At 08:41 PM 2/12/01 -0500, you wrote:
>I find it interesting that your example of  uses a 600V spike. When I
>was working on a PIC based product design a few years ago, UL wanted it
>to withstand a 600 V spike, but they couldn't really say why. That's
>just the standard. That bugged me. So I did some research & finally
>found out why in a Harris MOV manual. 600 V is the arc over voltage of
>the standard wall outlet. If it's greater than 600 V, it doesn't get to
>your power supply, it arc's over the screws of the oulet. That's
>something I would not have thought of.

Hi, you were probably thinking of 6,000V (peak), which would agree
with  IEEE Recommended Practice on Surge Voltages in Low-Voltage
AC Power Circuits  (IEEE C62.41-1991, formerly IEEE Standard 587).

[You should allow for up to 6,000V peak (open circuit) for both
Category A and B transient events; and short circuit currents
can exceed 500 and 3,000 amperes respectively. In a category B
event, the rise to 6kV can happen in 1.2 usec.]

If your resistor(s) and whatever else you use can survive that,
it should be pretty reliable in practice.

Best regards,

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