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Old 07-13-2011, 08:49 PM   #1
Oct 2009
Princeton, NJ
Posts: 52
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I'm wondering if a switches amperage rating changes as the voltage on it changes.

For example, I have a switch rated at 660V and 10A. I'm wondering if this can handle switching a 240V 30A load (in lieu of a power relay for a 240V 5500W element).

Thanks for any help.

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Old 07-13-2011, 08:58 PM   #2
Mar 2010
Beer Capital of the World
Posts: 1,069
Liked 12 Times on 11 Posts

Yes, a switch's amp rating does change as the voltage changes, but we can't tell you exactly what the different ratings may be. Only the manufacturer can tell you. IMO, you shouldn't have that kind of current running through a switch. The switch should activate a relay that can handle the current.
"You can do anything you set your mind to when you have vision, determination, and an endless supply of beer."

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Old 07-13-2011, 10:30 PM   #3
Aug 2010
South Carolina
Posts: 9
Liked 1 Times on 1 Posts

The values provided for amps and voltage are maximums per the manufacturer. It is not uncommon for a switch to have a different rating at a lower voltage, but it should not be assumed. In most cases, if a switch has multiple ratings they will be listed on the switch, or in the manufacturer's documentation.

The thermal stress on a switch is a function of the amps no matter what voltage is applied, so there will be a limit to the amps any switch can carry. Opening and closing creates arcing and mechanical forces that can vary based on voltage and current, and type of load. Stay within the rated value(s) for the switch.

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