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My reasoning was that of guarding against those (admittedly rare, but possible with devices over 50 years old) cases of dielectric breakdown between primary and core of power transformers. Another possibility is that, perhaps several years after new caps are installed, the line bypass caps develop leakage to produce a shock hazard during hookup to a well-grounded antenna system if the set is plugged in and one touches the antenna terminals and antenna lead-in wires simultaneously before the two are actually connected.
A number of rules were adopted and/or amended regarding consumer products for US markets, most notably those enacted and/or amended in 1968, 1972, and 1976. Without re-checking my original sources on these, I don't recall which year corresponds to which rule or amendment. One was an amendment to FCC Rules Part 15 regarding interference with other systems and governed TV, radio, and other RF-producing appliances, presumably tightening restrictions upon RFI. The other two rules and/or amendments were in reference to product safety. As I recall, one dealt with X-ray emissions from television HV components, later amended to set stricter limits. The other specified maximum ground fault tolerance in terms of maximum AC voltage permissible between exposed metal parts of any device and earth ground as measured across a specified RC test circuit, and was later amended to set more-stringent limits. If memory serves correctly, the ground fault limits specified in 1968 allowed 7.5VAC across an RC circuit consisting of 1500 ohms shunted by 0.15uF and the 1976 amendment lowered the maximum permissible voltage drop to 1.5VAC.
I have encountered some equipment having relatively large line bypass caps, and a bypass cap of about 0.05uF has 53K capacitive reactance at 60 Hz. Such a reactance value could pass enough leakage current to exceed safety guidelines, although probably not enough to cause serious harm or even to trip a GFCI. If the caps developed significantly-low DC leakage resistances in 20 years or so from now, though, a very unpleasant shock could result from simultaneous contact with the TV chassis and, perhaps, a nearby heating duct or radiator as such structures would be made of metal and in contact with the furnace or boiler which would in turn be grounded. Perhaps not an electrocution risk for a healthy adult, but potentially an unpleasant surprise.
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