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Honda generator question #25915
05/22/03 05:02 PM
05/22/03 05:02 PM
R
rmiell  Offline OP
Member
Joined: Nov 2000
Posts: 242
La Junta, Co. USA
I have a friend who has a Honda 3000w portable generator. He had it supplying power to a RV, and all things worked. He tried to use the microwave, and the GFCI on the generator tripped. Nothing else would trip this outlet.

He has tried using the microwave on other GFCI protected outlets (in his garage) and it works, with no problems.

He found he had an "open ground" on the generator outlet, using an outlet tester.

He has been in contact with a Honda repairman, who stated that the open ground was normal, as Honda does not connect the equipment ground wire to the outlet, due to problems with the outlet!!!

Has anyone experienced this same problem? Has anyone heard of this explaination before?

I have another friend with NEMA who I will contact about this, since I believe it is a hazard for Honda not to install the equipmentground wire to the outlet. I will let you know what happens.

Rick

Work Gear for Electricians and the Trades
Re: Honda generator question #25916
05/22/03 09:21 PM
05/22/03 09:21 PM
S
Sandro  Offline
Member
Joined: Dec 2001
Posts: 444
Stoney Creek, ON, Canada
I'm pretty sure most if not all Honda generators have a 'floating' ground. This is by design. Needless to say, this causes problems such as what you are having and also causes problems if you wish to connect a UPS. If you want to have some fun, hook up a digital meter and measure the voltage from neutral to ground, power to neutral, etc.

[This message has been edited by Sandro (edited 05-22-2003).]

Re: Honda generator question #25917
05/23/03 08:37 AM
05/23/03 08:37 AM
C
C-H  Offline
Member
Joined: Sep 2002
Posts: 1,497
Stockholm, Sweden
Some generators are indeed ungrounded. It works in the same way an isolation transformer does. (This is also known as an IT system.)

This means that the first fault to ground that appears does not have any dangerous result. It only grounds whatever wire that came into contact with the ground. The danger is a second fault on the other "leg". You could have two pieces of equipment with full mains voltage between the the cases.

Therefore, the ground wire is still very important: In case of a second fault, the current will flow between the two faults in the ground wire. This will of course the breaker. (It's a bit more complex if you have a large system, but this is just a small portable generator)

A grounded extension cord will protect you even if the socket at the generator lacks ground.

Honda must have done some trick to get a GFCI to work on a system of this type. Is there a ground rod?

Re: Honda generator question #25918
05/23/03 09:52 AM
05/23/03 09:52 AM
R
resqcapt19  Offline
Member
Joined: Nov 2000
Posts: 2,148
IL
C-H,
There is no "trick" required to make the GFCI work. If there is more than ~5 mA of leakage current the GFCI will open the circuit. If there is less than than, the GFCI will not trip, but that level of shock is not a serious hazard to most people.
250.34(C) requires that the neutral be bonded to the generator frame. 250.34(A) requires that the ground terminal of the receptacle be bonded to the generator frame.
Don



[This message has been edited by resqcapt19 (edited 05-23-2003).]


Don(resqcapt19)
Re: Honda generator question #25919
05/23/03 11:06 AM
05/23/03 11:06 AM
C
C-H  Offline
Member
Joined: Sep 2002
Posts: 1,497
Stockholm, Sweden
Don,

You are quoting NEC articles, but could it be that the NEC does not apply to generators of this type?

If the generator is isolated from ground and there is no ground connection at the outlet, there can be no leakage current.

If the neutral is bonded to the generator frame, then the ground terminal should also be bonded to the generator frame. If Honda has bonded the neutral but not the ground to the frame, I very much question the safety of this generator.

[This message has been edited by C-H (edited 05-23-2003).]

Re: Honda generator question #25920
05/23/03 12:01 PM
05/23/03 12:01 PM
R
resqcapt19  Offline
Member
Joined: Nov 2000
Posts: 2,148
IL
C-H,
If the NEC does not apply, then why does this section in the NEC exist???
Quote
250.34 Portable and Vehicle-Mounted Generators.
(A) Portable Generators. The frame of a portable generator shall not be required to be grounded and shall be permitted to serve as the grounding electrode for a system supplied by the generator under the following conditions:
(1) The generator supplies only equipment mounted on the generator, cord-and-plug-connected equipment through receptacles mounted on the generator, or both, and
(2) The non–current-carrying metal parts of equipment and the equipment grounding conductor terminals of the receptacles are bonded to the generator frame. ...


Don(resqcapt19)
Re: Honda generator question #25921
05/23/03 03:31 PM
05/23/03 03:31 PM
C
C-H  Offline
Member
Joined: Sep 2002
Posts: 1,497
Stockholm, Sweden
Don,
of course I can't argue with you. Sorry!

I was just trying to come up with an explanation as to how they could get away without having a ground and still have a safe and compliant system.

[This message has been edited by C-H (edited 05-23-2003).]

Re: Honda generator question #25922
05/23/03 09:00 PM
05/23/03 09:00 PM
E
Elzappr  Offline
Member
Joined: Dec 2001
Posts: 270
Oregon
Interesting thread! Since we are planning a building shut down soon, and are going to apply generator power to supply UPS fed computer equipment, I would very much like to hear more about why a non-bonded equipment ground from a generator might not work.

Re: Honda generator question #25923
05/24/03 05:17 AM
05/24/03 05:17 AM
S
Sandro  Offline
Member
Joined: Dec 2001
Posts: 444
Stoney Creek, ON, Canada
ElZapper.....do a search on the google discussion boards......type in 'Honda generator ground' or any other words along that lines and this subject has been heavily debated and discussed.

You need a special type of UPS to properly work with a generator.


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