ProSoundWeb Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: 1 [2]  All   Go Down

Author Topic: Just stumbled on a "new" Honda portable gennie...  (Read 13257 times)

Mike Sokol

  • Moderator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3361
  • Lead instructor for the No~Shock~Zone
    • No~Shock~Zone Electrical Safety
Re: Just stumbled on a "new" Honda portable gennie...
« Reply #10 on: April 15, 2014, 11:15:19 pm »

I think I have just incapacitated Mike S until he finishes reading it. sorry.   

Holy crap, that's a lot of links to study. But looks like some really good info. Interestingly, Honda tech support has been emailing me with questions about how GCFI's work in generators. It seems like EVERYBODY is a bit confused about this subject.

Logged
Mike Sokol
mike@noshockzone.org
www.NoShockZone.org

Stephen Swaffer

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 2384
Re: Just stumbled on a "new" Honda portable gennie...
« Reply #11 on: April 16, 2014, 01:46:18 am »

Reading the first article, I am confused as well.  If you define a leak as current that is not following its intended route, then it can not matter where the leak goes to.  It is simple math and physics.  If 2.50 amps is traveling to the load via the hot wire and only 2.4 amps is returning on the neutral wire, there is a difference in current and that is what the GFCI is looking for-simply a difference. 

Also. unless Kirchoff's law has been repealed, then the current leaving the generator winding-say 2.5 amps must equal the current returning to the generator winding.  If it is "leaking" and not returning via the neutral there MUST be a return path somewhere-or we are using really fuzzy physics.

The basic principle of all hot "bare hand" work is that if there is no return path, then no current will flow so no harm will come (and a GFCI will not trip-but if no damaging current is flowing it doesn't need to trip!).  I am not advocating doing that type of work unless you are trained and paid to do it-but there is plenty of that work done.  Physics doesn't work one way for one person/circumstance and another for someone else.

The "authority" author also appears to advocate running a generator without a neutral/ground bond with just a ground rod installed-this is very unsafe!  It also happens to be a code violation.
Logged
Steve Swaffer

TJ (Tom) Cornish

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 4284
  • St. Paul, MN
Re: Just stumbled on a "new" Honda portable gennie...
« Reply #12 on: April 16, 2014, 07:06:44 am »

Reading the first article, I am confused as well.  If you define a leak as current that is not following its intended route, then it can not matter where the leak goes to.  It is simple math and physics.  If 2.50 amps is traveling to the load via the hot wire and only 2.4 amps is returning on the neutral wire, there is a difference in current and that is what the GFCI is looking for-simply a difference. 

Also. unless Kirchoff's law has been repealed, then the current leaving the generator winding-say 2.5 amps must equal the current returning to the generator winding.  If it is "leaking" and not returning via the neutral there MUST be a return path somewhere-or we are using really fuzzy physics.

The basic principle of all hot "bare hand" work is that if there is no return path, then no current will flow so no harm will come (and a GFCI will not trip-but if no damaging current is flowing it doesn't need to trip!).  I am not advocating doing that type of work unless you are trained and paid to do it-but there is plenty of that work done.  Physics doesn't work one way for one person/circumstance and another for someone else.

The "authority" author also appears to advocate running a generator without a neutral/ground bond with just a ground rod installed-this is very unsafe!  It also happens to be a code violation.

This forum needs a "like" button. You are correct - GFCIs require a G->N bond to do anything.
Logged

Mike Sokol

  • Moderator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3361
  • Lead instructor for the No~Shock~Zone
    • No~Shock~Zone Electrical Safety
Re: Just stumbled on a "new" Honda portable gennie...
« Reply #13 on: April 16, 2014, 07:24:44 am »

Reading the first article, I am confused as well.  If you define a leak as current that is not following its intended route, then it can not matter where the leak goes to.  It is simple math and physics.  If 2.50 amps is traveling to the load via the hot wire and only 2.4 amps is returning on the neutral wire, there is a difference in current and that is what the GFCI is looking for-simply a difference. 


I'll have a little time to read all those links over the weekend, but here's one quick thought about GFCI operation. I think about GFCI circuits sort of like a balanced mic input looking for current rather than voltage. Just as a balanced XLR input is looking for a differential voltage, the GFCI sensor is looking for a differential current. It does this with a simple current transformer wrapped around the neutral and hot wiring. Common-mode currents are automatically cancelled inside the transformer, while differential currents create an output from the transformer that will trigger the trip circuit. Just like a XLR mic input can have interference from stray voltages that don't cancel, a GFCI can trigger from interference due to stray currents that don't sum to zero. More circuit tracing to do, but I'll think more about all this after reading those links and see what makes sense.     

And yes, without a Neutral-Ground bond in a generator, a GFCI won't have a fault current to sense since everything is floating. That's why I came up with my Neutral bonding kludge plug for RV generators with floating neutrals. Without that return path, pedestal voltage monitors won't work properly, and GFCI's in the RV itself won't trigger.

More to study...
« Last Edit: April 16, 2014, 07:32:27 am by Mike Sokol »
Logged
Mike Sokol
mike@noshockzone.org
www.NoShockZone.org

Frank DeWitt

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1010
    • LBP DI Box
Re: Just stumbled on a "new" Honda portable gennie...
« Reply #14 on: April 16, 2014, 11:04:37 am »

I think we are all coming together around a few facts.  For a GFCI to work there must be a Neutral-Ground bond (as Mike said)  There must be just one  Neutral-Ground bond.  One at the generator, one at the second generator, and one at the transfer panel is bad.

