MEP 016D Stand Alone Use

[s205designs]

Hi All,
I have what I think is a silly question. I'd like to hook up my generator for now as a stand alone unit in 120V single phase only. I'm starting small by wiring up a single NEMA 5-15 outlet to the lugs. My friend suggested I hook up Hot to L1, Neutral to L2, and GND to L0. After reading many posts and especially this one: http://www.steelsoldiers.com/auxiliary-equipment/92309-mep-016d-voltage-wiring.html

I'm thinking he's incorrect. My thought is to hook up L1 to hot and both ground and neutral to L2. Is this correct? I'm looking to use this in a portable setup for now. I don't know how realistic it would be to drive an 8 ft ground rod everywhere I go. If this is the case does bonding L2 to frame ground buy you anything?

Please tell me do I have this all wrong?

Also how do you shutdown your MEP 016D with a Yanmar, do you kill the fuel or shut down the governor. I read much about not letting the generator idle and i'm not entirely sure what exactly idle RPM is on the Yanmar. Killing the fuel the gen sputters for quite a while, killing the governor kills it faster, any thoughts?

Thanks,
Jonathan

 

[Isaac-1]

You don't have it all wrong, I have been looking at too many models lately to tell you if 120V 1 phase only is L1-L2 on the MEP-016d, but I think it is, what I can say for sure is your friend has it wrong, and the way you have it sounds right. As to your question about grounding in portable use, this is a complicated topic, the traditional answer was always drive a ground rod and bond the neutral to the frame. In recent years OSHA has issued guidelines that say portable generators with onboard outlets should not have a ground rod driven, this is contrary to many other approved practices, so take it for what it is. http://www.osha.gov/OshDoc/data.../grounding_port_generator.pdf

Sorry I can't get the link clickable, if you go to google and search osha portable generator grounding it should be the first pdf hit


think I have it now www.osha.gov/OshDoc/data_Hurricane_Facts/grounding_port_generator.pdf

Ike

 

[s205designs]

Ike,

Thanks for the reply. I am certain L1 & L2 are 120V as I did measure them with a DMM. I also measured the resistance between all of the terminals and all were open line with the exception of L1 & L2. I assume this means the generator is currently isolated from the frame.

With regards to the NEMA 5-15 connection, another possibility I was thinking could be to connect hot wire to L1, neutral wire to L2, and ground wire to chassis ground. But in this case I would have to bond chassis ground to L2 at the generator, is this also correct in thinking? Does having the frame grounded to L2 accomplish anything?

Thanks,
Jonathan

 

[Isaac-1]

I assume you also measured Lines to generator frame to see if anyone had added a bonding jumper (sometimes done in strange places, but most often on the front or back of the lugs)

Yes, having the frame grounded to L2 (often done inside the control box on the back of the lugs) does help if there is an internal short so the frame does not become live in reference to a tool you might be holding at the same time (think metal framed circular saw).

I am doing something similar on my MEP-016d for portable use, except I bought a surplus briggs and straton generator panel off ebay for about $25, it includes a pair of 5-15 15 amp outlets, a pair of 5-20 20 amp outlets and a twist lock 120/240 outlet (I don't remember if its 20 amp L14-20 or 30 amp L14-30) complete with push to reset breakers. They have plenty more, but forum rules do no allow linking to ebay.

Ike

 

[s205designs]

Ike,

Thank you so much for your help! I did check for connectivity between the Lugs and the grounding lug on the frame and all were open so I assume there are no jumpers in place.

If I were to add a bonding jumper from L2 to the frame inside of the panel, do you have any suggestions of where would be a suitable frame location? Also what size of wire would you recommend for this type of connection?

Thanks,
Jonathan

 

[ETN550]

The jumper should run to the lug on the bottom of the frame if you use the jumper.

Running stand alone without the frame grounded to earth is okay operationally speaking as far as the hardware is concerned. In that case bonding the neutral to the frame without the frame grounded is of no benefit
since when bonding to an ungrounded frame the neutral bond to frame is not completed to earth.

Grounding the frame will protect the operator if the gen or switch gear shorts to the frame and someone touches the frame while their feet are grounded.

Running a standalone system, it is advantageous to bond neutral to frame and frame to ground because some older metal cased tools or appliances may have their metal frames or cases bonded to the neutral in the tool. If the neutral is floating (not bonded to earth) then touching the metal case may shock one. This problem was fixed when all of the newer appliances and tools are "double insulated".

I run a lot of standalone without ground. Testing, for instance, and I run in the bed of my truck to power a camper while driving. However, I always have dry footwear and never operate in the rain or on a wet surface. For anything that is going to be around people or in one spot for a while I will ground the frame to a pipe or drive a rod if possible. The reality is nobody grounds small portable generators. I go to shows and events and there are hundreds upon hundreds of little gas generators running ungrounded. Not saying it's right.

