I have an old fan which is controlled by a switched potentiometer (see photo). Unfortunately it's become faulty so I need to replace it. It has five pins - I gather two of them are for the switching part.

On the case it says "250V 1A" and also "220K". The 220K must be its resistance and the 250V the max. voltage. However, is the 1A really a current rating or some other mark/value? It seems a bit high as that'd be 250 W.

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1 Answer 1


250 V, 1 A, is the rating of the on-off switch (and that will be for AC). The 250 W will be dissipated in the load, not in the switch. The switch contact resistance should be very low - maybe half an ohm which would give a power dissipation in the switch of 0.5 W at 1 A. That would be fine.

The potentiometer is 220 kΩ.

  • 1
    \$\begingroup\$ As often as not, this kind of switch can be rejuvenated by dismantling and careful cleaning (provided nothing is 'broken') Your mileage may vary \$\endgroup\$
    – Kyle B
    Commented Sep 13, 2022 at 3:00

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