Macabook Pro and Earthing

anpaman

macrumors regular
Original poster
Feb 13, 2018
111
11
Hi all

I have MacBook Pro and the power adapter has 3 plug like this.

https://www.amazon.co.uk/Duckhead-Adapter-Apple-Macbooks-iPhone

But it was not earthing during charging and I could feel buzzing sensation as you touch the metal of MacBook Pro.
People said it could fix it by using power adapter extension cable. Appe store in here sold version has 3 plug.

https://www.apple.com/sg/shop/product/MK122B/A/power-adapter-extension-cable

I heard some peoples experienced the buzzing caused they have use power adapter has 2 plug but fix it by used extension cable has 3 plug.

My power adapter already has 3 plug but still buzzing. Would the extension cable fix it ?

Thank
 

Chancha

macrumors 6502a
Mar 19, 2014
920
793
The AC adaptor itself (sans the plug) has 3 contacts, 2 are inside the figure-8 hole are live + neutral, where the exposed metallic disc is the ground. Many people including you are not ware of it being the ground contact since it looks only functioning as a hook for the adapted plug / cord.

When you insert a direct plug onto the adaptor, notice the rails are plastic, so you will never get a ground despite the plug may have a 3rd prong.

If you pay attention, the inside of the rail of an extension cord has extra metallic springs underside, which are wired to a ground wire, which of course goes all the way to the 3rd prong of the other end of the cord.

As far as I know, the only reason of the difference between a plug and a cord has to do with some electricity safety law, because the 110/220v or whatever socket voltage is not yet transformed to much less harmful lower voltage until the power reaches the adaptor brick, therefore the cord and both its ends are deemed dangerous if ungrounded. With a direct plug config this risk is eliminated / minimized.

RtHLq.jpg
GGqwH.jpg
 

anpaman

macrumors regular
Original poster
Feb 13, 2018
111
11
The AC adaptor itself (sans the plug) has 3 contacts, 2 are inside the figure-8 hole are live + neutral, where the exposed metallic disc is the ground. Many people including you are not ware of it being the ground contact since it looks only functioning as a hook for the adapted plug / cord.

When you insert a direct plug onto the adaptor, notice the rails are plastic, so you will never get a ground despite the plug may have a 3rd prong.

If you pay attention, the inside of the rail of an extension cord has extra metallic springs underside, which are wired to a ground wire, which of course goes all the way to the 3rd prong of the other end of the cord.

As far as I know, the only reason of the difference between a plug and a cord has to do with some electricity safety law, because the 110/220v or whatever socket voltage is not yet transformed to much less harmful lower voltage until the power reaches the adaptor brick, therefore the cord and both its ends are deemed dangerous if ungrounded. With a direct plug config this risk is eliminated / minimized.

Does all of apple extension cord has extra metallic springs underside ?
 

Chancha

macrumors 6502a
Mar 19, 2014
920
793
Does all of apple extension cord has extra metallic springs underside ?
I think so, as long as it's Apple originated then it has to be grounded, unless the cord is localized for specific regions where their wall sockets don't even have ground.

Btw some people use a short wire to achieve grounding. Not sure how safe it is though.

TWkOg.jpg
 

_Kiki_

macrumors 6502a
Aug 13, 2017
844
253
I think so, as long as it's Apple originated then it has to be grounded, unless the cord is localized for specific regions where their wall sockets don't even have ground.

Btw some people use a short wire to achieve grounding. Not sure how safe it is though.

View attachment 827677
Apple screwed up simple thing like ground, this is stupid