I think that if there is just one  Neutral-Ground bond then the GFCI must be after it in order to protect people. The reason. If the ground is after the GFCI then a person can supply a path to ground.  the current flows through the person, through the ground, and back into the Neutral at the  Neutral-Ground bond and back through the GFCI and the GFCI is happy, but the person in the current path is not.

Pictorially it is    Generator,  -  Neutral-Ground bond  -  GFCI   -   Load.

The Neutral-Ground bond  can be at the generator, or at the Distro box, or at the house,  But the order must be maintained, and there must be only one  Neutral-Ground bond, and it must be before the GFCI

If there are two  Neutral-Ground bonds with a GFCI between them, then the GFCI will trip.
If there are two  Neutral-Ground bonds before the GFCI everything still works but there are code / safety problems. 

If I am right, then
A  Neutral-Ground bonded generator with a GFCI can be used at a construction site, but not as a backup tied into a home transfer switch.
A non  Neutral-Ground bond generator could be connected to a box with a GFCI and a  Neutral-Ground bond and supply a construction site.
A non  Neutral-Ground bond generator could be connected to a house or a RV with there own ground and a GFCI after the ground
Two or more non Neutral-Ground bond inverter generators could be paralleled and there output connected to a to a box with a GFCI and a Neutral-Ground bond or to a RV or home with a  Neutral-Ground bond.

Of coarse there is no protection of any of the connections, plugs, ETC between the generator and the input to the GFCI  regardless of where it is located.  If you are standing between the generator and the distro or RV or house that has the GFCI and holding a bad extension cord going from the generator to the GFCI, you have a problem.  It does not mater if the Neutral-Ground bond is at the generator, or at the input to the GFCI

I think.
Logged
Not to Code

Stephen Swaffer

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 2384
Re: Just stumbled on a "new" Honda portable gennie...
« Reply #15 on: April 20, 2014, 04:25:36 pm »

I think that if there is just one  Neutral-Ground bond then the GFCI must be after it in order to protect people. The reason. If the ground is after the GFCI then a person can supply a path to ground.

Frank, practically speaking you are right.  Forgive me for splitting hairs, but I think this is one reason many get confused.  In the quoted section you used "bond" and "ground" to mean the same thing.

Bonding and grounding are two distinctly separate functions.  To be perhaps overly simplify, bonding is intentionally electrically connecting anything to a grounding electrode system-after the panel/distro this the function of most "grounds".  Grounding is creating a path to earth ground through a grounding electrode system (ie ground rods).

Bonding one side of the electrical generating system to the grounding electrode system creates a "neutral" or "grounded conductor" and   facilitates the operation of OPCDs and GFCIs. 

Grounding provides lightning protection and as well serves to minimize potential or voltage differences between metal equipment bonded to the grounding electrode and the earth.

In two of the earlier mentioned links, there is a claim that a ground rod provides a measure of safety on a floated neutral system.  This is not a claim I want to personally be the guinea pig to test.  Far better to bond the neutral to ground and be safe.

I would think the industry would respond if people asked for bonded neutral gennys-or even better for the av provider industry an easily convertible genny.  Virtually every breaker panel you buy is designed to be used either as a bonded neutral or with a separate neutral  and ground-and the selection is made in the field (OT but IMO they should be shipped bonded and make you change it-the opposite of what is usually done).  I do not see why a genny could not be designed to be convertible-and for the current configuration to be obvious at a glance-preferably right next to where connection to the genny is made.  Or perhaps provide only a twistlock output, and a built in "panel" that bonds the ground and neutral when plugged in, but gives the option to plug into the twistlock "unbonded" to feed a distro or parallel with another genny?

Also, to go out on a limb, in under 7 kW gennys the neutral and ground wires are the same size-so though I know there are technical concerns, if I am just running a few feet to a panel or distro, 2 neutral-ground bonds doesn't concern me near as much as not having a neutral-ground bond, so if I had to choose I would go with a bonded neutral genny.
Logged
Steve Swaffer

Frank DeWitt

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1010
    • LBP DI Box
Re: Just stumbled on a "new" Honda portable gennie...
« Reply #16 on: April 20, 2014, 06:43:08 pm »

Frank, practically speaking you are right.  Forgive me for splitting hairs, but I think this is one reason many get confused.  In the quoted section you used "bond" and "ground" to mean the same thing.


I am not sure what my writing seemed to say, but what I meant by "Bond" was connect together"  As in take the white wire, and the green wire and strip them and fasten them together.   Everywhere I used the term "Neutral-Ground bond" I meant, that place where the neutral wire or wires is electrically connected to the ground system (example, the frame of the generator, or a wire going to a ground rod, or the ground terminal in a disconnect. 

I agree that a generator with the neutral connected to the generator frame and to ground feeding a distro with it's neutral connected to it's ground wire running to a good ground would not bother me either.  But, If I wanted a GFCI I would need to place it after the ground in the distro.

I think.

I am not an expert on this, just thinking it through.  Education is good, and welcome.
Logged
Not to Code

ProSoundWeb Community

Re: Just stumbled on a "new" Honda portable gennie...
« Reply #16 on: April 20, 2014, 06:43:08 pm »


Pages: 1 [2]  All   Go Up
 



Page created in 0.044 seconds with 22 queries.