Is this portable generator hook-up OK?

Discussion in 'Electrical Forum discussion & Blog' started by mbwayne, Oct 20, 2011.

  1. mbwayne

    mbwayne New Member

    Messages:
    3
    Location:
    Pennsylvania
    I'm looking for some middle ground between running extension cords to my portable generator vs. a transfer switch. Please let me know if you see any downside to this hookup: (1) 15-foot L14-30 cable from 7500W generator to 30A outside inlet box; => (2) 50' 10 gauge/4 conductor cable to female L14-30R receptacle (or box mount the female receptacle); => (3) Y-adapter with male L14-30R plug that splits into 2 120V 20A receptacles. The main things I want to power (2 sump pumps and a fridge) are within 20 feet of each other in the basement, so there would be minimal need for extension cords to plug into the Y-adapter.

    If I decide to install a transfer switch in the future, I would already have the 50' run to the electrical panel, so the only wasted components would be the female L14-30R and the Y-adapter.

    Two questions: (a) With this set-up, will I need to ground the generator outside?; (b) Is there any way to skip the Y-adapter and simply create 2 120V receptacles from the 10/4 cable? (I read something about not wanting to share the neutral, but not sure how the y-adapter wires this safely).

    Thanks for your help.
  2. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,570
    Location:
    North Carolina
    No you don’t need a ground rod for the generator and all the rest needs to be scraped and a new and better idea.
    Use enough cords to where you can use 120 volts to supply 120 volt appliances.
  3. Gary in NJ

    Gary in NJ New Member

    Messages:
    90
    Location:
    NJ
    I would give serious consideration to a sub panel with a transfer switch. Standing in puddles in the the middle of a rain storm is no time to jury-rig a generator.
  4. Chad Schloss

    Chad Schloss Member

    Messages:
    330
    Location:
    USA
    i really don't know why people think that hooking up a generator in the rain or snow or sunshine for that matter is all that difficult or dangerous. he is talking about using a twistlock connection, which is probably the best connection you can get on something like that.. explain what is so dangerous, standing in a puddle or not, how inserting a plug into a socket and twisting it, then firing up the gen set will injure / kill you, please?
    Last edited: Oct 20, 2011
  5. drick

    drick In the Trades

    Messages:
    392
    Well for one, it is bad for the generator to operate it in rain. The generator has electronics in it that are possibly not water resistant - GFIs, load sensors, idle controls, hour meters, inverters, etc. Its also not so great for the electrical portions of the generator either. Personally I would never operate my generator in the rain, however I've seen many people right in my neighborhood do it. One of my neighbors thought he would be smart and keep the generator up close to the house, under the roof overhang, to help keep it dry. Too bad he faced the generator exhaust toward the house. He was lucky, the house did not catch fire, but he melted a good sized section of siding. I think that counts as a very close call as to how you can be injured or killed when you operate a generator in the rain.

    Two, you are however betting your life on something most likely made in China. They don't have the best QA departments over there. If you come into contact with any sort of fault and you are wet the odds of the shock killing you go way up.

    Also, it is well documented that homeowners DO kill themselves with generators. They use them during a storm and they are already worried about the food in the fridge, pipes freezing, basements flooding etc, so they rush and they don't think through everything they are doing. They use undersized extension cords to connect to heaters, they run the generator in the garage to keep it dry or not bother the neighbors at night, they refuel hot generators because their basement will flood if the sump pumps don't have power, they run extension cords up stairways - the list goes on. After every major storm causing substantial power outages in my area there is always a report of a homeowner killing themselves or the whole family with a generator.

    Personally I don't advocate running your house off extension cords. It always starts off as "I just need it for the fridge/ furnace". But after a couple days of no power there are extension cords to the lights downstairs, the lights upstairs, the TV, the microwave, etc. I think a transfer switch is the only way to go.

    -rick
  6. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,570
    Location:
    North Carolina
    Dirck makes some good points and none of these self-contained generators are listed for use in during inclement weather.

    Then we have the listing issues

    ENGINE GENERATORS FOR PORTABLE
    USE (FTCN)
    GENERAL
    This category covers internal-combustion-engine-driven generators rated 15 kW or less, 250 V or less, which are provided only with receptacle outlets for the ac output circuits. The generators may incorporate alternating or direct-current generator sections for supplying energy to battery charging circuits.
    When a portable generator is used to supply a building or structure wiring system:
    1. The generator is considered a separately derived system in accordance with ANSI/NFPA 70, ‘‘National Electrical Code’’ (NEC).
    2. The generator is intended to be connected through permanently installed Listed transfer equipment that switches all conductors other than the equipment grounding conductor.
    3. The frame of a Listed generator is connected to the equipment grounding conductor and the grounded (neutral) conductor of the generator. When properly connected to a premises or structure wiring system, the portable generator will be connected to the premises or structure grounding electrode for its ground reference.
    4. Portable generators used other than to power building or structure wiring systems

    Cords is the only other way it can be done but it cannot have duplex receptacles on the 30 amp plug.

