Re: substrate heating cables

    > From: trigg at jane_cs.waikato.ac.nz (Len Trigg)
    > A couple of weeks ago I was in our local fish shop and mentioned
    > to the owner about using substrate heating cables for plant
    > tanks, and from the back of one of his shelves he pulled out a
    > 25W heating cable made by an outfit called Renacor (or something
    > like that - I can look it up when I get home).  He said he'd had
    > it sitting there for ages. ...
    > The main difference between these cables and the Dupla/Dennerle
    > systems is these use mains voltage rather than low voltage (which
    > in turn means lower current than Dupla/Dennerle).  I'm not sure
    > what this means safety-wise (I think that lower currents are
    > less likely to kill), but I plan to use a GFI for safety anyway.


    I *would not* put 120VAC heating cables into an aquarium, GFCI or not.
    Yeah, the current is the bullet that kills you, but it's the voltage
    that pulls the trigger.  Example -- a car battery can dump a kiloamp
    with ease, but it doesn't have enough voltage to push that current
    through your body resistance, so you can safely pick up the charged
    battery by its bare terminals without lighting up your life.  If you
    could find a *really* high-wattage 120VAC cable, like a kilowatt or
    so, you might be able to get a decent amount of heat from it using a
    24V transformer or some other low-voltage device, but I doubt that
    you'll find such a cable.

    -- Keith

    | Keith Brummett            Ofc: 614-860-3187         AT&T, Room 3B202 |
    | w.k.brummett at att_com      Fax: 614-868-4106        6200 E. Broad St. |
    | wbrummett at attmail_com         R,DW,HAHB!          Columbus, OH 43213 |