Doesn't connecting genset (with neutral bonded to frame) to house service using typical 2-pole x-sfer switch (only switching 'hot' phase conductors) create objectionable current flow, allowing current back flow (through service neutral) out to street potentially causing damage/injury?
There may be some small amount of current through the parallel paths, but the only voltage that is available to drive this current is the voltage drop on the grounded conductor. This should not be enough to cause any safety issues.
Shouldn't (1) the neutral be disconnected from genset frame; (2) new grounding electrode (I.E. driven ground rod) and GEC for genset be installed; and a 3-pole pole double throw x-fer switch (switching neutral) be installed?
The code does not require that the neutral be switched if remove the bond at the generator. That is only required when the generator is set up as a SDS.
Isn't this why on permanently installed gensets the neutral is switched?
That is a design issue not a code issue. If the generator is set up as a SDS, then you need to switch the neutral. If it is not set up as a SDS the neutral is not switched. Most of the ones I have been involved with were not set up as SDS.
Isn't a "portable" genset connected to a permanent x-fer switch and permanent house wiring through 4-conductor cord set in effect a "separately derived system (I.E. genset never moved/used with extension cords on construction sites)? Homeowners are opting for larger (I.E. 10 KW) portable gensets (instead of permanently installed gensets) due to cost and other issues. These "portable" gensets are usually connected via hard-wired 2-pole x-fer switches to back up crutial circuits.
If the neutral is bonded at the generator then it is SDS.
How is a 10 KW "portable" gasoline genset suppling phase, neutral and grounding conductors through 4-wire cordset to 1-family house any different (in practice as opposed to NEC's def) from a 100k kw standby diesel genset powering large building?
Its not, but tell me why multiple bonding points on the line side of the service are permitted if that is such a big hazard.