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I recently bought a minivan that has 110V power outlets. I'd like to use my laptop in the van sometimes (not as the driver, of course), but my laptop has a three prong grounded plug, and the outlet is two prong.

What problems might I experience if I use a cheater plug (three prong to two prong adapter)? Why does a laptop need earth ground?

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  • Fast forward to 2017. I'm having this same issue. I have a laptop that has three prongs, obviously two for the current exchange, and the bottom pin for grounding. I have a particularly acute phobia with electrical appliances, and plugging things in, and out of sockets because I've been electrocuted when I was younger. I'm not entirely certain nor' am I willing to flip my plug upside down, or surgically remove the grounding from the power-cord... but as far as I've researched on many sites, and communities.. it seems to appear safe.
    – Jen
    Commented Mar 15, 2017 at 18:25

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You wouldn't experience any problems except in the rare case that your laptop has an internal short from a live power line conductor to an exposed metal part of the laptop.

The ground plug is purely for safety and has no effect on the proper operation of an electrical appliance. It accomplishes two things. First, it assures that the plug is inserted with the proper orientation so that the hot wire of the socket is connected in a predictable way to the appliance. Second, the safety ground wire is typically used in appliances that have a conductive case and the case is connected to the safety ground. If a short circuit were to occur inside the appliance, any current will be passed through ground, rather than through the body of someone who touches the conductive case.

The laptop will work just fine if the ground plug is removed or if the hot wire and neutral wire are reversed.

To answer the title of you're question, you may not want to remove the grounding pin because "If the customer alters the product in any way, then all warantees are void. It is, by definition, the customer's fault, whether there are technical reasons or not."

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    Assuming that this three wire cord plugs into an external power brick with no exposed metal pieces, you shouldn't have any problems.
    – Fiasco Labs
    Commented Nov 25, 2011 at 17:27
  • The appliance itself doesn't care which conductor is hot. The "neutral" is properly called the "grounded conductor." Both the hot and neutral carry the same amount of current while the device is in operation, and because the power source is AC, the direction of the current is changing either 50 or 60 times per second (depending on what part of the world you're in). What can be an issue is if you have a single throw switch on your device and you end up breaking the neutral, because the "hot" conductor will still feed energy into the device with the switch off, creating a shock hazard.
    – Craig Tullis
    Commented Dec 11, 2016 at 5:09
  • The ground prong has absolutely nothing to do with the case where the laptop is "trying to draw too much power", as claimed in your first paragraph. Your second paragraph, though, is correct. I am editing the answer accordingly.
    – Jamie Hanrahan
    Commented Feb 28, 2019 at 8:19
  • @Craig Some appliances DO care which conductor is "hot". Particularly devices that handle audio on unbalanced connections (i.e. the vast majority of consumer audio devices - including laptops).
    – Jamie Hanrahan
    Commented Feb 28, 2019 at 8:23
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As long as you aren't using a microphone, there is no issue.

But if you are, you will likely get mains hum while plugged in if you don't have a ground.

Laptops that only have 2 prong power adapters often also suffer from mains hum on the microphone jack or a usb mic. when plugged into mains. only the built in mic next to the webcam will be hum free because of how it's isolated.

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Your laptop might have a "tingly" sensation coming from a tiny current that runs trough the metallic parts of its case. This is normally solved by plugging it in "backwards".

If your heart is sane and your fingers are dry, this will not be more than a minor annoyance. There are entire countries that do not have grounding...

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  • Is Thailand one of those countries? thelocal.se/32990/20110404/#
    – Aki
    Commented Nov 25, 2011 at 15:12
  • Yes, it is. But there is an abysmal difference between water running through an ungrounded 220 V electric coil and not grounding a 12 V - 24 V laptop. I live in Paraguay. My shower is grounded. The rest of the house is not...
    – Dennis
    Commented Nov 25, 2011 at 15:25
  • My old laptop does that, and I live in a country with three-pin plugs and grounding ....
    – Alan B
    Commented Nov 25, 2011 at 17:04
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    @Dennis and for a good reason too. I have a friend that lived in Peru for a while. His story about the near death experience by shower and his wife trying to figure out how to pull his spasming body out of the shower stall was not something I'd like to experience.
    – Fiasco Labs
    Commented Nov 25, 2011 at 17:24
  • Downvoting for safety reasons.
    – MountainMan
    Commented Mar 15, 2017 at 19:24

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