generator grounding...

Hi All,
 
 Merry Christmas,
 
I have a question for those who use generators on food trucks or on trailers. Do you ground your gen ? If so, what are you grounding it to ? I posted on a facebook group about my generator and these two guys have been battling it out over grounding a generator, one guy states he grounds to street poles if he can't drive a rod into the ground. Now i've never EVER seen anyone ground to a street pole, ONE for the simple fact that ppl are stupid and smart at the same time and would probably trip over the ground wire. I can't do that b/c my gen is on the left side of my truck. 
 
 What are you guys doing with your gens ?

I have a Honda EU3000is mounted to the generator rack on a Dreammaker XL-10 trailer. I don't have a ground wire. The owner's manual says "Before using the ground terminal, consult a qualified electrician, electrical inspector, or local agency having jurisdiction for local codes or ordinances that apply to the intended use of the generator.".
 
There are lots of safety warnings throughout the manual regarding everything from not operating inside a building to not filling it with gas when it hot and running. Nothing about it having to be grounded in order to be safe.

always thought it was grounded thru the plug to the ground on the trailer elec. box.

OK ...  from the top of my head  ... I'm not doing research on this..
 
You need to know what 'grounding' does:  it returns stray current to the generator producing the electrical power.    In the residential & commercial (world) the power company s ground their huge power plants to the earth; therefore current is returned by a ground wire or by the earth to the power plant to complete a circuit.
 
Now a generator set in the back of a truck or mounted on a trailer with rubber tires will not complete a circuit when grounded to a street pole or the ground wire on the pole.   The generator set on your cart or trailer is isolated from an earth ground by the rubber tires as well as the cart or trailer itself.
 
The circuits from the genset already have a ground wire. For most cases and uses this should be sufficient.  If the gen set is installed as a permanent setup, you might want to connect the ground terminal to the frame of your trailer; and then connect the ground bar of the power panel to the trailer frame.  There are 2 ground bars in modern panels; One is for the wiring neutral/ground; the other is for earth ground.  The earth ground bar is the one to connect to the trailer frame and the circuit of which prevents a short circuiting appliance from shocking you.  The earth/trailer ground is the 3rd (green) wire in 3 wire circuits or cords
 
Now it also stands to reason that if there is no earth/trailer ground (gen sets only), then a short circuiting appliance cannot electrocute you;  (????) there is no complete circuit.   I have to check what conditions this may not be true (???).      ... This is certainly not true for power company supplied electricity; there is ALWAYS an earth ground.

My electrician installed a four wire system in my trailer but I haven't a clue why. He just said that's what you have to do for a truck or trailer to be grounded.

Dr of BBQ


My electrician installed a four wire system in my trailer but I haven't a clue why. He just said that's what you have to do for a truck or trailer to be grounded.

 
The four wires your talking about sounds like what is used to plug the trailer into the tow car's lighting system. Did he wire up the lights for your trailer and plugin?

LMAO No that's not what I'm talking about. God LOL,
I'm talking about a 30 or 50 amp wire system like this.
 

Dr
what you picture is a 4 wire service for 120/240 volts. 

• 2 ea 120 volt hot wires
• 1 ea neutral wire (this one connects on the power company side back to ground)
• 1 ea ground to earth wire; U-shaped prong at the top   This one connects to earth ground at the service panel.   This being a trailer, it is not in use unless you connect to a ground rod or ground wire on the power pole.       With a shore power connection to a service panel this would be in use;   but a connection to a gen set, it may not be used depending on how the pigtail is made and connects to the generator.    This wire only carries current if a hot lead shorts to ground.

Alright I understand the ground runs from my electrical system in the trailer back to the power pole where it is grounded. So that's how that system works. So now my build will be set up to run shore power and from a generator also.And I understand I need a switch and breaker panel to go from one to the other.
 
Ok so here is what my generator out put (10,000 watt surge 8000 watt continuous  220 volt 31 amp) takes so how should it be wired? And where is the ground wire or is there a ground wire that runs through the system?

Your food trailers should be wired up like an RV. Any power box on a pole for an event or at your home SHOULD be wired up just like a box in a campground.
 
They are different than regular house systems and many pro electricians will wire them up wrong. The grounding messes with them. That is the part they don't get.
 
