Why do MEPs require ground rod and RV/portables do not?

[445gsdss]

I've recently purchased a 002 and a 16d. I am waiting on the electrician to come out to wire the 002 into the house panel. (3-4 weeks) In the mean time I'd like to start the MEP-002 up (been about a month since I bought it from the PO and it's sitting in garage on a trailer) but I don't have a ground rod or want to go to the trouble of installing one for just a couple weeks. I don't plan on using generator, I just want to start it regularly.


Regarding the 16d, I just purchased it from an GL auction. I would like use it as a portable power source.


I'm not an electrical wiz, so in both instances, I don't understand the ground rod requirement. I have an existing 4kw RV generator that is on a trailer that I have used for hundreds of hours with no external ground (not that this was correct) and a portable 7kw gas generator that I've also not grounded. Could someone explain to me why the military gensets need grounding but the civilian do not? Or is it a misconception that the civilian versions (RV and portable) don't need to be grounded and should be?


Can I start either without running the chance of killing myself without the ground rod? Again, I'd like to cycle the 002 and will need to go through the initial tuning and turn up with the 16d. The 002 has a digital gauge plugged into the convenience outlet for tuning RPM but nothing with be wired to the lugs. If a load needs to put on the genset I can plug a space heater into the outlet as well.


Thanks for any help!

 

[Mercunimog404]

The military is overly redundant.

 

[tigger]

It will run without it!

 

[Suprman]

The military grounds everything. It is for safety. It helps prevent interference. Clamp a wire onto a pipe in your house and you will be grounded.

 

[glassk]

Ground rods (grounding electrodes) are only required if the generator is a separately derived system.as Suprman mentions , using the house ground will also will avoid potential step voltages ,

 

[dependable]

It is pretty easy and cheep to buy a 5/8 galv grounding rod and a clamp. You don't have to drive it in that deep or permanent, but it is good to ground any gen set when using unless it is grounded to house with 4 wires. Why not have a ground rod installed near where you work on your generators?

You probably won't kill yourself without a ground, but why take the chance? Problems are most likely to occur when generators are getting worked on and tested. All you have to do is trip over the neutral when you are doing a load test...

 

[glassk]

When fault current is conducted to ground, the immediate result should trip a breaker or blow a fuse, effectively shutting off the power.

 

[dependable]

'Should' is the operative word here. Anyway, not sure if you agree with me or not, but when I play with my gen sets, I like having a ground rod in place, makes me feel grown up and responsible.

 

[Coffey1]

Also just like a motor winding can short to ground and not trip anything. I found out the hard way when I worked maintenance in a plant and layed my hand on a motor to see if it was running hot and got the shock of my life.I do believe if I had been grounded better would not be here to tell you.

 

[tennmogger]

I recall an earlier thread about wiring generators into houses and the problem was that the generators had no neutral coming out of the generator with the 220 v. 220 v 'works' to drive it's load just fine with no neutral. BUT if there's no neutral carried between the components of the system (generator, house/trailer/shelter, etc) then there the chance of any leakage to frames or chassis', to make the component hot with respect to earth. That would be very bad news for anyone touching the component. That's why grounds are required, not for running the load, but to protect the human.

 

[Suprman]

I remember we had a humvee set up outside with an aux power supply so the batteries would not go dead. There was com wire run into a building and a few field phones were wired up. The first guy to pick up the field phone set up in the building ended up on his ass from a big shock. Turned out the aux power supply had a bad ground and everything ended up with a 120v potential because of it.

 

[Isaac-1]

Read the owners manuals on those portable generators, chances are if they were built more than 3 or 4 years ago when OSHA changed their rules to no longer require ground rods on portable generators with cord connected hand tools, the manuals likely include a section on driving a ground rod, just no one ever does it.

 

[Suprman]

It's one thing to run a power tool off a generator, most newer power tools are well insulated. If you are connecting it to your house electrical system it needs to be grounded with a common ground preferred for this type of use. Without a ground you can get an electrical potential where you don't want or expect it to be. 120 volts at 50 amps can easily kill. In the military it's safety first and everything is safety oriented. If you want to use the equipment then you should do it properly. It falls under the same principle of knowing airbrake safety before getting behind the wheel of a 5ton.

 

[glassk]

. You don't have to drive it in that deep or permanent,

Ground rods shall be driven into the ground so that one end of the ground rod is at a minimum depth of 8 feet below the surface of the ground, soil conditions and moisture also PLAY into it, I'll leave this Thread for the Grown Up's , I Wonder what the TM say about Grounding,.

 

[Flingarrows]

Ground rods shall be driven into the ground so that one end of the ground rod is at a minimum depth of 8 feet below the surface of the ground, soil conditions and moisture also PLAY into it, I'll leave this Thread for the Grown Up's , I Wonder what the TM say about Grounding,.

x2. Depending on the moisture content of the soil, you may need a ground grid - several rods spaced apart, and bonded together. The TM should explain the procedure and how to measure the ground potential

 

[swbradley1]

If you are connecting the generator close to the lines coming in where the meter bar is located there is a good chance you already have a rather large grounding rod already installed. Just tie to it.

As for problems I do understand leakage and "hot" chassis from way back. I'm not fond of either...