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AC/DC voltage rating on Spit toggle switches [Washington, USA]

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RiPe Richard Peetz
Sequim, WA, USA   USA
Hey All,
I needed to replace a toggle switch on my Spit, so went to an auto parts store which had switches (common auto electrical part company) almost identical to the original Spit switches. The package said a rating of 12V at 15amps. Great. Upon getting home and opening the package, the markings on the switch said 3 amps at 250 volts AC. In my youth, many,many moons ago, I dabbled in electronics and back then the dogma was that one didn't mix AC and DC switches. Something to do with the composition of the contacts inside the switch, the DC contacts being engineered for current running in one direction only whilst the AC contacts were engineered for current running back and forth only. Not a question of wattage. Are new switches AC/DC? Any electrical engineers out there who can speak to this?

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spits paul krause
Sunnyandhot, FL, USA   USA
1968 Triumph Spitfire MkIII
1969 Triumph Spitfire MkIII "Rusty; Gone But Not Forgotten!"
1969 Triumph Spitfire MkIII
Switches can be used for either AC or DC but the current rating will be much lower for DC at a given voltage. That's due to the constant current at DC and the arcing that occurs when the contacts are broken.
You need to know what you need from the DC switch and evaluate the specs. For example, if you need to switch 10 amps DC you'll need a switch with a hefty rating if it's only cited for AC.



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