question on home generator/electrical

Discussion in 'Technical Corner' started by alanbreck, Apr 16, 2020.

  1. Ghery

    Ghery Touchdown! Greaser!

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    Absolutely they should check, but mistakes happen.

    I remember in my first job out of college the process at the shipyard to work on an electrical device required that our group (tech code) had to issue a breaker line up that listed all the breakers that had to be opened and fuses that had to be pulled to kill all power in the cabinet to be worked on. The list then went to the test code who might have some test running that required deleting a breaker or fuse from our list. It had to go back to us before being approved because we might have some overriding safety reason why it had to be included. It then went to ship's force for their review. Same drill, if they deleted something it had to go back to us. Once all three groups were happy then the mechanic could go down to the boat and do his thing. We had an incident where someone deleted a breaker or fuse from the list without checking with us and when the mechanic went down to the boat he got bit by 440 VAC. Fortunately he wasn't killed. Big issue over that. We (tech code) weren't at fault, but NRRO (Naval Nuclear Reactors Office - Rickover's Gestapo) decreed that the fix was for us (the innocent party) had to get our manager's signature on a breaker lineup before releasing it. We created theses lineups before the boat even arrived at the shipyard! Oh well, it gave me great satisfaction one Saturday night (late, probably early in the morning) to call my boss at home, wake him up from a sound sleep, and get his telephone concurrence to a lineup. All because someone in another group and failed to follow the established process. Oh well...
     
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  2. -KLB-

    -KLB- Pre-takeoff checklist

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    Stolen from the inter webs, and I haven’t validated, these look like possibly some of the best documented evidence that backfeeding can kill:

    a couple of OSHA documented deaths....

    90-05 Lineman electrocuted while attaching a 2400V powerline to a pole-mounted insulator. Victimassured by supervisor that line was deenergized, but it was in fact energized by portablegenerator.

    90-02 Leader of tree-trimming crew electrocuted during hurricane cleanup when he contacted adowned powerline he believed to be deenergized. Electric current from portable generatoroperating at gas station nearby reenergized powerline.

    http://www.cdc.gov/niosh/pdfs/98-131.pdf
     
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  3. flyingron

    flyingron Touchdown! Greaser! PoA Supporter

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    Again, it should be sufficient that it is illegal and unsafe. A simple mechanical transfer will suffice and costs less than $200.
     
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  4. Jim Rosenow

    Jim Rosenow Line Up and Wait PoA Supporter

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    A physical lock-out between the main breaker and generator circuit was like $40. I can start my gennie from the breaker box, so manual is good for us... ACD864EA-2137-4DD2-BABE-220BC7811A7A.jpeg 4FA59837-7516-47F9-AECD-D68616F814BD.jpeg

    Jim
     
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  5. -KLB-

    -KLB- Pre-takeoff checklist

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    The really funny observation is that we are in a forum where we should understand that fatalities are often the result of a series of low odds, preventable errors or omissions, and the need for a legally required interlock is being questioned.
     
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  6. flyingron

    flyingron Touchdown! Greaser! PoA Supporter

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    In fact, if you don't have a generator that's big enough to run the entire expected load that is connected to it, you can't use an automatic transfer anyhow. With a manual transfer/interlock, they assume you'll be smart enough to shed unnecessary loads prior to transferring to the generator.

    My story is sort of bizarre. What I had spec'd to the architect was that we were supposed to have two panels: one with the essential loads on it: well pump, fridge/freezer, and a few other important loads. We could then put the essential panel on the ATS to the generator and I could get away with smaller everything.

    Well, I'm an electrical engineer, and the architect is not, so he hires this other EE firm. I was livid at the response. First off, I was able to specifically detail nearly two pages of things that were just outright against the code, let alone things that in my opinion were bad ideas. Fortunately, my electrician said he'd have not built it as drawn anyhow. HIs license is the one that would have been on the line. Anyhow, by the time I went back and forth dealing with that, I got down to the fact that rather than doing the essential/non-essential determinations I asked for, they just spec'd a generator that could run the entire 400A service going into the house. I said, WTF, put it in that way. I was tired of arguing.

