Quote:
Originally Posted by Electronic M
I know this is a settled matter, but there's one thing I find odd. Your assumption that an isolation transformer will pass it's plugs ground through to its outlet and that the VTVM would have a 3 prong cord... While I wouldn't doubt there are ones that do out there somewhere, I've never seen an isolation transformer built that way out of better than half a dozen I've had. Most isolation transformers I've seen don't have 3 prong cords and many that do don't ground the outlet or use a 2 prong outlet.
Likewise the vast majority of VTVMs made are only 2 prong...It wouldn't surprise me if some lab or mil spec units or some last gasp 80s units might have been built with 3 prongs, but that seems like assuming the exception rather than the rule.... Better to assume the rule and warn to check for the exception in most cases.
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You unfortunately misinterpreted what I said. Look at the instructions in manual for adjusting traps. I said the isolation transformer will not prevent the measurement from being a shock hazard.
And my Heathkit VTVM I bought new in 1971 was provided with a power plug third prong or ground. My three earlier VTVMs (two RCA's and a 1950 Heath) did not have the ground connection but my later Heathkit one did.
I only had to emphasize that the dangerous measurement using a VTVM with a metal case at 120 volts B minus potential can cause quite a jolt and one must be aware.