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Re: Aquatic Plants Digest V4 #1446/connectors

>300V for line voltage devices is a safety margin--but ballasts raise
>the line voltage.  I believe some flourescent (and other arc-lamp)

Arc lights like MH and HPS usually run around 70-150 or so volts but have a
striking voltage of sometimes upwards of 1000v. The 300v number is in the
NEC book, and is typically about 10-25% of the breakdown voltage of the
dieliectric used in the connector. Thus, it is safe to assume a 300v
connector can handle about 1200v to 3000v without flashing over, but
obviously this isn't something you would want to do all the time. I usually
see 300-600 volt wire (600 volt is the highest UL rating for regular wire,
BTW, and is the highest "normal" distibution voltage used in buildings)
used on even 1000 watt MH lighting, the idea being that the dielectric in
the cable will not break down in the few seconds that the lamp takes to
strike with a very high voltage.

>ballasts drive the lamps at about 600v.  With Voltage it's best to err
>on the side of caution.  So you might want to wrap connectors rated for
>a lower voltages in insulating tape.  That makes them less quick to
>connect or disconnect but who thinks a Jacob's Ladder is attractive on
>an aquarium.  

That would protect users but would not effect the breakdown voltage rating
of the connector's insulation, since you can not add more insulating
material BETWEEN the contacts of the connector. Certainly no problem using
a beefier than necassary connector though :-)


Waveform Technology
UNIX Systems Administrator