    After the first phase of the house was done and the generator was installed and the utility connected, the electrician and I were standing there looking at the main utility disconnect. He smiled at me and said "Aren't you going to test it?"

    [​IMG]

    The above picture shows the meter base, the main disconnect, and the transfer switch. I reached up and pulled that big honking switch down to sever me from the utility. The generator cranks up and the ATS goes THUNK.

    I misspoke above by the way. I was reading through the HTS docs and it also controls the generator cool down after the power is restored.
     
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  7. PaulS

    PaulS Touchdown! Greaser!

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    Who is questioning the need for an interlock? I missed it.
     
  8. Jim Rosenow

    Jim Rosenow Line Up and Wait PoA Supporter

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    What's your fuel source, flyingron? That's gotta drink some!

    Jim
     
  9. redtail

    redtail En-Route

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    Poor fella. I hate to hear that kind of ****! I'm glad we never relied solely on a supervisor's "assurance". :rolleyes:

    I'm not sure why he didn't hotstick the line before working on it or if he had proper PPE.

    At the very least....

    I realize that's not practical in a situation like this, but still...

    Aren't linemen trained to assume someone could possibly be backfeeding a transformer with a portable generator, turning it into a step-up transformer???

    On second thought, I shouldn't question what training he may have had, because I've seen guys take all kinds of shortcuts on my job over the years! Not linemen, but we're on the other side of the grid (customer).

    They were properly trained, but some got lazy. One guy never donned PPE and we work with everything up to 13KV.
     
    Last edited: Apr 23, 2020
  10. flyingron

    flyingron Touchdown! Greaser! PoA Supporter

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    There's a 1000 gallon propane tank just beyond it. It actually doesn't burn that much. It's run for days without making much of a dent in the tank.
     
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  11. flyingron

    flyingron Touchdown! Greaser! PoA Supporter

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    Sure, but that doesn't mean it's safe for them. Do you find what breaker protects a given circuit by jamming a screwdriver in the outlet?
     
  12. Greg Bockelman

    Greg Bockelman Touchdown! Greaser!

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    That reply doesn’t make much sense, much lest common sense.
     
  13. -KLB-

    -KLB- Pre-takeoff checklist

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    Yes, but what if between the point he tests, and the point he finishes work, somebody fires up that generator, trying to figure out why it only runs 3 seconds before kicking out? Or fires it up to run the refrigerator for an hour before shutting it down? What if there is switchgear between the subscriber and the tech that was open when he started, but another worker went ahead and closed it in preparation?
     
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  14. flyingron

    flyingron Touchdown! Greaser! PoA Supporter

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    It makes perfect sense. The only way to make sure the line they were working on is dead is to make sure they bond it to ground.
     
  15. -KLB-

    -KLB- Pre-takeoff checklist

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    I may be reading too much into someone asking if the generators breaker would kick out if it back fed the grid. In other forums, questions like that are often precursors to people planning to do stupid things. And while the general case would be for the breaker to kick out, the two OSHA cases illustrate that it doesn’t always work that way.
     
  16. Greg Bockelman

    Greg Bockelman Touchdown! Greaser!

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    Well yeah, but the jamming a screwdriver in the socket analogy is what doesn’t make sense.
     
  17. RyanB

    RyanB Administrator Management Council Member PoA Supporter

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    Absolutely. You can bet your britches they don’t work on hot wires.
     
  18. PaulS

    PaulS Touchdown! Greaser!

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    Yeah, you're reading too much into it, especially since I said that I wouldn't do it and it shouldn't be done before I asked the question, then repeated it in subsequent posts.
     
  19. flyingron

    flyingron Touchdown! Greaser! PoA Supporter

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    Except for this guy...

    There's only three things I've ever been afraid of... electricity, heights, and women.
     
  20. weilke

    weilke Touchdown! Greaser!

