The short version of what follows is that anyone who tells you to break the plug's Ground Pin, cut the Equipment Grounding Conductor (EGC), or open the EGC's connection to the receptacle by inserting a 2 to 3 wire adapter; without connecting it's grounding tab; in the cord to your radio equipment is engaged in a form of Wanton Reckless Endangerment. It will eventually get someone killed. That someone may not be the Amateur Licensee themself but a member of their family instead.
I also want to say that those who advocate such techniques in order to reduce your noise floor or audio artifacts, are also telling you that it is worth your life to accomplish that. But when they suggest it that is the detail that they leave out.
In the last couple of years some people who are very highly respected in the Amateur Radio Community have made some extremely dangerous suggestions about how to eliminate noise on your equipment's audio and lower the noise floor in your receiver. Because these folks are genuine experts in there respective fields other Amateur Licensees make the mistake that they know what they are talking about when they hold forth on electrical safety grounding being the villain of the piece in audio and receiver noise issues. Sadly that is not only untrue but the advise that they are giving out is deadly dangerous. You may conclude that I’m a bit of a fanatic on this topic and you would be right. I have served as a volunteer Firefighter and Emergency Medical Technician for 55 years in everyplace I have lived as an adult up until my retirement in 2015. In that 55 years I responded to several electrical shock injuries and at least 3 electrocutions. Such advice can and has gotten other amateur radio operators killed. One of them was one of the patients I transported to the hospital, doing cardiac compressions and forcing pure oxygen into his lungs, only to hear the doctor's inevitable words "Stop compressions. Time of death is..." One thing I can assure you is that telling someone that their spouse will never be coming home again is no fun at all.
It is nearly inevitable that a piece of equipment that you will use sometime in your life will come to have an energized exterior at a voltage which will be high enough to supply the 3/100ths of an Ampere that it would take to kill you. The only remaining question is how long that condition will last. With an intact, low impedance Equipment Grounding Conductor it will last less than a second and you will fix the problem or get it fixed. If the EGC has been cut, disconnected, or removed it will last for as long as that equipment is still connected to the energized conductor (Hot). That gives you days or weeks or even months to come in contact with it while you are also in contact with some other conductive object such as any piece of equipment in your station connected to an antenna lead in. Given that you will have a protective device on the lead in and that you will have made sure that is grounded it will carry that 30 milliamperes that will stall your heart and take your life.
I cannot ask that father of 2 whether it is really worth the risk of death to lower the noise floor on his receiver. But he got that deadly idea from someone and their casual thoughtlessness still makes me angry.
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Tom Horne W3TDH