from Active or Neutral to Earth where failure of the capacitor may result in LIVE parts.
Class Y is divided into 4 sub groups acording to voltage rating AND Class of Insulation of the Equipment
Y1 for DOUBLE (or Reinforced) INSULATED equipment to 250 V (Tested to 8kV Vpk)
Y2 for ordinary equipment between 150 and 250V (Tested to 5kV Vpk)
Y3 as for Y2 BUT no additional peak voltage test requirement
Y4 for ortdinary equipment up to 150V (Tested to 2.5kV Vpk)
In general you should always use Class Y2 for Active or Neutral to Earth Suppression Caps
Hope some of you have learned something - appologies to those "experts" who already knew all this.
Cheers,
Ginger