    On a side note is the type of current one of these small generators deliver. It is not very clean and some electronics are very unforgiving when it comes to the signal they receive from these generators.


    Sump pumps and a light plugged in is about all one of these small generators will take. They are not designed to have a lot plugged into them.
  7. leejosepho

    leejosepho DIY scratch-pad engineer

    Maybe someone has already said this and I have missed it, or maybe I am wrong, but as I understand things, it is *never* okay to have a generator connected unless there is something mechanical making it absolutely impossible for any power from the generator to ever get/go back out to the incoming service line for the duration of the generator's connection.
  8. mbwayne

    mbwayne New Member

    Messages:
    3
    Location:
    Pennsylvania
    Thanks for all the great comments. I've gotten quotes to install a 10-circuit transfer switch with the same run described above, and they've ranged $1600-$1850 for materials and labor. Just can't swing that right now for a device that may only be used once per year.

    Is the Y cord splitter the main problem? I was looking at the GenTran Model #RJB10403Y. Is this not a safe/approved device? If so, it just seems like all I'm doing is providing a 10/4 extension from the generator to the Y-splitter, which seems much safer and quicker to set up than running extension cords from the generator.

    Thanks again.
  9. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,570
    Location:
    North Carolina
    The 10 circuit transfer switch is no longer an approved deal; see my post above from UL

    The splitter is protected at 30 amps and the duplex can be protected by no more than 20 amps and be compliant and safe.

    We must be aware that just because something will work in no way means it is safe.

    The only safe way to use one of those small generators is with a drop cord from the receptacle to the equipment being served or to connect it to a transfer switch that also switches the neutral.
  10. Gary in NJ

    Gary in NJ New Member

    Messages:
    90
    Location:
    NJ
    My was installed for $500 in labor. I purchased the material myself, it's been a while but I'm gonna say less then $200 out of pocket. On my sub-panel I have the following circuits:

    Well Pump
    Heat
    Refrigerator
    Microwave
    Family room wall sockets

    What else would you need?
  11. mbwayne

    mbwayne New Member

    Messages:
    3
    Location:
    Pennsylvania
    I think the materials would be about $500 ($350 for 10-switch panel; $90 for 40' 10/4 cable; $50 inlet box), so I agree that $1100-1350 for labor seems a little high, but that was the range from 3 electricians in my area (maybe post-hurricane price jump?). As for number of circuits, the price difference from 6 to 10 circuits isn't that great, and I'm sure I'd appreciate a few more circuits when needed (although not at the same time).

    In any event, sounds like some heavy gauge extension cords will be the way to go until I can do the transfer switch. A bit tricky in the dark with kids and dogs, but should only be in rare emergency situations.

    Thanks again for the input.
  12. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,570
    Location:
    North Carolina
    You came here asking two questions which you got a good safe and code compliant answer to.
    Not only that but you also got the installation instructions for a transfer switch should you decide to use one as outlined by UL
    ENGINE GENERATORS FOR PORTABLE
    USE (FTCN)
    GENERAL
    This category covers internal-combustion-engine-driven generators rated 15 kW or less, 250 V or less, which are provided only with receptacle outlets for the ac output circuits. The generators may incorporate alternating or direct-current generator sections for supplying energy to battery charging circuits.
    When a portable generator is used to supply a building or structure wiring system:
    1. The generator is considered a separately derived system in accordance with ANSI/NFPA 70, ‘‘National Electrical Code’’ (NEC).
    2. The generator is intended to be connected through permanently installed Listed transfer equipment that switches all conductors other than the equipment grounding conductor.
    3. The frame of a Listed generator is connected to the equipment grounding conductor and the grounded (neutral) conductor of the generator. When properly connected to a premises or structure wiring system, the portable generator will be connected to the premises or structure grounding electrode for its ground reference.
    4. Portable generators used other than to power building or structure wiring systems

    Then you post the post above.
    Let me say that I know you are going to do what you are going to do but once again before you go and spend all that money think about the safety of your family first above watching TV
    Also don’t be too disappointed if you have to keep going outside to restart that generator or if you lose a lot of electrical equipment
  13. Gary in NJ

    Gary in NJ New Member

    Messages:
    90
    Location:
    NJ
    It would appear that you came here to get support for your decision, clearly you don't want advice. Just so incorrect information isn't left in this thread, I will correct your material costs noted above:

    1 ea. Square D 8 Circuit/Space Transfer box is $99 at Lowes
    http://www.lowes.com/pd_28277-296-QO48M60DSGP_4294821907_4294937087_?productId=3128391&Ns=p_product_prd_lis_ord_nbr|0||p_product_qty_sales_dollar|1&pl=1&currentURL=%2Fpl_Load%2BCenters_4294821907_4294937087_%3FNs%3Dp_product_prd_lis_ord_nbr%7C0%7C%7Cp_product_qty_sales_dollar%7C1&facetInfo=

    4 ea Square D Tandem Homeline Circuit Breakers are $44 at Lowes ($11 ea)
    http://www.lowes.com/pd_4372-296-HO...7087_?Ns=p_product_price|0&facetInfo=Square D

    1 ea Load Center Outdoor Connection is $28 at Lowes
    http://www.lowes.com/pd_242306-8236...8_4294937087_?Ns=p_product_price|0&facetInfo=

    2 each 250V/30A - 3 wire plug at Lowes $38 ($19 each)
    http://www.lowes.com/pd_197490-334-...br|0||p_product_qty_sales_dollar|1&facetInfo=

    Wire ~ $50

    Total cost of materials about $260.

