I have a Malibu 12V transformer/timer I use for regular outdoor
lighting. Works fine. I recently installed a pond, and would like to
attach some submerged 12V lights to the transformer. However, I
notice a sticker on the transformer stating "Not for connecting to
underwater lights". At the Intermatic (Malibu) site, it states in the
instructions for my transformer that it doesn't have a "ground shield"
and thus is not designed for working with submerged lights.
Question: Anyone know what this "ground shield" is? If I connect it
to a GFCI outlet, will I be safe to use it anyway, underwater, or will
my fish (and I) fry?
Might go buy a pool light transformer, usually 300 watts & cheap enough.
Shield completely isolates Hv from Lv windings - grounded sheet metal plate
between Hv/Lv windings - Malibu winding short on either side the A/C
will/could juice up the lv and kill your fish and the neighbors kid due to
whatever,,, hungry bugs, rust, lightning, defective varnish, fertilizer
burn, chemical corrosion, wives driving abilities, etc.
email@example.com (Greg) wrote in message
Hmm, still stumped here. I know I could just buy a new, grounded one,
but something just doesn't seem right here.
If the non-grounded, non-shielded 12 volt transformer I now own is
such a hazard, and if there is a short with it, then how is that any
different from the other 120V submersible devices currently in my
pond, which are not grounded at all? I'm referring to the pump, as
well as a low-water shutoff switch. Both have no third grounding
prong, and are only protected by the GFI.
Of course I want to do the work to code, but there doesn't seem to be
any rhyme or reason to it here...
Your 120v pump and low-flow cutofff are UL listed as "submersible" and designed
and built to operate safely under water. It has nothing to do with the fact
that they're grounded or not grounded.
Underwater low-voltage lights are designed and built with NO protection between
the exposed low voltage electrics and the water, and because of this, require a
transformer which, amongst other things, does have a grounded metal shield
between the primary and secondary windings of the transformer.
If the shield was not present, in the unlikely event of transformer meltdown,
there exists a slight possibility that the line voltage windings on the
transformer core could liven the core to 120 volts, and in turn pass that 120
volts right into the low voltage winding and into the pond water, right through
the water via the non-watertight terminals of the submersible lights and
oftentimes, submersed splices.
BTW, most outdoor L.V. transformers 300 watts - 600 watts are only available in
the better, shielded/grounded versions. It is only the 88-180 watt cheep-o's
that come in both varieties because, it's probably a dime cheaper to make the
more common, less safe variety that's included with every piece of crap plastic
landscape lighting kit.
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