Strange: MacBook Air has a grounded power cord connected to an unearthed power brick

http://www.apple.com/shop/question/answers/mac/grounding-my-macbook-air/Q9CP2T4FKJ9HPU4JY

Do you happen to have any plausible explanation for this?

Maybe it's not the best forum to ask. But I thought you know a few things about electricity. Do you have a possible explanation?

I suspect that the 3 prong extension cable can also connect to other devices and some of them may actually be grounded?

I also suspect that the same power supply is used across the globe and the connected end for the wall is all that s different so the modularity that allows for this ends up with this difference.

Every one of the extensions from Apple that I have seen without the earth prong uses a different more oval connector on the power supply end where all of them that I have seen with the sliding connector on the power supply end have the 3rd prong aside from the 2 prong flip-up which lets you hang the supply directly on the outlet.

Why is this a deal for you anyway?

Those forum answers are evidently ill informed. Assuming the general design of all Macbook chargers are about the same, take a look at this teardown:

http://www.righto.com/2015/11/macbook-charger-teardown-surprising.html

and see note 12 near the end. I tested my own 2008 Macbook Pro charger and superficially agree - I measure 1kohms between AC ground and Magsafe ground (I didn't open my charger to check for the 9.1Mohm resistors) when using the grounded plug cable. My device has USA plugs.

I do not know the engineering reason for this, when they also supply the ungrounded "duckhead" 2 blade plug, which, I assume, also meets all safety regulations. My wild guess is that some countries may require this and not supply a 2 blade adapter. Or if someone in the USA complains about feeling leakage buzz on their device, they may recommend using the grounded cord.

The charger most definitely has a ground connection. It's the metal stud on the charger.

It could simply be a case of improved EMI with the ground connection or the ground holds the cord to the wall better. There are some countries that do require grounding.