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I have a power pack that is 12v 3a, I want to buy an inline switch so it can be turned off without having to unplug it. The following image is of the inline switch. It is rated for 24v at 2amp. If my understanding is correct, I can just multiply the V by the A and as long as it's lower than rated it's all ok.

Inline Switch: 24v x 2a = 48 watts DC Power Pack: 12v x 3a = 36 watts So it's ok to use.

Is this correct? Or am I mistaken and the switch shouldn't be used with this power pack?

DC Inline Switch

Layout

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    \$\begingroup\$ Simple answer is no since 3 A > 2 A, so you have violated the specification. In practice, you can somewhat trade voltage for current for a breaker but few manufacturers bothers to give their product multiple ratings. I would not heasitate one bit to use it as you intended for my own personal use. If in doubt, feel if it’s getting hot during use. Are you going to put it into production? \$\endgroup\$
    – winny
    Jun 8, 2018 at 20:36
  • \$\begingroup\$ Thanks for answering so quickly. I am plugging the power into a pretty expensive device. Would you risk $1000 on it? Sorry for bothering you further. Just want to see how big a risk I am taking. \$\endgroup\$
    – SystemX17
    Jun 8, 2018 at 20:39
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    \$\begingroup\$ Depends, do you have extremely long cable between the power supply and the device and very little to none input capacitance in the device? Then perhaps think twice. Also, was the DC connector pluggable and unpluggable by the user from the factory? If not and you have spliced in your breaker in series on the DC cable side, you may push the input stage to beyond what it’s tested for by the manufacturer. \$\endgroup\$
    – winny
    Jun 8, 2018 at 20:51
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    \$\begingroup\$ Then switching action should be zero problem, but I can’t tell if you are creating a ground loop by connecting it that way. Probably not but can you sketch a simple block diagram and I will be able to tell? \$\endgroup\$
    – winny
    Jun 8, 2018 at 20:54
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    \$\begingroup\$ Good! I forsee no issue. \$\endgroup\$
    – winny
    Jun 8, 2018 at 21:55

2 Answers 2

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Simple answer is no since 3 A > 2 A, so you have violated the specification.

In practice, you can somewhat trade voltage for current for a breaker but few manufacturers bothers to give their product multiple ratings. I would not heasitate one bit to use it as you intended for my own personal use. If in doubt, feel if it’s getting hot during use. To use it in mass production is another thing where you need to stay within such ratings.

Here is an example from the internet about switches in general. As the voltage goes up, the current rating drops and vice versa. enter image description here

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Since the voltage rating of the switch is higher than the supply, it is NOT a problem. However, since the supply CAN provide 3A, if the load draws this amount, the switch will get hot and may malfunction. But even if the switch "malfunctions," the load most likely will not be damaged.

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