[MrFixr55]

Hi Klondike,

Unfortunately, there will be leakage.  The culprit is not C5 as this goes to "B-, A-, Common, and only when the switch is on. The Culprit is Cap E1.  This is a "warm chassis" set.  Note the capacitor "E1" is connected between B= and the chassis.  The purpose of this cap is to allow RF energy (i.e. the tuning cap and chassis ground, indicated by the typical ground symbol) to connect to A- / B- (Indicated on the schematic as arrows).  If the cabinet is metal, it appears that the chassis is not well insulated from it.  To make matters worse, like almost every AA5 radio and almost every "3 Way" (AC/DC/Battery) radio, the AC line is "Neutral switched", not "Hot switched"  In other words, the leg of the power cord that goes to the common B- and A- (for battery sets) or B- and 1st AF amp end of the filament string on AA5 and AA6 sets goes through the power switch first.  Therefore, if this leg is at "Neutral" potential, with the switch on, the chassis is at neutral potential (which is ground potential as neutral is tied to ground at your fuse box or meter panel) and you will not feel a tickle (or outright shock) with the switch on.  However, with the switch off, leakage through the rectifier / condensers and tube filaments on this sets or the filament string on AA5 sets will cause the chassis to be "warm".  Using a DVM, you will likely detect 120VAC between the chassis and ground with the switch off and 0V with the switch on.  Reverse the plug and the opposite happens (0V with the switch off, 120V with the switch on.

The issue is not the voltage; it is the allowable current leakage.  It is possible to detect a rather high voltage using a DVM because its input impedance is very high.  Later Sams Photofact schematics instructed Service Techs to measure leakage by measuring voltage across a resistor connected between exposed metal and ground and calculate via Ohm's Law.  if you use a 1K Resistor, the voltage displayed will indicate mA.  For example, 1V across a 1Kohm resistor is 1/1000 Amp or 1 Milliamp (mA), or 1,000 microamp (uA).  The following may help:

• The IEC60601 current specification for most electronics in a patient care area but not having patient contact is 500uA or 0.5mA. 
  

• The IEC61010-1 Standard for consumer electronics is 500uA normal leakage and 3,500uA (3.5mA) for a "single fault" condition.
  

• A "Class A" GFCI (Ground Fault Circuit Interrupter), the type found in most kitchens and bathrooms trips at 4-6 mA (4,000-6,000uA)
  

Of course, what passed UL (Underwriters' Laboratories), or CSA (Canadian Standards Association) inspection in the 1940s and 1950s likely won't cut the mustard today.  Looking at some of the last tube radios of the 1960s, one will find plastic control shafts, no external contact to the chassis, knob clips that prevent removal of the knob from the case and fully enclosed cabinets with very thinly spaced ventilation louvers.

Hope this helps.