MEP802A connection and distribution

[blhar15]

I have a nice MEP802A that will be trailer mounted for portable power. The manuals are kind of vague on power distribution and connections. I see there are military power distribution boxes available and various cables. I am trying to get a picture of how one of these would be wired up and to distribute power. For instance I have a couple of military shelters that have an input for genset power, but not sure how to get the correct cable for the shelter from their to the generator. It must go through some sort of distribution panel. I am assuming the distribution panel is hard wired to the genset, then standard type power cables with connectors go from the distribution panel to the shelter.

Any input would be helpful or pictures.

Thanks

 

[Ratch]

Behind the left door below the control panel, there are lugs. If you set the switch behind the control panel to single phase 120/240, you would connect your pigtail hot wires to L1 and L3, and I think L0 for neutral. There should be a data plate inside the door that says what lugs to use. Then ground is obviously ground.

There isn't really a distribution panel built on, you just get essentially the direct outputs of the gen. You would likely have to make one if you wanted one to be able to plug a cable into, or affix a receptacle of some sort (likely a 50a RV plug).

 

[DieselAddict]

I put a 50a plug on my MEP-003 and have a nice long cord that I can either plug into the house for backup or into a distribution box.

This isn't the cheapest way to go but it does get you most anything you need in a single package including the required GFI protection.

This is what I'm using for power distribution:
http://www.amazon.com/Coleman-Xtrem...814749&sr=8-3&keywords=power+distribution+box

Since you are using a MEP-802 you can use a 30a distribution box such as this one (a good bit less expensive):
http://www.amazon.com/CEP-Construct...ts-6503GU/dp/B000KL4I2K/ref=pd_bxgy_60_text_z

 

[blhar15]

The military must have had some way to distribute this power to a shelter. Here are a couple of pics of what I am talking about. My shelter has ports on it to plug in power. I am trying to figure out how to get from the wired connectors on my generator as mentioned the L1, L2, L3, L0 to the shelter itself.




Thanks

 

[schavez70]

dieselAddict I love that set up and I think I am going to go with the Coleman Cable 1970 Xtreme Box Straight Blade Portable Power Distributor...

but... my question is how do/did you connect your pigtail to the genset lugs.... and what is the right way to handle ground if the genset is on a trailer?!?!?! I have a Mep-802a and I have 80 acres and may need power at anyplace at anytime.... Do I have to drive a Grounding rod everytime I want to use the Genset out in the back 40 to farmer weld up a piece of equipment?

This post gives me hope!!!

Thanks in advance!!!

 

[DieselAddict]

I mounted a 50a receptacle in a damp locations box and wired it up to the lugs on the generator with 6ga wire. It is a 4 wire outlet and each terminal of the outlet is connected to its respective lug on the generator (L1, L3, L0, and ground).

I have my neutral and ground UN-bonded at the generator since it serves most of its duty as home standby. If I take it out in the field for portable power I bond the ground and neutral together then drive a ground rod connected to the ground lug at the generator. I've seen others report they put a switch between the neutral and ground for this purpose. I rather make the connection myself on the L0 lug. I can see it and know its connected. I'm just funny that way.

I also replaced the stock convenience outlet with a GFI outlet. That brought up the convenience outlet up to code.

 

[MtnSnow]

.. Do I have to drive a Grounding rod everytime I want to use the Genset out in the back 40 to farmer weld up a piece of equipment?

Short answer and usually incorrect is NO but not using one can be hazardous to your health. YES you should provide a grounding rod every time you are using the Genset in the back 40. Where it can get tricky is in how the Genset is being used IE: hooked up to a Home's power grid etc.

 

[Ratch]

The ground is for safety than anything else, but actual safety, not lawsuit-protection safety. It's very dangerous to run any power generator ungrounded because you, or anyone obliviously touching it, can become the ground if the equipment is shorted or miswired by the user.
I usually don't have a problem running them ungrounded with the lugs not wired or breaker/contactor off, but there is still chance it could have some sort of short that energizes the metal frame and fry's anyone touching it.

On the mep-80x series, there was an issue with some of the output wiring rubbing on the enclosure, allowing the conductor to short to the body. I forget if it was before or after the contactor; if before, there would be no automatic protection like a circuit breaker. Stopping the engine or killing the field would be the only way to de-energize it, something you can't do when all your muscles are spasming from electrocution.

 

[schavez70]

Thank So Much Everyone.... My water table is about 2 feet blow the surface.... would it be ok to drive just a 4 foot copper rod for the grounding rod?

 

[rustystud]

The ground is for safety than anything else, but actual safety, not lawsuit-protection safety. It's very dangerous to run any power generator ungrounded because you, or anyone obliviously touching it, can become the ground if the equipment is shorted or miswired by the user.
I usually don't have a problem running them ungrounded with the lugs not wired or breaker/contactor off, but there is still chance it could have some sort of short that energizes the metal frame and fry's anyone touching it.