 

[Isaac-1]

ETN550, there is a fault condition that you left out where there is benefit to bonding the frame to the L2 when in 120V single phase only mode that you left out:

Think about this, using your example of older neutral bonded to frame power too, lets say a circular saw:

Generator outputs 120V on L1 and L2 where L2 is wired to "neutral", no frame jumper, internal wiring L1 shorts to frame while generator is running, operator touches generator frame while holding the saw, ZAP

Now consider
Generator outputs 120V on L1 and L2 where L2 is wired to "neutral", This time frame jumper goes to L2, internal wiring L1 shorts to frame while generator is running, and you get a direct short tripping the output breaker, no chance for the saw to be part of the circuit.

Ike

 

[ETN550]

ETN550, there is a fault condition that you left out where there is benefit to bonding the frame to the L2 when in 120V single phase only mode that you left out:

Think about this, using your example of older neutral bonded to frame power too, lets say a circular saw:

Generator outputs 120V on L1 and L2 where L2 is wired to "neutral", no frame jumper, internal wiring L1 shorts to frame while generator is running, operator touches generator frame while holding the saw, ZAP

Now consider
Generator outputs 120V on L1 and L2 where L2 is wired to "neutral", This time frame jumper goes to L2, internal wiring L1 shorts to frame while generator is running, and you get a direct short tripping the output breaker, no chance for the saw to be part of the circuit.

Ike

Yes, excellent point. The generator does not know which lead is neutral, but for the old tools neutral will always be the case or housing, so bond neutral to frame and at least the breaker can handle one possible scenario. Good call.

 

[s205designs]

Ike, ETN,

Thanks for your insights, I'll probably end up running an external jumper from L2 to the Ground Lug on the frame. Does the gage of wire matter and is there a better internal location for this jumper?

ETN, i wanted to make sure I understand your statement:

"Running a standalone system, it is advantageous to bond neutral to frame and frame to ground because some older metal cased tools or appliances may have their metal frames or cases bonded to the neutral in the tool. If the neutral is floating (not bonded to earth) then touching the metal case may shock one. This problem was fixed when all of the newer appliances and tools are "double insulated"."

This would be because the generator is building a voltage relative to ground (since its floating) and then that voltage would discharge from neutral in older appliances through operator to ground, is that correct logic? The only way to prevent this is to either not use older tools or ground the generator. Correct?

Thanks,
Jonathan

 

[ETN550]

Yes, correct.

 

[Isaac-1]

The term ground gets confusing here, as there are many possible "ground paths" in case of a fault or multiple fault when dealing with a floating ground portable generator. In theory the generator would be isolated from the earth ground such as the case with an RV generator, the reality may be somewhat different either directly (metal frame sitting on damp earth, etc.) or indirectly through the attached wiring system. Please also note newer OSHA approved generators must have GFCI breakers/outlets which provide another safety net to the system.

Ike

p.s. I should probably note here how a GFCI works, to put it simply it measures amps on the hot and neutral connection if they don't balance it assumes any missing amps must have went to ground then trips

 

[s205designs]

Thanks again so much for taking the time to answer...

One more, then I think i'm done. If we say that having a tool with a neutral case (generator isolated) can deliver a shock to the operator due to voltages building up on a floating neutral... Wouldn't it be equally likely for the frame of an ungrounded generator to deliver the same shock if L2 and frame are tied together but the frame is not tied to earth? If this is the case wouldn't it be better to not have L2 tied to frame if you are running the generator stand alone, portable without a ground rod?


Thanks,
Jonathan

 

[Isaac-1]

There is more than one kind of shock, there is the potential of a static charge building up in reference to earth ground (the way lightning works on a grand scale) any time there is an insulator between the source and ground, then there is a shock from completing an electrical circuit which requires a path back to the source to complete the circuit, in this case the source is the other side of the generator winding.

The main advantage of bonding L2 to the frame is not the prevention of the circuit forming, but instead gives a path to trip the output breaker if L1 were to ground to the frame. Without the L2 to frame jumper then if L1 were to short to the frame then the frame would be hot waiting for the unsuspecting old neutral frame tool operator to touch to the frame.

Having said that there are scenarios where not having either L1 or L2 grounded to the frame might be safer, the classic example again being an old tool with neutral frame ground where someone has replaced or modified the plug so it can be inserted into the outlet with the polarity reversed, this would in effect make the frame hot, so that touching the L2 jumpered generator frame would then complete a circuit. However the same could be said of someone doing this in any conventional outlet where there is a metal conduit system or path to ground.

 

[s205designs]

Ike,

Thanks for the info and time spent on replies to my questions. Sounds like the best advice is to not use old tools

"I need to buy new tools, these older ones clearly are a safety hazard!"

Thanks,
Jonathan

 

[Jries]

What if any terminal should be grounded to the frame is running the generator in 240V single phase?

 

[ka25]

l1 =blk wire , l2=whie wire , if u using a 3 wire line the green or copper goes to goes to frame ground. on the other end, dont hookup the green or the copper to the panel. those things are ground sensitive. this how mine is and i used it every day for ten days.