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Pluggng a generator into the NIMA 14-50 outlet

Discussion in 'Model S: Battery & Charging' started by mrjedistud, Mar 1, 2016.

  1. mrjedistud

    mrjedistud Member

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    When I had the NIMA 14-50 installed in/outside of my garage, the electrician told me that if I need to, I can plug a generator into the outlet and backflow power into my house.
    I would have to shut off any nonessential switches in the main power box, but the back flow would be fine for lights, heating system, etc.
    It actually sounds logical and convenient since now I don't have to rewire the box to handle the generator.

    Has anyone had experience with this? Is it really that straight forward?
     
  2. MP3Mike

    MP3Mike Active Member

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    You can do it, but it isn't necessarily a good idea. And if you do make sure you turn the main breaker off so you don't feed power to the utility line. (Which could cause a line man to get electrocuted trying to get you hooked back up. Or for that matter anyone else that comes in contact with a downed line.)
     
  3. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    #3 FlasherZ, Mar 1, 2016
    Last edited: Mar 1, 2016
    That is a very bad idea because to do it you have to create what they call a "suicide cord" with plugs on two ends. It also has massive safety problems. They call them "suicide cords" for a reason.

    I regularly read stories about power companies experiencing these. The good news is that operational practice with power companies has improved -- linemen deaths are becoming rarer because the power companies are taking more care. For example, they disconnect and ground downstream conductors while working on a problem. You don't want to be responsible for someone's death, so do it the right way...

    You want to install a generator inlet with proper manual (or automatic) transfer switch.

    And no matter how much you swear that *you* will remember to follow all the steps correctly, other people might try the same. Just a bad idea.

    Beware of Backfeeding - How NOT to Connect a Portable Generator
     
  4. msnow

    msnow Active Member

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    One of the crazier posts I've seen in a while.
     
  5. SabrToothSqrl

    SabrToothSqrl Active Member

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    Physically possible? yes. it is.

    Safe: it is not.
     
  6. DCGOO

    DCGOO Member

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    Widow maker also comes to mind. Bad idea. Don't go there.
     
  7. Rocky_H

    Rocky_H Member

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    Other people seem to be not mentioning the elephant in the room, but an ELECTRICIAN told you this?!?!
     
  8. mrjedistud

    mrjedistud Member

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    Thanks for the feedback. I'll stay away from that set up.
    In Fairness, the electrician may have given me a bunch of other cautions or precautions, but I may not be remembering it all.
     
  9. patrick40363

    patrick40363 Member

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    You need a transfer switch.
     
  10. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    Good idea. :)
     
  11. Patrick W

    Patrick W Member

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    I was told by my electrician that even turning off the main breakers will not keep power from the generator from getting out to where it could hurt power company workers. He said a transfer switch is needed.

    That was pricey so I ended up just having him fix the furnace so I could unplug it from house power and run it from the generator. That means only the furnace will work if power goes out but that's all I really need.
     
  12. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    Your electrician told you a lie, but that's ok because it was probably designed to dissuade you from doing something stupid. :)

    A transfer switch is needed so that there is no possibility of forgetting to turn off the main, or switching them in the wrong order and sending boatloads of current through the windings on your generator, burning it up and causing a fire.
     
  13. wk057

    wk057 Senior Tinkerer

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    When I was like 10 years old my father and I had made a mini 12V off-grid solar system with like a single 40W panel, a bunch of old car batteries, and a 200W square wave inverter. Fun times. We used it to run a small TV, a light or two, and sometimes my old computer.

    I got the bright idea that I could run the light in my bedroom by making a male to male 120V cord and using one of those screw in 120V sockets that sit between the light fixture and the light bulb, then feed it from the inverter. It worked great until someone came in and tried to turn on my light and blew up my inverter. :(

    Thinking on a larger scale with a generator, seems pretty crazy to attempt it. Admittedly, I've done it in a pinch, but I red taped the main breaker, not that I think anyone would get any ideas. Was during a multi-day outage in NJ a while back.

