I read your article, but have a question. You failed to mention how the generator would be connected to the trailer. It's my understanding that the only proper way to connect the generator would be through the AC hookup plug on the trailer. This way the ground wire from the generator would be connected to the frame of the trailer at the AC hookup plug.

There would be a problem if one wished to simultaneously connect the commercial AC and the power from the external generator at the same time. Two properly wired AC hookup plugs would be required. Most folks would simply unplug one and plug in the other, but there are cases where someone might simply want to run the wire from the generator into the trailer through a window or door without using the AC hookup plug. In my opinion, would be unsafe.

George,

I can't speak to all generators. but my Honda has a grounding terminal - IIRC its a small bolt/nut at the bottom of the generator. The generator ground terminal is connected to the frame of the generator, the metal non-current-carrying parts of the generator, and the ground terminals of each receptacle. That would be the place I would ground the generator and thus you would not have to worry about grounding an individual receptable.

Hope this helps.

Ruide

I just purchased a yamaha ef2000is and it has a Ground (Earth) terminal on the front panel of the generator. The manual states "When the electric device is earthed, always the generator must be earthed." WHAT DOES THIS MEAN?? Can I use the AC receptacles on the generator to power devices at home, camping, tail-gaiting, by just setting the unit on the ground/pavement and running the unit. Or, do I always have to run a ground line from the ground (earth terminal) to an 8 foot ground pole to prevent shock. I don't want to die, but it seems like a major inconvenience, to drive an 8 foot pole into the ground wherever I go... Please help.

Dbowlinir,

The comment that you found in your manual means that Yamaha is saying that if you were going to power something that was grounded then the generator should be grounded. Most of devices you would typically use for camping or tail gating are not themselves grounded. Plus just placing a generator on the ground does not meet the requirements for grounding.

What I shared in the blog are the US requirements - which in summary states that if you are plugging a device into the receptacle and the receptacle/metal parts are bonded to the frame then generator grounding is not required,

Now other countries may have different requirements and some manuals are written for a range of countries. If you are still worried I would encourage you to call or write Yamaha and ask about generator grounding.

Hope this helps.

Ruide

Your response certainly does help. I feel more comfortable about powering a space heater or a indoor lamp from the generator as is. However, can you give me some examples of grounded items that one might power with a generator, which in turn would necessitate grounding the generator?
Thanks,
Dave

Dave,

Actually, that is a question I would encourage you ask Yamaha (specifically for the US and for a portable generator) and see how they respond.

Let's back up a notch and look at the National Electrical Code 2005 edition. Article 250.114 has a list of equipment connected by cord and plug that must be grounded. They are:

3. In residential occupancies:

a. Refrigerators, freezers and air-conditioners
b. Clothes-washing, clothes-drying and dishwashing machines; information technology equipment; sump pumps, and electrical aquarium equipment
c. Hand-held motor-operated tools, stationary and fixed motor-operated tools, light industrial motor-tools
d. Motor operated appliances of the following types: Hedge clippers, lawn mowers, snow blowers, and wet scrubbers;
e. Portable head lamps

4. In other than residential occupancies:

Same as a, b, c, d, and e as above
f. Cord-and-plug-connected appliances used in damp or wet locations or by persons standing on the ground or on metal floors or working inside of metal tanks or boilers
g. Tools likely to be used in wet or conductive locations

Now let's assume your trailer has an AC and a fridge. According to the list above they should be grounded. And yes you will notice that they both have a three prong plugs. So far so good.

According to your manual, since your AC and fridge are required to be grounded then if you are going to plug them into the generator then - when ever you are camping you should first call the local utilities and request a survey of the area and once you are granted a permit pound an 8 foot grounded rod into the ground and connect it to your generator. Right?

Well that's not required by the NEC. Article 250.34 Generators-Portable and Vehicle-Mounted has an exemption. It states:

(A) Portable Generators. The frame of a portable generator is not required to be grounded to the earth if:

(1) The generator only supplies equipment or cord-and-plug-connected equipment through receptacles mounted on the generator, or both, and
(2) The metal parts of generator and the grounding terminals of the receptacles are bonded to the generator frame.

So in your case you are connecting the equipment to the receptacles and I'm assuming that your generator grounding terminals are bonded to the generator frame.

Hence, in this case the NEC does not require generator grounding and neither does OSHA. However, other countries may have different requirements and there is nothing stopping a company from making recommendations that go beyond law or in this case code.

So as I said before please call Yamaha for further guidance.

Ruide

Ruide,

I really appreciate the in depth and well-researched answers. Initially, I did call Yamaha and they were not very helpful. Basically, they referred me back to the manual. You've been the most help and I proceeded to fire up the generator, plugged in a lamp and an electric heater, and lived to tell about it! I will avoid plugging in larger appliances unless vital to survival, and will not stand on a wet or metallic surface while using any connected electrical devices. Thanks again for being so patient and helpful.

Sincerely,
Dave

Dave.

You are welcome and I'm glad I could help.

Take care of yourself and as always - Be safe.

Ruide