How important is laptop earth

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Rikkitic

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#175161 19-Jun-2015 15:50

I have a laptop from America with external psu and 3-prong earthed power cord. I have NZ power cords from older laptops that could be made to fit the psu, but they are not earthed. This makes me wonder just how important the earth connection is on these devices. I know it matters for most things but many older laptops were never earthed so what are the consequences of not doing so?

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trig42

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#1327910 19-Jun-2015 16:18

It should be pretty easy to find an earthed NZ Plug Clover Leaf power cord (which is what most laptops use).

Does yours have a different socket in the power brick?

Rikkitic

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#1327920 19-Jun-2015 16:32

No that's what it is. But why buy something you already have if it doesn't make an important difference? Hence my question. If no earth was ok in the past, why not today?

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mattwnz

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#1327923 19-Jun-2015 16:42

The earth is for the PS, and not the laptop isn't it? The power coming from the PS into the laptop is low voltage DC power with a two pin connector, so isn't earthed, at least it is on the ones I have owned. Is the output exactly the same? I suspect the older PS with the older forms of transformers needed to be earthed

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#1327925 19-Jun-2015 16:43

It depends on the design of the AC Adapter.

Jase2985

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#1327926 19-Jun-2015 16:45

pretty sure you are right on that one.

pretty sure its earthed because the power supply isnt double insulated

richms

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#1327998 19-Jun-2015 18:27

There should not be a non earthed cable with a 3 pin cloverleaf on the other end of it.

If you have one, it is not standards compliant and should be thrown out. Same as all those crap IEC cables that have wire smaller than 1mm in them that come with lots of external drive enclosures etc. Importer would not have a SDOC for them anyway.

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#1328005 19-Jun-2015 18:55

If you don't want to buy the right cord. Just cut off the USA plug and wire on a nz one. The earth pin will be used for radio frequency suppression. If the laptop is a touch screen model you will probably have issues with using the touch screen. If you don't connect the earth.

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#1328056 19-Jun-2015 19:32

There are subtle reason why the power supply is earthed. If it is designed for no earth (like phone chargers), then there will be Y-capacitors (specific type of safety rated capacitors) from the output to main neutral. Larger power adapters usually have an earth connection, and then the Y-capacitor will be from output to earth. This capacitor needs to be connected to something, you need an earth connection.

BTW in China the phase and neutral of a kettle plug is reversed from the Western world. Very bad for compliance of non-earthed products when the Y-capacitor goes to phase instead of neutral.

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Rikkitic

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#1328132 19-Jun-2015 22:41

OK thanks for the info everyone. That is what I wanted to know. I don't have a problem putting a new plug on or buying a new cord, but if I already have something that will work and there is no downside to using it then why not? However now that I know what the earth does I will do it properly. Thanks again.

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richms

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#1328160 20-Jun-2015 02:14

China is wired the same in theory. It's Argentina that is reversed.

However in china polarity is a bit of a "meh" thing with lots of places just using 2 red or yellow wires for the AC and the earth is nowhere to be found. But slap a 2 and 3 pin socket on it. The hotel I stayed at had 2 separate wires coming out of the wall socket and over to the desk to a power outlet. But they had a red and a yellow so they may have had polarity correct.

Also in china green is the other phase colour. Bet that's caught a few imegrents out.

Richard rich.ms