![]() However, I understand that Apple is no longer shipping the three prong extension cable with some machines, which is bizarre and churlish, but there it is. Mac laptops have historically been shipped with both an ungrounded two prong plug and a grounded three prong extension cable for the power adapter, and “the tingle” was something that was usually resolved by using the grounded (three prong) extension cable with the power adapter. The solution for eliminating micro-vibration of MacBooks Verifying that the leakage current is a safe level is part of the certification testing for the power adapter. In order to reduce the amount of EMI, there exists a tiny amount of leakage current through the filter capacitor. So what it boils down to is a design trade off between leakage current and EMI noise suppression. This is not enough to be dangerous, most people can’t even feel it, but it can cause slight tingling in certain circumstances, especially if you body has a good connection to earth ground. This electrical grounding effect is more or less also impacted by the country standard voltage and your personal office set up (wearing shoes, having a carpet or not…).ĭepending on the design standard, this leakage current is limited to two or three hundred microamps. This means it is an permanent problem of all MacBooks, MacBook Airs and MacBook Pros. Some of them thought that it’s “normal” for MacBooks! Somebody told me that his 12 year old MacBook Pro got this electrical issue, too. I asked a lot of my Apple friends and all (!) reported these micro-vibrations. Other laptops with a plastic case usually don’t have the problem. This is particularly common complaint for MacBooks because of their metal case. ![]() That means there is no direct electrical connection between the AC outlet ground and the laptop chassis ground. They are completely isolated from each other by isolated power inductors operating like an isolation transformer. There is no direct electrical connection between the power mains and the low voltage laptop side of the adapter. This is a normal consequence of how the power adapter is designed. The power adapters does not have an additional electrical grounding line, hence it feels in your fingers as the MacBook vibrates if touched while charging. This ‘micro-vibrations’ are generated due to a lack of sufficient electrical grounding of the MacBook. The origin of the micro-vibration of MacBooks Some users find it alarming or inconvenient. The ‘vibration’ as some call it, or ‘tingling sensation in the fingers’ or ‘Macbook vibrates if touched” as other call it (while charging) is not harmful to your Mac or to you. ![]() MacBook_Pro_Fixing Vibrations While Charging No Grounding
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