🚀 go-pugleaf

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.  

Both the laptop power bricks in use in this room (one HP, one Toshiba) have
three metal pins for the mains lead to connect to - and /do/ require an
earthed mains lead and socket.  The arrangement is sometimes described as 
a 'cloverleaf' connector; more officially an IEC-320 type C5
<http://www.maplin.co.uk/images/full/qn62.jpg> and 
<http://www.maplin.co.uk/Module.aspx?ModuleNo=218969>.  The two-pin type
with no earth is a 'figure-of-eight' or IEC-320 type C7.

Here in the UK, double-insulated appliances can be fitted with a mains 
lead that has a plastic 'earth' pin - whose functions are to open the 
shutters on the other two holes in the socket, and to ensure correct 
connection of the 'live' and 'neutral' pins.  But mere presence of a metal 
earth pin on the plug cannot be taken as evidence of an earth connection, 
of course!

> Carefully 
> examine the mains lead, if its round then it contains 3 wires and must be 
> earthed, if the mains lead is flat so you can tell the outer covering is 
> over a pair of wires side by side then there is obviously no third wire for 
> an earth. 

Never seen a 'flat' three-conductor lead, or a round two-conductor lead?

-- 
-- ^^^^^^^^^^
--  Whiskers 
-- ~~~~~~~~~~