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    Local county dispatch center did the same test after some reliability upgrades to the power failover system. Head of facilities pulls the mains switch, something went THUNK and the entire facility was in the dark until a rack of melted equipment could be bypassed.
     
    Last edited: Apr 23, 2020
  21. PaulS

    PaulS Touchdown! Greaser!

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    Actually.... They do work on hot wires in certain circumstances. Our local municipal electric company begs people not to fasten yard sale signs to utility poles because it can inadvertently put pinholes in their gloves and get them electrocuted, although I'm not sure if they actually work on live lines.

    We used to do work for a company that needed to switch loads remotely on very high voltage lines remotely as part of a system to reduce induction losses on the lines. They used fiber optic cable to send a signal the a contactor that would switch their system into and out of the lines as needed. The fiber cable was not conductive and perfect for the job, the contactors were powered by the lines. They would go up and work on the systems occasionally while the lines were hot. They would connect to the lines some how and be able to safely work up there. The engineer came to us with a story one time, they had rented a boom truck that was supposed to be safe for this type of work. The operator got to the line, and connected to it, when he did this there was a big flash and the truck tires exploded. A previous renter had run some type of communication cable through the boom and didn't remove it, no one caught it. The operator didn't get hurt other than probably soiling his pants.

    https://en.wikipedia.org/wiki/Live-line_working
     
  22. forsonsinc

    forsonsinc Pre-takeoff checklist

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    While we are nit picking thats lest than perfect spelling. I did understand what he was attempting to say though.

    And no I didn't read anyone question interlocking devices either.
     
  23. forsonsinc

    forsonsinc Pre-takeoff checklist

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    Electricity is no joke, in the 80's (No not me)operating a crane near power lines got to close and the guy running the tag line died ..it wasn't close in the eyes of the locals..even heard one of the men say yes done the same thing many times. Leads me to believe it's quite unpredictable.
     
  24. Ghery

    Ghery Touchdown! Greaser!

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    500 kV off the intake deck of the hydroelectric dam I worked on as a co-op in college would ruin your day in a very short period of time. Heck, the 13.2 kV off the generators on the primary of the step-up transformers would have done the job, too. That was an interesting summer. I haven't worked heavy construction since the following spring when I worked for the contractor again before graduating with a BSEE, but I certainly learned some very useful stuff while there.
     
  25. flyingron

    flyingron Touchdown! Greaser! PoA Supporter

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    480V was enough for me. Years ago I was working at the US Army. Our computer room had this power distribution unit (essentially a computer monitored 480-208 step down transformer and distribution panels). One evening I'm running a new stretch of liquid-tight conduit under the floor. Unbeknownst to me, it is riding up on top of the other conduit coming from the PDU, and is now headed inside the unit where it contacted with the primary terminals of the transformer.

    It got quiet in their real fast as I tripped the main 400A breaker on the thing. After I realized what happened I noted that the EMERGENCY STOP buttons were not lit up. The control logic for this was on a separate circuit than that main breaker. Of course, my coworkers who were up using the computers in their offices came down to see what had happened. I told them I was fine but someone needed to run over to the other building and get the master key from the guard because we needed to go down and reset the breaker on the substation.

    When I pulled the conduit back out, I found that the nut on the end was welded in place. The next day, a new sign appeared on the door of the computer room:

    Ron's Welding Service -- Arc welding a specialty.
     
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  26. Kenny Phillips

    Kenny Phillips En-Route

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    What? You don't backfeed through an outlet in the house? I've seen it done; not recommended.
     
  27. RyanB

    RyanB Administrator Management Council Member PoA Supporter

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    I’m not sure where you got that from. I said nothing like that. Generator power is controlled externally via our main breaker box. The main 200amp is shut off, and the 30amp powered by the generator is flipped on and we can pick and choose what to run from the breaker panel in the house.
     
  28. flyingron

    flyingron Touchdown! Greaser! PoA Supporter

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    Suicide cord?
     
  29. Greg Bockelman

    Greg Bockelman Touchdown! Greaser!

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    Only if you don’t respect it. LOL
     
  30. PaulS

    PaulS Touchdown! Greaser!

