[ale] Preventing reboot on short duration power loss

[Richard Bronosky]

I'm straying off topic a bit here, but I feel this is a good
opportunity to share a little info about household wiring. The
neural/white wire should be considered "hot" on a circuit unless the
main breaker, or"whole house" switch, is switched off at the box. This
is because all of the neutral are connected together via the neutral
bar, seen here http://www.lowes.com/lowes/lkn?action=howTo&p=Improve/220outlet_breakerbox.html
So, if you have a single electrical device in your entire home
(refrigerator) drawing power, the black wire and the white _wires_
(all of them) are connected. If that is not clear to you, realize that
a light bulb, motor, etc. is just like a fancy wire connecting a
circuit. See: http://www.gcse.com/gcse_science_physics_past_paper_j03_6.htm
I often wondered why the white wire would shock me when replacing
light fixtures, even when turning off the breaker for that room. Once
I opened up the breaker panel to add circuits, I understood. Now I
just replace fixtures without even flipping the breaker. I've been
shocked so many times I don't even jump anymore.

I share this because if you do not know this and you grab (instead of
touch) the white wire while touching anything grounded you are likely
to have your muscles clinch and not be able to let go. That is how you
get killed with household voltage.

On Sat, Jul 4, 2009 at 7:49 PM, Quentin
Schander<Quentin.Schander at eastcobbgroup.com> wrote:
>
>
>>>> On 7/4/2009 at  6:34 PM, in message <20090704223402.GA26602 at epona.localdomain>,
> Andrew Grieser <agrieser at gmail.com> wrote:
>> Thanks to everyone for the advice. I bought one from Microcenter earlier this
>> week, and went to hook it up when it complained the outlet wasn't grounded.
>> Turns out, even though the outlet is a three prong outlet, it wasn't actually
>> grounded. So I had to ground it (thus the delay), but now everything seems to
>> be working. I just unplugged it from the wall, and it switches over to
>> battery no problems.
>>
>> I did buy one with an AVR because, daily, my confidence in the power grid
>> around here is lowered.
>>
>> I have one last question. If this outlet wasn't previously grounded, would
>> the surge protector have even worked? Do surge protectors work on ungrounded
>> outlets?
>
> I expect that it would have worked but not perfectly.  The ground (or green) wire provides access to ground potential over a non load carrying wire.  The neutral (or white) wire is grounded too but must also function as the return leg for the current flowing in the circuit.  Faults can arise which diminish the effectiveness of the ground connection of the neutral wire.  Cheap surge protectors only have protection between the hot (black) wire and the ground wire.  Better surge protectors have protection between all three legs of the circuit.  Without a ground leg in the circuit, a cheap surge protector would have been ineffectual while a better surge protector would have been able to dump at least part of the surge to the neutral leg.
>
> Quentin
>
>
>>
>> Andrew
>>
>>
>>
>> On Sat, Jun 27, 2009 at 02:36:58PM -0400, Richard Bronosky wrote:
>>> I wouldn't spend my money on an UPS without AVR. In fact, what you are
>>> experiencing may be a brown-out instead of a black-out, and a UPS may
>>> not even activate.
>>>
>>> On Sat, Jun 27, 2009 at 2:14 PM, Jason Fritcher<jkf at wolfnet.org> wrote:
>>> > On Jun 27, 2009, at 1:51 PM, Andrew Grieser wrote:
>>> >> Because this seems to happen somewhat often, I need a way to keep
>>> >> the computer running through a short duration power loss. Any advice
>>> >> on choosing a UPS? It honestly only has to last about a second, with
>>> >> about a 200 watt load on it.
>>> >
>>> > I've always been partial to APC UPSes.
>>> >
>>> > If your load is under 200W, try this...
>>> >
>>> > http://microcenter.com/single_product_results.phtml?product_id=0286288
>>> >
>>> > If it is over 200W, then I would go with this...
>>> >
>>> > http://microcenter.com/single_product_results.phtml?product_id=0286289
>>> >
>>> > The first does not have a data port for a controlled shutdown before
>>> > the battery dies. If that is an important feature, then go with the
>>> > second which does have the needed data port.
>>> >
>>> > --
>>> > Jason Fritcher
>>> > jkf at wolfnet.org
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>
>
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