Not defined in the NEC does not mean not enforceable, the very definition of a GFCI in the NEC uses the term "Class A".
Class A protection is not defined in the NEC, so by your logic GFCI is not enforceable?
The reason not is Article 100 states in part its "is not intended to include commonly defined general terms or commonly defined technical terms from related codes and standards".
The NESC and IEEE Green Book (IEEE Std 142) use the term objectionable current defined as any current that flows on normally non-current-carrying conductive paths, such as building metals or equipment grounding conductors (EGCs), during normal operation. Contrary to popular belief the NEC rule 92D does not allow objectionable current.
NEC section 250.6 (A) states:
In 90.5 the NEC does define the meaning of the term shall:
There are no exceptions to 250.6, its a fundamental part of 250.
A service fed by a long 3-wire SC cable from a EM disconnect, will cause a voltage drop (rise) on the neutral, that voltage is also present on equipment grounds.
Everything you expect to be electrically grounded can become a shock hazard.
In addition gas pipe especially CSST gas pipe becomes a parallel conductor.
Objectionable current on grounding and bonding paths like gas fittings can raise the temperature at a loose fitting enough to ignite combustible materials. Arcing at loose fittings is very dangerous as we all know.
Yes they are a hazard EM disconnects are the federal pacific panels of the 2020's, people will be correcting them for decades.
As far as the Class A GFCI, the informational note since at least the 2011 has told the code user exactly what a Class A GFCI device is.
As far as the objectionable current, we are not going to agree.
Can you show me a real world incident that was investigated by an electrical professional where there was a hazardous result of a parallel current path where the system neutral was not compromised?
The shock hazard is limited to the voltage drop on the service neutral and unless that neutral is compromised, there is not a real shock hazard. If there is a neutral problem on the line side of the main bonding jumper, there will be a shock hazard associated with everything connected to the electrical bonding and grounding system, even without a parallel path. If there is a problem with the neutral on the load side of the main bonding jumper, the parallel path might prevent damage to the electrical equipment connected line to neutral.
Every service in my area has code required parallel paths for neutral current as a local amendment requires all service conductors to be installed in RMC or IMC and there will always be neutral current flowing on the raceway between the meter and the service equipment.
The code required bonding of metal underground water pipes results in neutral current on the metal water piping system assuming the main is metallic like it is in a lot of older areas. The current on the water pipe is often 20 to 25% of the total neutral current if there are no poor connections on the water piping system. If there is a high impedance path via the water pipe, the current is very limited.
Same with cable TV where the shield in bonded to the electrical grounding system at every house and creates a parallel path for neutral current. I saw this path start a fire when the service neutral was open and there was no metal underground water piping system
CSST is so hazardous, it should not be permitted. That is exactly what the original investigations of fires related to that product said. When the CSST bonding requirements were submitted to CMP 5 for inclusion in the NEC, those proposals were rejected because the submitters could not provide any technical evidence the the bonding would prevent the CSST related fires. To this day, there are no special bonding requirements in the NEC for CSST.
