Generator does not provide neutral ground bond.

unyalli
unyalli Solar Expert Posts: 121 ✭✭
in Caravan, Recreational Vehicle, and Marine Power Systems #1
Inverters with a neutral ground bond relay expect the AC input to provide this "bond" and release the internal "bond" when an AC input is detected. A shore power connection at a dock or camp ground should provide this "bond" but what to do if a generator does not?

-Jeff
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Comments

  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #2
    Re: Generator does not provide neutral ground bond.

    Use a relay powered by the generators output to create the bond, when the generator is off the bond is lifted.
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  • unyalli
    unyalli Solar Expert Posts: 121 ✭✭
    #3
    Re: Generator does not provide neutral ground bond.

    This turned out to be interesting. After checking three portable generator manufacturers documentation it seems standard to NOT bond the neutral and ground within the generator at least in inverter generators. I email one generator tech and the response was I could provide the bond my self if necessary without damaging the unit. He suggested I install a jumper on the back of one of the outlet receptacles to accomplish this. I then emailed Magnum and their tech responded it is very important the shore source provide this bond when using one of their inverters whether utility power or generator. Hmmmm?? Curious.

    - Jeff
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #4
    Re: Generator does not provide neutral ground bond.

    As you stated in your first post, a mobile Inverter ( UL458 ) makes a Internal Neutral / Ground when Inverting and lifts the bond when shore or generator is applied. The Inverters talked about on here are not always Mobile Inverters they are Off-Grid or backup ( UL1748 ) that do not create a bond when Inverting.

    What Magnum said could be right depending on what model they are talking about. It's tough with a RV because you really don't have a ground rod anyway. Most generators under 5 KW do not have a ground bond, but you can create one with a relay like I said, but without the ground hooked to a ground rod, it won't do much good. A Boat is different because you can use a grounding plate on the hull into the water.
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  • unyalli
    unyalli Solar Expert Posts: 121 ✭✭
    #5
    Re: Generator does not provide neutral ground bond.

    I may be a bit "off" but when I go "boondocking" or dry camping I have a nice copper alloy grounding rod 3 foot long I connect to the RV frame and my generators earth ground bolt. When I get around to installing a MSH3012M or MSH4024M I think I should open up my generators control panel and on the back side of the 30 amp RV receptacle install a jumper from the ground terminal to the neutral terminal. Now I can ground the generator only to my grounding rod and look like shore power to the inverter. I wonder if anyone else has considered this in the RV world.

    - Jeff
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #6
    Re: Generator does not provide neutral ground bond.
    unyalli wrote: »
    I may be a bit "off" but when I go "boondocking" or dry camping I have a nice copper alloy grounding rod 3 foot long I connect to the RV frame and my generators earth ground bolt. When I get around to installing a MSH3012M or MSH4024M I think I should open up my generators control panel and on the back side of the 30 amp RV receptacle install a jumper from the ground terminal to the neutral terminal. Now I can ground the generator only to my grounding rod and look like shore power to the inverter. I wonder if anyone else has considered this in the RV world.

    - Jeff
    Wow, your way ahead. All you have to do is make the bond. Inside the Generator panel is fine and it's permanent and not something you'll have to fiddle with each time. It doesn't matter where it is as long as it's just one.
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  • unyalli
    unyalli Solar Expert Posts: 121 ✭✭
    #7
    Re: Generator does not provide neutral ground bond.

    Thanks BlackCherry04

    - Jeff
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  • CraziFuzzy
    CraziFuzzy Registered Users Posts: 19 ✭
    #8
    Re: Generator does not provide neutral ground bond.

    OSHA actually requires portable generators to have the neutral bonded to the 'ground' (ground, here, being the frame of the generator). The frame of the generator, however, can only function as 'ground' when using the generator's outlets directly. If powering a structure (which I believe the RV should be treated as), the grounding to an actual ground rod needs to be done. This is done via a properly installed transfer switch when powering a building. Powering an RV falls through all regulatory cracks, as it is not technically an appliance plugged directly into the generator, nor is it a proper building.

    Just make sure all your outlets are GFI protected, and the bonding isn't all that important. (Just about all generator manufacturers recommend use of GFI's when using a generator to power anything - likely because of this grounding issue).

    Also of note. An RVIA approved transfer switch for an on-board generator has N-G bonding when switched to generator, and unbonds when switched to shore-power.

    http://www.noshockzone.org/generator-ground-neutral-bonding/
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #9
    Re: Generator does not provide neutral ground bond.

    OSHA may require it, but NEC doesn't and the majority of 'portable' generators have floating neutral.

    Don't put your faith in GFI either.
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  • CraziFuzzy
    CraziFuzzy Registered Users Posts: 19 ✭
    #10
    Re: Generator does not provide neutral ground bond.

    I'd contend that a GFI on an ungrounded system is far safer than non-GFI on a properly grounded system. A fault to ground on a properly grounded system will provide ground current up to the trip rating of the breaker. A fault on a GFI system, whether grounded/bonded or not will shut down at FAR less leakage current (<30mA).
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  • unyalli
    unyalli Solar Expert Posts: 121 ✭✭
    #11
    Re: Generator does not provide neutral ground bond.