    Transfer switches are pretty cheap. Just get one, and a sub panel, and just put your mandatory loads on the sub panel. Can probably do the whole job for $500 or less if you know what you're doing. Well worth the effort.

    My solar setup actually has three different transfer switches. A manual one to flip me between inverter and grid power, one in the inverters that can flip between inverter and grid power, and another in the inverter that can flip to a generator (nothing connected here with my system currently). So, I'm pretty well covered.

    Long story short, pays to just do it right.
     
  14. brantse

    brantse Member

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    I'm sure I'll be lambasted for saying it, but this is exactly what I plan to do. I already have the male 14-50->male L14-30 "suicide cord" made up. In the past I either used a similar cord and backfed through my dryer outlet, or had a cord made up with a 50 amp breaker on it that I would swap in at my hot tub's GFCI panel.

    Yes, I do understand that this is 1) illegal, 2) dangerous (if done incorrectly), but I have decided that for the few times I may need to do it, installing a transfer switch is just outside of the realm of reasonable. Especially considering that I have a well pump, heat pump that I believe requires 8 breaker slots, multiple refrigerators/freezers, etc. that would all need to be powered.
     
  15. sandpiper

    sandpiper Active Member

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    I did this once years ago as a desperation measure. We had a multi-day power outage and I was concerned about pipes freezing. I wasn't worried about the suicide cord but I was absolutely paranoid that I would forget to shut off the main breaker, potentially resulting in a kaboom or a fire when the line power came back on. And that would be a really easy thing to do, as the lights are out and you're fishing around in the dark, plugging things in and firing up a generator.

    I would certainly not intentionally install such a setup, planning to use in in power outages. Get a transfer switch.
     
  16. RDoc

    RDoc S85D

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    For anyone considering this, think about how you'll feel if you wind up electrocuting a power worker or someone else who thinks that the external line is de-energized. Transfer switches are cheap, you can get them on Amazon.
     
  17. AMPUP

    AMPUP Member

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    I have a setup like this specifically for a generator, it had a lock in the panel that only allows you to feed the panel from the generator if the main breaker is off. I believe it's called a generator interlock kit.
     
  18. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    It takes just one forgotten step before you go to prison for killing a lineman.

    - - - Updated - - -

    Correct... it ensures that the generator breaker can't be turned on unless the main is off. Nearly every panel has an option.
     
  19. tga

    tga Active Member

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    When I was a kid, I built electromagnets, transformers, etc. I spent hours "mining" for iron filings at my grandparent's beach house with a homemade electromagnet powered by a big No 6 dry cell (2.5" dia x 7" length).

    One day, in my bedroom, I decided that if 1.5V was good, 120V would be better (hey, I was 7 or 8 at the time...). I stuck the wires from the electromagnet into the outlet on an extension cord, and *bam!* Needless to say, i discovered quickly that wasn't a good idea. My parents still have the cord with the charred hole in the outlet.

    That may be too much to power through a 14-50, anyway...

    I have one of these installed in my main panel: GE PowerMark Gold Load Center/Generator Interlock Kit-THQLLX1 - The Home Depot

    I can post a picture later. You shut off the main, slide the interlock, and turn on the backfeed breaker. To switch back, backfeed off, slide interlock, turn main on. It enforces the necessary "break-before-make." I can't use a standard Reliance/Generac transfer panel, as I have critical loads in the main panel (furnace) and a remote sub panel (air handler in attic).
     
  20. brantse

    brantse Member

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    That's for a single 120V circuit. In order to provide power to all of my "necessities", I would need close to a dozen circuits, many of which are 240V. And don't forget about how difficult it is to install/wire these, especially in a flush mount panel.

    - - - Updated - - -

    Understood. There are many situations in which we are one step away from disaster. I have enough faith in myself that I won't make that mistake. The amount of effort required to haul my generator out and prepare it to connect, is enough that nobody but myself is ever going to do it.
     

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