Read and learn....
http://www.rvforum.net/joomla/index.php?option=com_content&view=article&id=163:50-amp-shore-power&catid=37:electrical-power-systems-and-hookups
 
http://www.dasplace.net/
 
http://www.bobhatch.com/electricStuff/whats_it_mean.htm

LOL, gotcha (30 OR 50 amp) Dr of BBQ.

On the service panel of your trailer/truck, the ground bar (equipment ground) should be grounded the the metal frame of the trailer/truck; and the ground wire (green) of the shore line connected to the ground bar.   Then the ground (green) wire from the shore line or generator will work correctly.
 
In a permeate installation (residential/commercial) the ground bar may be connected to the ground rod or both building's metal frame & ground rod.
 
Ok ... what happens is If a power wire (120 volts) shorts to the metal frame of the trailer and the frame is grounded, the breaker will pop, killing the power;  ... if the frame is not grounded, then the circuit is open waiting for someone to touch metal and an electrical appliance which is ground by wiring to compete the circuit.   That will rune your day; and we will very likely need to know where to send flowers and condolences.
 
So if the service panel in the trailer or truck is properly wired & grounded, then there is little concern for connection of shore power or generator sets as long as these are connected by manufacture's instructions.

When we did the Ohio State Fair they had us drive a ground rod and clamp it to the trailer frame with a ground wire. The Tennessee State Fair did not require the ground rod.

You need to be testing what you plug your trailers into. There should be no reason to ground your trailer if the power pole is wire correctly. If the power pole is wired incorrectly, you are risking damaging all your electrical equipment as well as yourself. You can buy a simple inexpensive tester that will tell you if a ground in not connected correctly (if at all). Just plug it into a plug adapter and it will still work. this is what I use for the various campgrounds we stay in. You would be amazed at how many "weekend electricians" will rewire a campground pole (mostly in public campgrounds) because they have screwed up the wiring in their RV so badly, it won't operate on a correctly wired pole. They truly think they are "fixing" it..
 

$8 one shown  also has one a little cheaper at $4
Mine is older and yellow. Does the same thing. It will show the most common problems. I plug mine into these adapters... (not, this has kept us out of only three campsites in 10 years  and possibly saved the lives of one family... their site was miswired and they were getting a "tingle"... then it rained)
15 mp to 30 amp. I can test a 30 amp plug which is what the bus takes. The tester generally stays in this adapter. But I also need the tester to test the 15/20 amp receptacles because we plug the food cart into the 20 amp plugs to charge the battery or run the 60 watt bulb we stick in the cart to prevent the water from freezing. My heat taped winter hose also needs to be plugged into a 15/20 amp plug. It doesn't need an adapter for that.
I can also plug my 30 amp RV into a 50 amp service. This is what we use for mobile home parks and some 50 amp only campground sites. The 20 to 30 amp adapter shown above will plug into the 30 amp plug of this and I can test the 50 amp outlet.
 
Like on an RV, when you plug your trailer into the correctly wired power pole, you are using their grounding.
 
But what do I know. The Class C we were living in has a ground fault in the panel box and we were plugging into ground fault protected power poles (correctly wired).  The RV ground fault would trip before the power pole. I've been told that won't work... but it does on our setup. And I'm not the only one with a working setup like that.

Lorna, is absolutely dead on
 
"You would be amazed at how many "weekend electricians" will rewire a campground pole (mostly in public campgrounds) because they have screwed up the wiring in their RV.
 
We  drove for 3 hours to vend at a fall color drive and I plugged into a box and got 440 instead of 220. The lady that ran the event of course didn't know anything and they had no electrician on hand. Ended up spending 8 hours trying to get the mess straightened out. Never sold a thing on the biggest day of the weekend. Left early the next day and the weekend cost me a ton for travel, staff, hotel rooms, and entry fees. I never went back.
 

I'm assuming that the 440 volts was across the two hot legs (220+220=440).     .... ??? ... the hot legs should have been 120 volts each.  Did you figure out what was done to the panel or service box?   Someone installed a transformer and forgot to remove it, maybe???????

edwmax


I'm assuming that the 440 volts was across the two hot legs (220+220=440).     .... ??? ... the hot legs should have been 120 volts each.  Did you figure out what was done to the panel or service box?   Someone installed a transformer and forgot to remove it, maybe???????

 
To this day I'm not sure. The town was so small they had no electrician on duty for the event, and a guy from the local hardware store and another from the local water department tried to help. It really sucked, back then, cost a bunch of money out of pocket and no chance to make it back. But you know it's a live and learn business.