Allen,
I agree with your comments. Hi-pot is not, and never was, a reliable
"safe"/"unsafe" test. It merely finds component and/or finished goods
whose processes may have "crept" to non-compliance. For example, xfmrs
whose internal creepage/clearance distances between windings have crept
over from the original required values to less than required.
The ground continuity is a far more critical test, and can be performed
within the accuracy required with a small PAT.
One reason, I believe, that the standards do not address repair/service
actions and post-testing, is that there is no way the manufacturer or the
agencies can police this. Name one consumer product, no matter how complex
and possibly hazardous, that a consumer at one time has not tried to
repair.
Our products range in price from $50 to $10K. The low end units have no
service plan, only dispose and replace. All of the others can be
serviced by our authorized service centers, or by anyone else who wants
to hang out a "Service-R-Us" shingle. The agencies have no way to
control what independent after-market repair centers do.
However, if a company has rather tight control over the design,
installation, and servicing of its products, then it would be a good
thing to do hi-pot and earth resistance tests after servicing. For
example, a complex and expensive piece of unique manufacturing equipment.
George Alspaugh
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