Thanks. I'm just in high school so I only understand the basics - a full
explanation is good for me to know.
Peter
----- Original Message -----
From: Clark Martin <[EMAIL PROTECTED]>
To: G-Books <[EMAIL PROTECTED]>
Sent: Friday, July 06, 2001 8:32 PM
Subject: Re: Recall on AC adaptor for older G3s
> At 5:55 PM -0500 7/6/01, Peter Graening wrote:
> >Everyone is talking about these adapters being cool - but the problem is
the
> >ones that Apple is recalling don't have a grounding plug. Check and
see -
> >all of the adapters for PPC PowerBooks that I have seen have come with a
> >grounding plug somewhere on the plug - and even if this grounding isn't
> >transferred to the computer - it could have some function in the
adapter's
> >circuits. As far as I recall, it's not safe to use a piece of
electronics
> >without a proper ground - even laptops. Perhaps someone on the list
knows
> >more about this and could elaborate on this for me.
>
>
> There are two reasons for a grounded plug. The reason grounding was
> first done is to protect against electrical shock. Whether a device
> is grounded depends on a lot of things but mostly on the likely hood
> of a fault developing which could cause an electric shock. A
> computer really doesn't need grounding for this reason, it's as
> likely to get a hazardous fault as a stereo component.
>
> The other reason is to provide a common ground between all
> components. Without this some parts could have excessive noise
> injected into interfaces causing problems.
>
> A laptop's power supply is usually a separate unit (a brick or wall
> wart). These don't need grounding for safety reasons (most other
> wall warts don't have a ground). Most of the interfaces a laptop
> uses are less sensitive to ground differences. Phone, Ethernet are
> both fairly well isolated. I don't know about USB or Firewire but
> they are probably too.
>
> A laptop's power supply really doesn't need a ground. Some have it
> but that's more a decision by the designers. One reason to NOT have
> a ground is that laptops are frequently used where there isn't a
> ground.
>
> BTW, I'm an Electronic Engineer with a reasonable understanding of
> the NEC (National Electrical Code).
>
> Barring a major fault a lack of ground would not cause overheating.
> --
> Clark Martin
> Macintosh Consultant
> Another designated driver on the Information Super Highway
>
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