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Wow, Michael, look at the monster you have created, Dr.
Frankensolarbozo! <br>
Yes, that's the thread. And I was about to post that Windy left today
for Costa Rica...just a trip, not a move.<br>
William, there are certain perfectly appropriate applications - such as
a pressure switch controlling a DC pump, or an A/C disconnect (Square D
CU200) 2-pole array disconnect for an array-direct pump. Historically
there was nothing DC-rated available, and conservative use of available
AC equiipment worked fine and lasted forever. Sometimes it just don'
matter how it's Listed, ya just gotta use it...ya know?<br>
Allan<br>
<br>
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<p class="MsoNormal" style=""><span class="il"><b style="">Allan</b></span><b
style=""> Sindelar</b><span style="font-size: 10pt;"><br>
<a href="mailto:Allan@positiveenergysolar.com" target="_blank"><span
class="il">Allan</span>@positiveenergysolar.com</a><br>
NABCEP Certified Photovoltaic Installer<br>
EE98J Journeyman Electrician<br>
<b style="">Positive Energy, Inc.</b><br>
3201 Calle Marie<br>
Santa Fe, New Mexico 87507<br>
<b style="">505 424-1112</b><br>
<a href="http://www.positiveenergysolar.com/" target="_blank">www.positiveenergysolar.com</a></span></p>
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<br>
<br>
Michael Welch wrote:
<blockquote
cite="mid:20100514003038.13D345F598@friskymail-a1.g.dreamhost.com"
type="cite">Is this conversation what you were refering to? 7/22/01<br>
<br>
Others offered caution to this approach, but clearly the subject was
switches, not breakers.<br>
<br>
Allan at Positive Energy wrote:<br>
<br>
<blockquote type="cite" class="cite" cite=""><font size="2">2. ...<i>
</i>I am using float switches to control 48V mercury displacement
relays
for these DC pumps. Can anyone suggest a source of SPST, SPDT, and DPDT
bat (or any style) switches suitable for 48VDC nominal, low current
loads? These would be for a custom relay control enclosure with
override
and remote low tank alarm signal circuits.<br>
</font> </blockquote>
<br>
My frequent observation on DC ratings for mechanical switch contacts is
that it's amp rating at 125VAC equals its amp rating at 28VDC. This is
consistent in the specifications of a great many switches, relays, etc.
If there are higher voltage ratings, then if voltage is doubled,
amps is half.<br>
<br>
When 48V is not specifically listed (nor any higher DC voltage), I feel
safe following that rule if I apply a good safety margin, as long as
the
switch has a rapid snap action like a toggle switch does. For the low
current control and alarm loads you describe, I would feel forevever
safe
using a switch with a 15A rating at 28VDC. If you need to get official
approval, ask the manufacturer of the switch you propose to use.<br>
<br>
Windy<br>
<br>
<br>
Bill Loesch wrote at 05:10 PM 5/13/2010:<br>
<br>
<blockquote type="cite" class="cite" cite=""> <br>
Fellow Wrenches,<br>
<br>
Some time ago, Windy Dankoff had a rule of thumb to substitute
(conservatively) an AC breaker for use in a DC application. <br>
<br>
Is anybody's memory, or perhaps even the old dog himself; if he is
listening, better than mine?<br>
<br>
TIA,<br>
<br>
Bill Loesch<br>
Solar 1 - Saint Louis Solar<br>
314 631 1094<br>
<br>
<br>
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