    My RV has two 15 amp receptacle circuits. One is GFI with outlets near water and the one outside. The other circuit has outlets throughout the rig not near water. The microwave is on it's own 20 amp non-GFI circuit as is the roof mounted A/C and interestingly so is the dedicated laundry circuit. In all very little of my rig a 2014 Cougar SRX is GFI.
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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #12
    Re: Generator does not provide neutral ground bond.

    Grounding isn't as big of an issue when using a portable generator. The reason a good earth ground is important in a structure is because it is being fed by a utility, and all utilities bond their equipment to the earth. Therefore you can complete a circuit - through your body - if there is a fault in the structure. Instead the grounding system diverts this current.

    Even if your portable generator is sitting in water it will have a high resistance to earth since it isn't connected to a good ground rod. Creating a deadly circuit through your body back to the source - the portable generator - is nearly impossible due to its floating ground. Adding an extra layer of safety by using GFCIs can't hurt, but realistically it adds little extra safety while the RV is attached to the genset.

    I like the relay idea to create the N-G bond, but another idea, from Mike Sokol, is to use a "dummy" 15 amp plug which has the N-G bonded internally. Costs $3 and you can remove it if necessary, and it doesn't block the 30 amp outlet. In my case my Honda powers my house at times so I unplug the N-G dummy plug, but I plug it back in when I'm attached to the RV.

    I nearly killed my kids, and me, one summer when I hooked my RV up in the back yard and didn't know the ground pin was bad. They washed the camper in bathing suits, the ground was soaked, but they never made good contact with the frame so didn't feel a tingle. Later I grabbed the door handle - with rubber-soled shoes on - and got a good jolt. We were lucky.

    Soon after I started using a non-contact voltage tester every time I hook up the RV, after reading articles from Mike here: http://www.noshockzone.org/category/rv-safety/
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  • unyalli
    unyalli Solar Expert Posts: 121 ✭✭
    #13
    Re: Generator does not provide neutral ground bond.
    techntrek wrote: »
    another idea, from Mike Sokol, is to use a "dummy" 15 amp plug which has the N-G bonded internally. Costs $3 and you can remove it if necessary, and it doesn't block the 30 amp outlet. In my case my Honda powers my house at times so I unplug the N-G dummy plug, but I plug it back in when I'm attached to the RV.

    There we go. The kiss principal. Ya gotta love these forums. Thanks techntrek

    - Jeff
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  • DanS26
    DanS26 Solar Expert Posts: 269 ✭✭✭
    #14
    Re: Generator does not provide neutral ground bond.
    Cariboocoot wrote: »
    OSHA may require it, but NEC doesn't and the majority of 'portable' generators have floating neutral.

    Don't put your faith in GFI either.

    Here is a good list of generators indicating their factory bonding setup:

    http://www.generlink.com/CompatibleGenerator.pdf
    23.16kW Kyocera panels; 2 Fronius 7.5kW inverters; Nyle hot water; Steffes ETS; Great Lakes RO; Generac 10kW w/ATS, TED Pro System monitoring
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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #15
    Re: Generator does not provide neutral ground bond.
    unyalli wrote: »
    There we go. The kiss principal. Ya gotta love these forums. Thanks techntrek

    - Jeff

    Glad to share. Mike's site is a goldmine for RV safety. The biggest being the use of the NCVT. Buy one, they are cheap, and then use it every time!
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #16
    Re: Generator does not provide neutral ground bond.
    unyalli wrote: »
    There we go. The kiss principal. Ya gotta love these forums. Thanks techntrek

    - Jeff
    The only limitation there is that if a ground to neutral bond is required for proper operation of the system a purely temporary device like the dummy plug will not satisfy the NEC. Among other things the bond conductor will almost certainly be too small. (Including the wires to the receptacle as part of the bond, so it does not matter how big a conductor you put in the dummy plug.)
    If you and your insurance company do not mind that, then by all means go ahead (but I did not tell you to do that!)
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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #17
    Re: Generator does not provide neutral ground bond.
    inetdog wrote: »
    The only limitation there is that if a ground to neutral bond is required for proper operation of the system a purely temporary device like the dummy plug will not satisfy the NEC. Among other things the bond conductor will almost certainly be too small. (Including the wires to the receptacle as part of the bond, so it does not matter how big a conductor you put in the dummy plug.)
    If you and your insurance company do not mind that, then by all means go ahead (but I did not tell you to do that!)

    You are overthinking this. The power source is a portable generator so the NEC and the insurance company will be just fine with it - powering an RV or house. That is what they are made to do. A N-G bond usually isn't necessary for proper operation of anything with a portable genset, nor is it required for safety as I pointed out above. However, if you have an "intelligent" power monitor installed on your RV many of them will not connect the RV to the genset unless it detects a good N-G bond. That is when people usually pop up on camping forums wondering why their camper won't run from their generator even though it is fine when it is plugged in at the campground or at home.
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