[R-390] R3 GFCI clarification

[Perry Sandeen]

Wrote:  OK, my biggest beef with the Y2K manual is the big bold safety warning on the first couple
pages that says "It should also be connected to a Ground Fault Circuit Interrupter.  If the radio
continually trips the GFCI check the line filter.".  The second sentence is extremely misleading
and potentially dangerous.<snipped>

This is a good point well taken.  This is being added to the safety section.  This was my line of
work for 25 years so it is learned facts, not an opinion.

Additional Safety Section
Here becomes the first of problems you will face.  A properly grounded R390 with the originally
installed line filter that is perfectly functional will trip the standard USA GFCI protected
circuit.  It does this as the filter design passes a little more than 5 Ma. to ground and the GFCI
trip current is 4 Ma.  GFCI protected circuits are a NFPA mandatory electrical code requirement in
new or remodeled construction for a number of years now in the USA. In most areas requiring
electrical inspection, it is law.  If the receiver is operated on 220 volts, the current leakage
doubles.
  
You have several choices.  One is to use an isolation transformer.  A second is to remove the
original filter.  This is not a particularly good plan as the original filter provided EMI
protection.  The third choice, which most chose, is to use a modern computer power supply filter
or an equivalent type low leakage filter mounted inside the chassis.

Danger: Under no circumstances should you operate the  receiver without a proven good ground wire
attached properly to the frame GND terminal 16.  

 "Electrocution" is a bit of a misnomer that isn’t self explanatory.  In most cases is actually
death caused by the heart rhythm being interrupted by 60 cycle current.  This is called
ventricular fibrillation.  The heart is still beating but the four chambers are not in
synchronization so blood is not pumped through the body.  You may still be breathing more or less
normally.  In this process you black out and in 3 to 4 minutes your brain dies due to lack of
oxygen.

Depending on the moisture of your hands, the quality of the alternative ground circuit, the
leakage through an ungrounded R390A with its original filter going in one hand and out through the
other (worst case scenario) has a very reasonable chance of killing you without blowing a fuse or
circuit breaker.

Danger: A variac is an adjustable auto-transformer and does not provide any current leakage
isolation.

Proven ground.  This is beyond scope of this manual.  Check with published references such as NFPA
or equivalent standards.

Regards, Perrier

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