On the mep-80x series, there was an issue with some of the output wiring rubbing on the enclosure, allowing the conductor to short to the body. I forget if it was before or after the contactor; if before, there would be no automatic protection like a circuit breaker. Stopping the engine or killing the field would be the only way to de-energize it, something you can't do when all your muscles are spasming from electrocution.

My MEP-002A had shorted the main power lead to the box. It never threw the circuit breaker just fried the internals a little until it stopped producing power.

 

[jimbo913]

I was wondering the same thing as I use my MEP to power a welder when not in home standby service. I dont think this is much different than a welder/generator setup on back of a pickup and after talking to some professional welders, they rarely run a ground and in many cases cant due to working on concrete or asphalt.
No doubt running a ground is the safer way to go but I question if it is really that huge a risk if you do not. I have used mine twice so far welding without driving a ground but I double checked that no wires were touching metal before I started and I was on gravel, not standing in water.

 

[DieselAddict]

Risk is one of those things that is in the eye of the beholder. Most safety codes are written to reduce risk to very low levels. Growing up on a farm we did things that would make OSHA freak out.

Anyway, maintaining risk at acceptable level in my opinion is a good thing to do. You need to decide what that level is for yourself. Since you can't see electricity this is an area where you can't always detect the risk until you get a shock. That is why you will see a good bit of over-mitigation of risk when it comes to electricity. Its silent, oderless, and colorless but certainly deadly.

Grounding and bonding (and GFI) is where you put a safety net out for electric shock. Many people think its the end-all for electricity but its not. Maintaining electrical equipment in good condition is MORE important than grounding. That means simple things like inspecting for frayed cords and damaged plugs/receptacles. It also means doing HIPOT testing on generators and motors from time to time. Those tests can identify a weak point in the insulation system before it creates a shock hazard.

I said all that to say this.. There are a number of layers of protection electrical systems employ. Grounding is kind of the last line of defense. If you make sure your overall electrical system is in proper order you reduce the chance of a shock whether you decide to drive a ground rod or not.

To address your comment about vehicle mounted electrical sources - Vehicle mounted sources do not require a ground rod when using cord operated equipment on or around the vehicle so long as the outlets for the corded equipment are on the vehicle. That would include welders or other portable electrical devices. Vehicle mounted sources must have the neutral and ground bonded and the ground of the source must be bonded to the chassis of the vehicle. If the welder is just sitting in the vehicle and its not properly bonded to the vehicle frame then that would be a code violation and would increase the risk of shock. Going by the code a welder sitting in the back of a pickup would likely require a ground rod if its ground wasn't electrically bonded to the vehicle per the NEC 250.34.

 

[jimbo913]

Thanks for the detailed explanation. You provided far more specific info than I have found on the net but I do have one question and that is, what benefit is there in grounding to the frame? Maybe a dumb question..

 

[DieselAddict]

Thanks for the detailed explanation. You provided far more specific info than I have found on the net but I do have one question and that is, what benefit is there in grounding to the frame? Maybe a dumb question..

Not a dumb question. My common sense answer is this.. Think about a scenario where you are sweaty from working and you lean over the back of the truck and adjusting something on the generator or welder. If the ground potential of the generator/welder is at a different level than the truck frame (meaning there is a voltage difference) when you reach over an touch the generator/welder while touching the vehicle with your sweaty and electrically conductive skin you have just become the wire in a circuit. Electricity will try to flow between the truck and the generator using YOU. It takes very little current to cause physical harm if its applied in the right place. The conductivity of your skin goes way up when you sweat. That is one of the parameters lie detectors measure with those little things they put on your fingers. Its called galvanic skin conductivity. You are much more susceptible to being seriously shocked when you are out working. Dry skin in contrast is a much better insulator so when you are laying around on the couch in the cool AC you aren't in as high a risk of being electrocuted.

You want to make sure the grounds of everything are all connected together so they are all at the same voltage potential. That way when you touch two adjacent metal objects you won't get a shock. Make sure the power has a better place to go than into you.

 

[schavez70]

Ok so I bought this receptacle http://www.amazon.com/gp/product/B005FVNGBE?psc=1&redirect=true&ref_=oh_aui_detailpage_o07_s00 and 100 Feet of 6-4 SOOW wire and a 8 foot grounding rod and Solid copper Grounding wire for it.... my RV sits almost 3/4 of a mile into the woods.... so there is no grid to connect to... Do I understand the following correctly?
1) Drive Grounding rod
2) Connect Grounding rod to LO and Ground (Basically binding LO and ground together)
3) Connect Black to L1, Red to L3, White to L0, and green to ground even though technically LO and ground are the same thing because they are bound together

If this is correct I think I am good to go... if it is not then How should this be wired?