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I'm doing a show in an exhibit hall and will be using my laptop with a credit card reader. I need to order my power connection and my choices are: 5 amps; 10 amps; 15 amps, or 20 amps (all at 110V).

I want to be able to take credit cards but don't want to get more power than necessary due to the cost. How can I figure out how many amps my laptop and credit card reader will require to operate?

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Most likely, all you will need is 5 amps. Look at your laptop power adapter (the black brick). On the backside it should tell you what the power draw is in amps. Most likely its 1 to 2 amps. The credit card reader should have a sticker on it as well on its bottom or its own power adapter. Note the amps it requires. Add up the total amps between the laptop and the credit card reader and you have the amount of power you need.

Here's an example - you'll want to check the input amperage (highlighted), not the output amperage.

Laptop power supply

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