ESD Protection consumer product Joule rating required

[Jester]

I realize there is not a clearly defined answer to this question, I'm looking for advice.

For ESD protection of an exposed signal on a consumer product for example a RS-232 comm port signal or a USB power or data signal, where we can realistically expect the end user to take no precautions regarding ESD.

If we assume the TVS will be placed close to the connector say < 10mm, what is a reasonable rating in terms of Joules to provide enough protection to prevent ESD failures of the protected circuit?

A quick DigiKey search shows Joule rating ranging from 0.003 to 10,000J. I would think that a 3mJ device is better than nothing but I'm guessing it would not last very many ESD encounters?

 

[andre_luis]

If we assume the TVS will be placed close to the connector say < 10mm, what is a reasonable rating in terms of Joules to provide enough protection to prevent ESD failures of the protected circuit?

There are a variety of safety and electric protection standards, each one specified to be applied at specific environments which are normally subjected to different levels of energies, therefore this would depend on the testings defined for this case.