From: hornetd@gmail.com
On Friday, January 4, 2019 at 7:46:29 PM UTC-5, gfre...@aol.com wrote:
> On Fri, 4 Jan 2019 09:35:58 -0800 (PST), Tom Horne
> wrote:
>
> >On Thursday, January 3, 2019 at 10:10:18 AM UTC-5, J.B. Wood wrote:
> >> Hello, all. As most portable consumer-grade AC generators don't have
> >> their grounds (frame and ground prongs on their mounted AC outlets)
> >> bonded to their neutrals, I was wondering what useful function having a
> >> 3-prong U-ground outlet on the genset performs (other than mating with
> >> appliance and extension cords). In a residence having the neutrals and
> >> green (grounding) wires connected together at the service entrance
> >> ensures that hot wire-to-exposed metal frame appliance faults (assuming
> >> appliance is using a 3-wire cord) will trip the appropriate panel
> >> breaker/fuse. This would not appear to be the case when using the
> >> portable generator. I'm only assuming that the generator is servicing
> >> 3-wire plugged-in appliances. I don't think it's a shock issue outdoors
> >> if a hot-to-ground fault in the appliance occurs, it may continue to
> >> function normally until it's subsequently plugged into a
> >> residential/commercial AC power outlet.
> >>
> >> Of course the equivalent action in the residence could be had by bonding
> >> the generator's neutral to its frame ground. Your time and comment is
> >> greatly appreciated. Sincerely,
> >>
> >> --
> >> J. B. Wood e-mail: ar...34@hotmail.com
> >
> >I came up short at your first assertion. In my 55 years of doing various
forms of local power production installs I don't remember finding one off the
floor portable generator were the neutral was not bonded to the frame.
>
> Honda inverters did not used to. Not sure about now but I think it
> makes the problem worse. Why would you create an extra path to kill
> someone if it did not exist before?
> (think ungrounded delta)
> They all have instructions to lift the ground if this is not going to
> SDS transfer equipment.
If there is no connection between the Neutral and ground then the voltage
relative to ground is unknown and more importantly a fault between the
energized conductor and ground does not create a shock hazard beyond a small
capacitive effect. If there is
no path back to the generator winding from the earth because the neutral point
of the winding is not connected to the earth then in one sense there is a
lower risk of an injurious electric shock.
I will admit that I never checked the bonding on the Honda Inverter Generators
because I have never had to use one that was connected to a building wiring
system were the National Electric Code has specific requirements about the
presence or absence of
the neutral bond that have to be matched to whether or not the transfer
mechanism transfers the neutral.
I find your experience with some of the Honda Inverter generators not having a
bonded neutral disconcerting because without that bonding jumper there is no
effective fault current pathway back to the source. I guess that it is
fortunate that I always
use a plug in Ground Fault Circuit Interrupter (GFCI) cord set between
Inverter generators or Inverters and the loads they supply. That is why we
have to use Full Sign Wave Inverters. Cord set GFCIs cannot tolerate a non
sinusoidal wave form without
tripping.
Now I'm going to have to check the Honda Inverter Generators to see if they
are bonded and correct that if they are not. Even if the GFCI protects the
user from an electrical injury that will not protect them from a startle
reaction injury; which are a
lot more common than most users are aware of; that may result from the brief
shock sensation they would experience while the GFCI is tripping.
In all cases I want the Over Current Protective Device (OCPD) or the GFCI to
have opened the circuit in response to any current fault prior to any living
thing experiencing any degree of shock.
--
Tom Horne
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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