[SML] Electrical question

[FBC Tech Team]

Likely it was the ones that were plugged in that were “completing the
circuit“. Unplugged adapters have an open circuit on one end so there’s no
current flow when they’re plugged in. When they’re plugged into some thing,
then there is the opportunity for current flow. When the power comes back
on, you get an inrush of current through the adapter to the connected
device.

Transformers initially act as a short to incoming voltage because they’re
just a piece of wire and it takes a short bit of time for the coil of wire
to build up its magnetic field, which in turn creates impedance (AC
resistance) to limit the flow of currents to what it is designed to
handle.  So it’s possible that when the power came back on, all those
adapters that were plugged into something suffered from that large inrush
of current.

I would recommend next time that you have a power outage to unplug any of
those types of adapters before the power comes back on to limit the
possibility of damage. Larger power bricks aren’t as susceptible as they
have more circuitry built in to withstand the current rush, but smaller
wall adapter is not so much. This is also why it’s recommended to always
use the on/off switches on electronic devices instead of switching a power
strip or outlet switch on when turning on devices.

Hope that helps,
Jeff


On Tue, Aug 16, 2022 at 08:28 Paul Guncheon via Stagecraft <
stagecraft at theatrical.net> wrote:

> Kinda off topic: I had a power outage at home that lasted about 6 hours.
> After the power came on, I discovered that three wall warts (the ubiquitous
> plug-in transformers) were dead. As I hadn't used the devices that these
> wall warts powered all that often, it was days or weeks after the power
> outage that I found out so I'm not sure that the power being turned back on
> was the cause. Is it possible that it was? Note that several other
> transformers, notably Apple device chargers, were not affected. However,
> the ones that died were connected to devices (they were not powered on at
> the time) but the Apple chargers were not connected to anything.
>
> One of the ones that died powered my doorbell... which is why this is so
> curious. The other two were less than two years old.
>
> -p
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-- 
-------------------------------------
Jeff Klein, DMC-E
Head Volunteer AV Geek
Faith Baptist Church
Glen Burnie, Maryland
(Website / Twitter)
http://www.faithbc.net / @FBC_TechTeam
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http://www.linkedin.com/pub/jeff-klein/32/852/6ba

"Clothe yourselves, all of you, with humility toward one another, for God
opposes the proud but gives grace to the humble." 1 Peter 5:5
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