I would have thought a question like this was off-topic, but I will
assume it is not if my answer gets approved by a moderator.

If the devices are fairly new and have markings on them that indicate
that they have been inspected and approved by a recognized
agency, I would assume from the facts presented that the manufacturers
and the inspection agency felt it not necessary to identify and keep
track of the neutral or hot wire through the use of a polarized plug.
Generally speaking, transformers are used for isolation (and of course
transforming...)  Since there are always exceptions to every rule,
especially on cheap, un-inspected, or defective equipment,
I would not take this as "the gospel" or risk my life on it...
                Rick Glazier

----- Original Message -----
From: "Mark Rode"
> 120 >> 12 volt transformers for PC devices such as hubs, speakers and
> modems never have polarized plugs.
> However I have always made sure that the transformers are plugged in at the
> correct direction relative to the printing on the device so as to put the
> hot lead on the right. This is not always easy to arrange without loosing
> some outlets on a surge protector or UPS.
>
> Because the transformers never have polarized plugs I am not sure that this
> is in fact necessary ?
> Is this a good idea or does it matter ?

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