Maynard G. Krebbs wrote:

On Mon, 06 Sep 2004 20:04:20 +1200, Steve wrote:


I am building a new 12V DC switch panel for my boat and have a load of
switches rated at 10A@125V or 8A@240V. Although they have 12V
illumination there is not a DC rating in the datasheet. Does anyone have
any idea what sort of rating can I assume for low DC voltage or are they
totally unsuitable?

The switches are Cherry RRA22H3BBRHN rocker switches.

Thanks in advance,

Steve


I've always been told to use DC switches and breakers on DC.
The arc is harder to break because there isn't a null period in DC
like there is in AC.
I wouldn't use them unless they are rated for Direct Current.
Mark E. Williams

One way to help switches in DC circuits is to connect a capacitor
across the switch. It sucks up the last bit of current as the
switch opens, helping to prevent the formation of an arc. Fast
acting 'snap' switches last better in DC. A few microfarads,
properly polarised (positive towards the positive battery) can work
wonders. I would try your switches, make them changeable and carry
a spare for critical applications. They may survive the duty and
conditions you throw at them, if not, go upscale. Try one. Work it
to death. The rating is only intended to indicate safe working
current, not indicative of arc tolerance, which usually means
beefier contact and actuator design, heavier case, toggle, etc.

A shorted arc suppression capacitor becomes a stuck 'on' switch in
circuit.

DC and inductors like solenoids are a bitch on switches. A starter
switch comes to mind as possibly the most critical. But, remote
switching is only a luxury, non? There is always the modified hammer
tool for jumping starter solenoids.

A few wire nuts aboard, or even electrical tape can save an
electrically challenging day.

Terry K