Why are some power adapters center positive and others center negative (less common, at least around me)?

Is there any compelling reason, something that asks for one or the other for different devices? Couldn't they all be center positive as a matter of convention?

Is this like asking why not all cars drive on the left (right) side of the road? Or why not all countries use the metric system?

  • \$\begingroup\$ One reason for having a center-positive connector is that it is much more difficult to inadvertently short the positive to a grounded metal object, since it is recessed a little bit. \$\endgroup\$ – Tyler Stone Jun 18 '19 at 20:18

Some manufacturers decide to make their power supply "unique" to them and to that end, they also use different sizes or types.

The Apple magnetic series (magsafe) is a good example, while they use multiple terminals to identify the type of battery capacity and the correct charge rate, it is unique to Apple.

Much the same as the mains plugs - every country thinks that theirs is the "best" system... UK has 3 pin, but the EU uses either two or 3 pin, both of which fit in the same socket.


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