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    Geez, I haven't seen anyone say not to back feed the grid, come on guys! :rolleyes:
     
  31. RyanB

    RyanB Administrator Management Council Member PoA Supporter

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    Everyone loves to jump to conclusions and create words that haven’t been said. It just shows a lack of understanding as far as I’m concerned.
     
  32. PaulS

    PaulS Touchdown! Greaser!

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    I feel your pain Ryan.
     
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  33. MauleSkinner

    MauleSkinner Final Approach

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    When I was a teenager, my grandpa and I were doing some electrical work in a shed. Rather than send me up the hill to trip the breaker that fed into the box in the shed, he just took a screwdriver (probably about 3/8” diameter shaft), stuck the end of it into the corner of the box, and then contacted the middle to the hot lead coming into the box.

    Once the sparks settled down, he looked at the screwdriver shaft where it was melted almost all the way through, looked at me, and said, “I guess that’s why we should do it the right way.” A good lesson, anyway. ;)
     
  34. jsstevens

    jsstevens Final Approach PoA Supporter

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    Back in the dark ages (well, shortly after because we DID have electricity) my dad (a licensed electrician) had a short cord with a switch to short the hot & neutral. He’d use it to find breakers by shorting the circuit and then see which breaker kicked. He told me it worked on everything except Federal Pacific. I’ve shorted two hot wires (240V) to find a breaker. Used a 2x4 to push them together. Had to do it 3 times before it finally kicked. I don’t trust FP and finally UL figured it out. They have to be replaced before you can sell your house.
     
  35. RJM62

    RJM62 Touchdown! Greaser!

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    That doesn't protect him again idiots hooking up a backfeed through their dryer outlets while he's working. Interlocks are legal in most jurisdictions, cheap, and easy to install.

    This is my DIY generator installation. Legal, up to code, and won't get anyone killed. Took about half a day, start to finish.

    Rich
     
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  36. denverpilot

    denverpilot Tied Down PoA Supporter

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    Also for those pondering the need for disconnects — other types of “outages” happen. Continuous brown-outs, or single phase losses with others still hot...

    Been there done those.

    Always disconnect completely from upstream when operating on the genny. Completely. Safety AND because the real world gets weirder than you think it will. :)

    If you really want to start a fight, ask the elec-chicken if the safety frame ground of a genny should be bonded to the safety ground of the building.

    And then go see how many genny manufacturers screw up that particular little detail in their “ground lug”... and whether or not it’s connected to neutral inside the genny...

    Get. An. Electrician. To. Install. The. Cutoff. And. Have. The. Generator. Sitting. There. That. You. Will. Use. :)

    :) :) :)
     
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  37. jsstevens

    jsstevens Final Approach PoA Supporter

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    I'd double like that one if I could! Here in Florida, where we have nearly daily thunderstorms in the summer (which is roughly 42 months long) there are all kinds of bad power. Surge suppressors and smart UPS coupled with generator to back up the UPS is how we stay sane.
     
  38. flyingron

    flyingron Touchdown! Greaser! PoA Supporter

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    We only have single-phase power here so I'm not concerned about single phase dropouts separate from complete power failure.
    We see very few "brown outs" here. We were on the generator for about 45 minutes this morning.

    The real ****er is that the stupid phone company doesn't have backup power here. I lose my landline phone and the internet when the power is out on the next street over.
     
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  39. weirdjim

    weirdjim Ejection Handle Pulled

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    Assuredly, run your generator dry after the season is over and use fresh gas for the next season. Two comments to that:
    1. In California for the last few years, the rainy season lasts until the summer fire season, lasts into the next rainy season... there IS no "next" season.
    2. If you use 100LL for your gas generator you can screw up a few times and that 5 year guaranteed not to gum up for avgas will save your hiney.

    Jim
     
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  40. RJM62

    RJM62 Touchdown! Greaser!

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    One ounce of the Marine flavor of STA-BIL for each five gallons of corn-free mogas will last for at least two years (although I typically rotate after one).

    Rich