On 8/1/09 4:49 , Richard L Ratico wrote:
2)At a different training, by a well respected professional engineer who frequently posts here, they were judged to likely be as effective in preventing damage as a voodoo doll.
I'm not disputing this, but would like to know more. Perhaps our PE will elaborate.
4) Why aren't they UL listed?
According to Delta, it's because they don't fail on normal surges and that is required as part of UL 1449. http://www.leainternational.com/UL1449.aspx mentions it starting in 2007:
/Now, when UL tests a SPD, they will apply a fault current of 100A, 500A and 1000A for permanently connected SPDs and 50A and 150A for plug-in and cord connected SPDs. These currents are applied using line to line voltage in the line to neutral mode. During this testing, the SPD must fail in a safe manner to be UL 1449 listed.
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