Re: Beating the electricity horse

> From: George Booth <booth at hpmtlgb1_lvld.hp.com>
> Date: Thu, 19 Dec 1996 15:19:01 -0700
> Subject: Re: Beating the electricity horse
> > From: svr at eecs_umich.edu (Steve Robertson)
> > Date: Thu, 19 Dec 1996 09:58:05 -0500
> >
> > [ Tirade deleted ]
> >
> > Why this tirade?  I just wanted everyone to be clear on the fact that the
> > real benefit of using a transformer for undergravel heating cables is NOT
> > that you reduce the voltage from 120 volts to 10 volts (or whatever).  THE
> > REAL reason is that you convert a potentially fatal AC line voltage to a
> > much less harmful DC voltage.
> Dontcha just hate it when a tirade goes wrong?
> The transformer typically used with heating coils converts 110VAC to
> 24VAC, not DC.  Most transformers that I know of are AC to AC.  Of
> course, there's that cool Transfomer that goes from an F-15 to an
> Amazon Goddess, but that's probably off the subject. <g>
> George

For DIY undergravel heating it is possible to get a switching power
supply (which outputs DC voltage) for the price of a transformer.
I used a 12v switching ps for my cables, and it has been working
for at least two years now.  Also,  a short on the output will be
less dangerous,  since it will simply shut down rather than heat
up like a transformer would.  The efficiency is about the same.