Are there any guidelines?

Do the guidelines differ depending on resistive/inductive/reactive loads?

For example, the Vishay VO2223A is rated up to 1A. At 110V it seems it can switch up to a 1 A x 110V = 110 watt load. I saw some training material that indicated only up 22W load. Is this derating for safety? Is it to cover startup current draws?

I'd like to independently switch several AC devices: 50W heater, 23W CFL, 4W water pump.

  • \$\begingroup\$ The Vishay VO2223A you gave a link to is not a solid state relay but a optically isolated triac... Is this a question about the vishay or solid state relays? \$\endgroup\$
    – Kit Scuzz
    Commented Nov 12, 2012 at 7:59
  • \$\begingroup\$ Thanks. I'd be interested in the answer to both, though if I had to pick one, I'd say Vishay. \$\endgroup\$
    – Brian Low
    Commented Nov 12, 2012 at 8:19
  • \$\begingroup\$ Could you perhaps describe what you're trying to do? The two questions aren't terribly related... solid-state relays and triacs aren't the same thing, so the answer to "both" questions is very different. \$\endgroup\$
    – Kit Scuzz
    Commented Nov 12, 2012 at 10:07
  • \$\begingroup\$ Edited question to provide more info. \$\endgroup\$
    – Brian Low
    Commented Nov 12, 2012 at 21:08
  • \$\begingroup\$ Is there any answer to this? I want to control a 60W light bulb, and 120V @ 0.9A would seem to allow this, but I too see the mention of it only being able to control 22W, which seems crazy, as then what's the point of it being able to control 0.9A? \$\endgroup\$
    – tic
    Commented Oct 3, 2016 at 19:14

1 Answer 1


It's a typical derating commonly used in various industries. Primarily to ensure long term reliability. And yes, that particular component can be referred to as a solid state relay.

  • 1
    \$\begingroup\$ What is a good guideline for derating? In this case max load = 25% of rated load? \$\endgroup\$
    – Brian Low
    Commented Nov 24, 2012 at 19:29
  • \$\begingroup\$ Is there any answer to this? I would like to use the VO2223A to control a 60W light bulb, which it seems it should be able to do, except for that 22W thing \$\endgroup\$
    – tic
    Commented Oct 3, 2016 at 19:15

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