🚀 go-pugleaf

In article <1992Dec18.081530.13580@netcom.com>, nagle@netcom.com (John Nagle) writes:
> 
> more_da@pts4.pts.mot.com (Dan Morera) writes:
> >Greetings and Happy Holidays Netters,
> >I am developing a system to remotely control a hot tub, and I have not
> >previously worked with the large AC voltages needed to do so.
> 
>      Given your discussion, I suggest you get a licensed electrician to
> do the job.  You've missed a few key safety issues.
> 
>      This is NOT to be taken as a complete list, but first, where you
> have water near power, you're usually required to use a GFCI breaker,
> and for a hot tub, you definitely should.  Second, you need low-water
> and overtemp detectors for the heater to prevent fire should the water
> stop flowing or be absent.  Most hot-tub heaters have these built in,
> but check.  Redundant overtemp switches are common, and may be required.
> 
>      Switches where a wet person can reach them require special handling.
> The usual hot tub switch is an air button, a squeeze bulb connected by
> a tube to a pressure switch.  Just putting the controls on the +5 supply isn't
> good enough, because something might short to the low-voltage portion of
> the system.  UL-approved switches for very wet locations exist, but
> are expensive.
> 
>      And remember, plumbing isn't ground in the era of plastic pipe.
> 
>      Have you figured out how much it will cost to heat a hot tub
> electrically?  Most people use gas or solar.
> 
>      Go with an electrician.
> 
> 					John Nagle
> 
> 
>
Just one thing to add to John's recs....  It's wise to separate the low-voltage
from high-voltage circuitry with opto-isolators as an added precaustion! 

Otherwise, I'd follow all of his recs!  

-Jeff