🚀 go-pugleaf

"Whiskers" <catwheezel@operamail.com> wrote in message 
news:slrnghbj3g.bnl.catwheezel@ID-107770.user.individual.net...
> On 2008-11-08, ian field <gangprobing.alien@ntlworld.com> wrote:
>> "Whiskers" <catwheezel@operamail.com> wrote in message
>> news:slrnghbb69.bnl.catwheezel@ID-107770.user.individual.net...
>>> On 2008-11-08, john downie2 <bluestar@mail.invalid> wrote:
>>>> my brother wishes wishes to take an Acer Aspire One mini-notebook to
>>>> japan,
>>>> from London, u.k. .
>>>>
>>>> He already has in his house a lead with a japanese type mains plug on 
>>>> one
>>>> end and the normal type two pin femail type plug (the same as often 
>>>> goes
>>>> into radios, etc) that will go into the computer transformer.
>>>>
>>>> But we see that the Aspire One has an additional *third* hole alongside
>>>> the
>>>> usual two hole plug that goes into the computer transformer. The three
>>>> holes
>>>> forming a triangle shape.
>>>>
>>>> Is it alright to use our existing two hole Japanese type lead and then
>>>> only
>>>> use *two* out of the three pins coming from the aspire transformer,
>>>> please?
>>>
>>> No.  If the power 'brick' has three pins, it has been designed to 
>>> require
>>> three connectors.
>>>
>>>> My guess is that the third hole is only an *earth* connection. although
>>>> this
>>>> might be an additional safety feature, our main concern is whether it
>>>> might
>>>> do any damage to use the two pin only lead?
>>>
>>> "Only" an earth?  Sheesh!
>>>
>>>> I have emailed the technical services department and the spares
>>>> department,
>>>> but neither will answer the question, only want to sell me one of their
>>>> three hole leads. Thanks for your advice.
>>>
>>> Assuming that your existing power brick can accomodate Japanese mains
>>> voltage and frequency, you will need an earthed Japanese plug to fit the
>>> Japanese mains socket.  Which sounds like what the technical services
>>> department are trying to convince you of.
>>>
>>> I think Japan uses 100V mains at either 50 or 60 Hz depending on 
>>> location.
>>
>> If the "power brick" is a switch-mode converter (not an iron cored
>> transformer) some types automatically adjust to anywhere between 100 - 
>> 240V,
>> check the specification label as this information should be clearly 
>> marked.
>
> True enough.
>
>> Most PSUs of this type are double insulated and do not require an earth,
>> they only have a 3-pin plug because the regulations in the country of use
>> say that all wall sockets must be 3-pin (there wouldn't be much point in
>> supplying items with a 2-pin plug that didn't fit anything).
>
> I took the OP to mean that the brick itself has three pins in the orifice
> to which the incoming mains lead is connected.  That suggests that the
> makers of it expected it to be earthed.

I'd still take it that if the original mains lead was only 2-core, even if 
there is a 3-way connector on the power brick, then you can't have live, 
neutral and an earth if there's only 2 wires in the mains lead. 3 pin 
connectors do turn up every now and then with only 2 pins actually used but 
they're not very common.

As long as the original mains lead is still with the power brick, its the 
best indication whether its safe to use without an earth or not. Of course 
with a detachable lead, if examination leaves any doubt as to whether its 2 
or 3 wires its easy enough to continuity test the earth pin.