Does a portable generator need to be grounded?

[Rickey]

Let's look at this objectively:

If you touch the hot wire from a generator that is grounded
to earth (including neutral) while standing in water; you will be shocked and possibly killed!

Under these circumstances there is a completed electrical circuit from the generator to ground through your wet feet back to the hot side of the generator!

If you do the same with an ungrounded generator; the circuit is not completed.

The above assumes there are no other connections to the generators power circuit.

Bottom line:

Avoid completing electrical circuits through your body.

Rickey.

 

[tom slick]

To put it all together into something that makes sense and not fragmented:

"Does a portable generator need to be grounded?"

NEC article 250 addresses grounding and bonding.

250.34
"(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."

That answers the question but doesn't tell you why the manual says to ground the generator.

Reason for grounding
250.4.A.1
"Grounded electrical systems (transformer, generators, etc) must be connected to the earth for the purpose of limiting the voltage imposed by lightning, line surges, or unintentional contact with higher voltage lines, by shunting the energy to the earth."

The NEC states voltage under 600v is not effectively cleared by Earth.

Unless you touch a high voltage line, or lightening strikes you while running the trimmer, you will not come into contact with voltage high enough to make an Earth ground (ground rod) an effective safety device.
Also, there is so much resistance in an Earth grounding circuit that it doesn't allow enough current to flow to trip a circuit breaker but it does allow enough current to kill you.

That's informative but why does the manual say to ground the generator but the NEC says I don't need to? (Sometimes you have to ask twice)

It's the way you are using the generator; just extension cords and small power tools. If you were to plug that generator into your house then it would need to be grounded. Your house or the power lines connected to it could be struck by lighting or experience a power surge. That would be sufficient voltage to make the protection from an Earth ground circuit effective.

 

[gman2304]

What would be the best way to ground one of these small HF generators if you were using it as a portable power source in your yard? Thanks, G-man

 

[Warstud]

Originally Posted By: tom slick
The main reason for grounding is lightning protection.


It needs to be grounded in case it falls into the bathtub.

 

[eljefino]

It's also plausible that the NEC only applies to stuff that can burn down your house through the wiring installed within. If you're using the generator with extension cords outside, from their point of view, helping insurance companies avoid fires, they don't care.