Generator Grounding

K2

OK I'm starting to almost understand grounding and bonding. Maybe. But if I have a generator on the back of my pickup what do i need to know about grounding it. Will I get current to earth ground?? Just curious.

Speedy Petey

You need to make sure the neutral is bonded to the frame or the genset, and to the vehicle frame.

Here is the applicable section:

(B) Vehicle-Mounted Generators The frame of a vehicle shall not be required to be connected to a grounding electrode as defined in 250.52 for a system supplied by a generator located on this vehicle under the following conditions:
(1) The frame of the generator is bonded to the vehicle frame, and
(2) The generator supplies only equipment located on the vehicle or cord-and-plug-connected equipment through receptacles mounted on the vehicle, or both equipment located on the vehicle and cord-and-plug-connected equipment through receptacles mounted on the vehicle or on the generator, and
(3) The non–current-carrying metal parts of equipment and the equipment grounding conductor terminals of the receptacles are bonded to the generator frame.

HANDBOOK COMMENTARY:
Vehicle-mounted generators that provide a neutral conductor and are installed as separately derived systems supplying equipment and receptacles on the vehicle are required to have the neutral conductor bonded to the generator frame and to the vehicle frame. The non–current-carrying parts of the equipment must be bonded to the generator frame.

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mdshunk

You may notice that many of your better generators do have a lug bolted on them someplace to run that bonding jumper to some metal part on the truck.

K2

Thanks. So if I'm ankle deep in mud and touch the hot do I get a buzz??

Teetorbilt

I believe that this would only apply to vehicle MOUNTED units. A portable unit is usually on rubber feet and most vehicles are mounted on rubber tires. As such both are isolated.

Rob, I would advise against becoming a ground path in any situation.

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You can't solve you're problems with the same level of thinking that created the problems.

Albert Einstein

K2

Hmm, no answer. That usually means I should know the answer. But I didn't get pistol whipped so it probably wasn't too dumb of a question. I'll have to go out and make some mud tomorrow.

I'll try to use a meter Teetor. I'm guessing zero.

Teetorbilt

Use the meter! Not you! You will get zapped! Electricity doesn't care where the ground comes from or how it gets there. Be careful and hope that md chimes in.

Most of my AC experience involves yachts.

__________________
You can't solve you're problems with the same level of thinking that created the problems.

Albert Einstein

mdshunk

I don't see how you could get shocked standing in the mud if a tool was shorted out, unless the generator was in that same mud with you. You need a conductive path back to the generator for current to flow, and the earth sucks as a conductor except at very, very high voltages. If you and the generator were both in a mudpuddle, then you might get shocked if you were using a bad cord or faulty tool. If your generator was 100' away, no way in hell. Besides, jobsite gensets all have GFCI's now anyhow, and if they don't, OSHA's making you use a GFCI cordset. The reason that you have to bond a generator sitting on a truck to the truck is so that you have an "equipotential plane", which is another thing altogether that has less to do with clearing faults.

Don't try this... but you can grab a bare hot wire supplied by a generator while you're standing on the ground and you won't get shocked. If you were holding that hot wire and walked up to the generator and touched its frame, then you'd get the **** shocked out of you.

Following Teetor's advice is most prudent, because it will keep you safe in any case, and frees you from having to puzzle on the science.

K2

I'm unpuzzled for the moment. Thank you.

Teetor wants to go 400 miles per hour and worries about me being safe. Perspective.