    I see that you've shown 40' of 10/4 cable. You should consider putting your outside hook-up on the same wall as the main & subpanel box (just opposite of them actually) which is where you will also find your outside meter. Place the generator within 6' of the outside hook-up. This will reduce the cable length from 40' to 10'.

    Sometimes you have to install things correctly versus how you want them.


    Edited to add

    I am editing this post to add one more link to the UL white book

    http://www.ul.com/global/eng/pages/offerings/perspectives/regulator/electrical/newsletters/

    once open search for FTCN and see how things have changed in the past three years concerning these small generators.
    Last edited by a moderator: Oct 21, 2011
  14. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,570
    Location:
    North Carolina
    Gary please forgive me for editing your post but I see the need to push hard to stop these small generators from being connected to house panels. I don’t have the numbers in front of me at the moment but many have been hurt by these small gen sets and the home owner trying to use them improperly. There is a big push in the electrical trade by many to enlighten people of the dangers involved.
    From being shocked by floating neutrals to parallel equipment grounding when refueling to even fires.
    The floating neutral can leave a home with a series 240 volt system instead of the 120 volt parallel that we all know and use.

    My strong advice is to use the proper cord from the generator to the appliance severed
  15. Gary in NJ

    Gary in NJ New Member

    Messages:
    90
    Location:
    NJ
    OK, now I have a question...

    I'm using L1430C connectors on my cable between the generator and outdoor box. I'm using six feet of 10/4 90C water resistant cable from the generator to the outside hook-up and then an additional 4 feet of the same cable between the outside hook-up and my transfer switch (the very same Square D I referenced above).

    Does this not meet paragraph 2 noted above: "The generator is intended to be connected through permanently installed Listed transfer equipment that switches all conductors other than the equipment grounding conductor."

    My well pump (240V) and other circuits (120V) all work fine with this configuration.
  16. ActionDave

    ActionDave Electrician

    Messages:
    368
    Location:
    Colorado
  17. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,570
    Location:
    North Carolina
    It could have been compliant when installed but it is no longer compliant to install one today.
    There have been major issues with this type of installation paralleling the neutral and equipment grounding conductor between the transfer and the generator itself. This leaves the frame of the generator at the same level as the circuit being supplied.

    If the neutral was lifted from the frame of the generator and one leg of the 240 volts then shorts to the frame of the generator there is no fault current path to open that leg and then the equipment grounding conductor of the generator is raised to the same level as the shorted leg.
  18. Gary in NJ

    Gary in NJ New Member

    Messages:
    90
    Location:
    NJ
    So should I ground the frame of the generator to the ground cable at the breaker panel?
  19. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,570
    Location:
    North Carolina
    If your generator has the receptacles mounted on the frame of the generator then the neutral point of that generator winding should be bonded to the frame.
    The grounding terminal of the receptacles mounted on the generator is also bonded to the frame.
    In the event of a ground fault the faulted current travels back to the frame on the equipment grounding conductor and from the frame to the neutral point of the generator winding causing a high current draw which opens the overcurrent device which on most generators is a reset button.

    To connect this generator to the wiring system of our business and homes causes a parallel path between the equipment grounding conductor and the neutral as the service disconnect will have this same bonding as is found on the generator. When the equipment grounding and neutral become tied together at the service it makes the equipment grounding conductor in the cord connecting the generator to the building carry part of the current that is carried on the neutral and this makes the frame of the generator at the same potential as the circuit or 120 volts.

    To relieve this parallel path some will lift the neutral from the frame of the generator and let it float so to speak. When this is done and one winding of the generator short to the frame there is nothing to shut down the overcurrent device or the generator and the equipment grounding of the generator is energized to 120 volts. Now we have 120 volts supplying the 120 volt receptacles and the other 120 volts supplying the equipment grounding conductor or we have 240 volts at the 120 volt receptacles.

    This is why that UL has made the changes to their listing of how to install one of the self-contained generators where we can no longer use these type of installations and the generator MUST be installed as a Separately Derived System or the use of cords for each appliance must be used.
  20. Gary in NJ

    Gary in NJ New Member

    Messages:
    90
    Location:
    NJ
    Got ya. Thanks for the detailed description.
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