48V hardware [RE-wrenches]

[Bill Brooks]

Windy,

I would be very careful suggesting any correlation of 125 VAC with DC there
is no good correlation between AC and DC on switches, circuit breakers, or
fuses. It must be tested and listed for DC.

Bill.


-----Original Message-----
From: Windy Dankoff, Dankoff Solar [mailto:windy at dankoffsolar.com]
Sent: Saturday, July 14, 2001 3:51 PM
To: RE-wrenches at topica.com
Subject: Re: 48V hardware [RE-wrenches]


Allan at Positive Energy wrote:


2. ...  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.



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.


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.


Windy
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