Gen sets MEP need advice

[jsdirtngravel.tyler@gmail]

What? Oh no. They're very reliable if you take care of them. Mine was dead on arrival so I'm having to pull out the main generator and replace it.

Oh ok ..

 

[jsdirtngravel.tyler@gmail]

1 last question and I'll leave everyone alone. (Grounding)
If the 804 is mounted on a surplus trailer,
Doesn't the trailer act as a ground? Or do you still have to throw a rod 8ft in the ground?
And or if your using it on concrete pavement?

 

[FarmingSmallKubota]

1 last question and I'll leave everyone alone. (Grounding)
If the 804 is mounted on a surplus trailer,
Doesn't the trailer act as a ground? Or do you still have to throw a rod 8ft in the ground?
And or if your using it on concrete pavement?

Ground, Ground,Ground

 

[Evvy Fesler]

1 last question and I'll leave everyone alone. (Grounding)
If the 804 is mounted on a surplus trailer,
Doesn't the trailer act as a ground? Or do you still have to throw a rod 8ft in the ground?
And or if your using it on concrete pavement?

The TM shows you how to do the grounding, but no, the trailer can be isolating. You want to bond it and the generator to earth.

 

[Guyfang]

1 last question and I'll leave everyone alone. (Grounding)
If the 804 is mounted on a surplus trailer,
Doesn't the trailer act as a ground? Or do you still have to throw a rod 8ft in the ground?
And or if your using it on concrete pavement?

Maybe you need to look at some TM's, if you want a MEP-804A or MEP-804B, and the various trailers that they can be mounted on. There are several, and grounding info is in them also. You need to know more about what can be done, before you pick out something.

 

[Coug]

If you look at any of the trailers these are mounted on, they will always have a lug on the frame somewhere for attaching a ground wire.

The point of grounding is to provide the electricity, if it's going places it isn't supposed to, a low resistance path to earth.

There are formulas for how much contact surface there needs to be for the ground rod/device in different types of dirt/soil/rocks. I know I was bitten more than once in the military because our field sites were mostly dry river beds that had really crappy grounding properties, and lazy people not driving ground rods in properly (which is almost impossible when you're talking about the ground being nothing but fist size gravel)

It isn't just the generator at that point, you'd get shocked when trying to climb up into a vehicle that was wired to the generator, 50-100 feet away from the generator. Usually the commo guys were the ones blamed for their radio setups not being properly grounded, but it was usually the generator's fault.

I got shocked a lot of times and survived without any issues that I know of, but all it takes is one time for the current to take the wrong path through your body and you can be dead.

 

[Evvy Fesler]

If you look at any of the trailers these are mounted on, they will always have a lug on the frame somewhere for attaching a ground wire.

The point of grounding is to provide the electricity, if it's going places it isn't supposed to, a low resistance path to earth.

There are formulas for how much contact surface there needs to be for the ground rod/device in different types of dirt/soil/rocks. I know I was bitten more than once in the military because our field sites were mostly dry river beds that had really crappy grounding properties, and lazy people not driving ground rods in properly (which is almost impossible when you're talking about the ground being nothing but fist size gravel)

It isn't just the generator at that point, you'd get shocked when trying to climb up into a vehicle that was wired to the generator, 50-100 feet away from the generator. Usually the commo guys were the ones blamed for their radio setups not being properly grounded, but it was usually the generator's fault.

I got shocked a lot of times and survived without any issues that I know of, but all it takes is one time for the current to take the wrong path through your body and you can be dead.

Please allow me add to what @Coug said. If you protect your downstream circuits with GFCI breakers or receptacles, they'll still work even if the earth ground isn't connected. They're a really good thing!

 

[Guyfang]

For years, we were told, that the gen set is bolted to the trailer, and that's bonding enough between the two. Then, in 2004, maybe 2005 came a directive from CECOM, (Communications and Electronics Command) that another wire was to be added from the generator Ground stud, to the Trailer ground stud. It seems that often the tie down bolts were not tight, or fuel and dirt were trapped between the gen set and trailer. Therefore, the proper contact between was missing and it was possible to get shocked. I never saw it happen, but I am just a repair guy, not a rocket scientist. Still, I rarely grabbed things with my closed hand. Always an open palm. I got bit a lot when I was young, but it was almost always my fault. Putting my knob dickers where they did not need to be.

 

[Evvy Fesler]

For years, we were told, that the gen set is bolted to the trailer, and that's bonding enough between the two. Then, in 2004, maybe 2005 came a directive from CECOM, (Communications and Electronics Command) that another wire was to be added from the generator Ground stud, to the Trailer ground stud. It seems that often the tie down bolts were not tight, or fuel and dirt were trapped between the gen set and trailer. Therefore, the proper contact between was missing and it was possible to get shocked. I never saw it happen, but I am just a repair guy, not a rocket scientist. Still, I rarely grabbed things with my closed hand. Always an open palm. I got bit a lot when I was young, but it was almost always my fault. Putting my knob dickers where they did not need to be.

Building on this... now that the trailer is bonded electrically, both the trailer and gen set need to be bonded to a grounding rod. If one were to follow the US NEC (National Electrical Code), there would be two grounding rods driven at least six feet apart unless one can demonstrate (with special equipment) that the resistance to earth is less than 4-ohms. So... a #4 or #6 wire from genset ground to trailer bolt to grounding rod(s). Be sure to use a direct burial clamp on the grounding rods. It may be interesting to note that if you can't drive the rods fully 8' into the ground because of rock or something else, you can dig two trenches 6' apart (min) and lay the grounding rods into the trenches. Don't ask me how deep. I can't remember, but solid soil would seem to be logical. Yep... driven full 8', which means that the typical 8' rod can't have any part above ground.

Note: Bonded means to connect in a very sturdy way both electrically and mechanically.

 

[Guyfang]

Two interesting documents for your reading pleasure.

 

[Guyfang]

And if that is not enough, go to page 37, of the TR 98-6. Lots of other reading suggestions.

 

[Poccur]

When grounding for long periods you should always try and think ahead. A week or two from now when you want to jump position that ground rod that was easy to drive when the ground is wet is set in concrete now the ground has dried out.
We used to drive them at 45 degrees (or so) then you can use the HMMWV to pull them out. Can't count how many times I have seen folk abandon the stuck rods, hammer it down flat to the earth and announce it lost.
Also, if you have a GET or DRASH trailer, drive the ground rod under the condensation drain of the air conditioner. Not only is it easier to pull it out weeks later, you keep the ground damp/wet for a good ground connection. Even in the desert it is amazing how much condensation you get once the tent is full up with folks talking.
If you are set up on concrete have a look around the edges of the lot. If you can find exposed rebar you can ground to that (like a Ufer ground).
My 2c
Cheers