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Re: [APD] Re: incandescent-replacement type fixtures -- or - scaring the living day lights out of me

I wasn't recommending that anyone switch on the High
voltage side. So i hope know one reads that from my posts.

I fear my comments a few  posts ago did suggested to at
least one reader that swtiches on the output side were
something one could sneeze at. Certainly one should try
anything at all with anything that connects to house
current unless they know ahead of time all the parts to use
and what will happen. Leave the experimentation to the
enigneers and any wiring with which you are unfamiliar or
uncertain to a qualified electrician. If you're doing DIY
with manufactured items electrical, follow the
instructions, much of which was written by lawyers to
protect the manufacturer from lawsuits and you from
excessive electrical stimulus or sedation.

Oh, and sorry I scared you, Bill. Go watch your fish for a
while; watching the fish always makes me feel better ;-)

Scott H.

--- Bill Wichers <billw at waveform_net> wrote:
> >The right value capacitor across the switch terminals
> can
> >prevent momentary arcing that's due to the switch
> contacts
> >almost touching during part of the switching cycle. They
> >highrer the voltage the wider the gap the arc can reach
> >across. What value capacitor will prevent the arcing on
> the
> >output, high voltage side, depends on the ballast and
> bulb
> >operating characteristics. Maybe one of the EEs can help
> >you there.
> OK, this is getting scary... You should *NOT* be
> switching the OUTPUT 
> (lamp) side of the ballast! On an instant-start ballast
> you can get pulses 
> of many hundreds, maybe even upwards of a thousand volts
> in some cases 
> during the "start" pulse. You would need a kilovolt level
> pulse-rated 
> switch for this which is neither a common nor a cheap
> item. A regular lamp 
> switch will normally be rated for 300 volts (the minimum
> UL and the NEC 
> allows), or  600 volts for the better ones -- and
> prolonged arcing will 
> quickly destroy them.
> A capacitor will help to reduce the RFI (Radio Frequency
> Interference) 
> emitted by the arc but will not necessarily prevent an
> arc from occurring. 
> Typically a ceramic disc capacitor of about 0.01
> microfarads is sufficient 
> to keep the RFI down, and these capacitors are cheap and
> durable. They 
> aren't particularly necessary unless you expect the
> switch to change state 
> slowly (think thermostat in a heater that doesn't "snap"
> over but takes a 
> little while to change from "off" to "on" and vice versa)
> and thus arc for 
> a little while during each state change.
> >Whether the Ballasts are remote mounted or not shouldn't
> >affect whether the on/off switch arcs *if* the switch is
> on
> >the input side of the ballast.  I'd rather have my
> switches
> >on the input wires and run the wires to where I want a
> >switch than put the swtich on the wires that are closest
> --
> >I'd rather not fiddle with the high voltage if I don't
> have
> >to and I only have to intall the wires once.
> In no case should you switch the output side of the
> ballasts. If you use a 
> remote-mounted ballast, either mount the switch on the
> ballast enclosure or 
> run an extra pair of wires to the light hood so that the
> switch can be 
> mounted on the hood but still switch the power on the
> *input* side of the 
> ballasts. Some ballasts will fail if left open-circuit
> for a long time 
> (with either a bad bulb or "turned off" on the output
> side). If I remember 
> correctly, some of my MH ballasts actually state that
> they draw *maximum 
> current* when the output is open-circuit!
> BTW, you could solve this whole problem by just using a
> timer to control 
> the lights and then not need a "switch" at all. Might be
> worth considering...
>          -Bill
> *****************************
> Waveform Technology
> UNIX Systems Administrator
> _______________________________________________
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> Aquatic-Plants at actwin_com
> http://www.actwin.com/mailman/listinfo.cgi/aquatic-plants

S. Hieber

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