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View Diary: Generators and Big Storms (65 comments)

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  •  The simple way (2+ / 0-)
    Recommended by:
    sceptical observer, NYFM

    is to turn the main breaker off and plug the generator in to the big dryer outlet.

    •  One way or the other. (6+ / 0-)
      So here is my question:  

      The electrician told me that although it is not approved by the electrical company I should leave a main panel breaker switch on, and one circuit breaker for a hall light on, so that I could tell that the utility power had returned when the hall light came on.

      I think that's insane, and have decided not to follow that advice.  I don't like  the thought of utility power and generator power charging into my panels at the same time.

      concur. If the main breaker is on you are powering your neighbors and probably overloading your generator. When the electricity comes back on it is likely to be out of phase with your generator. You need a better electrician.
    •  ? That's a good way to burn down a house, (0+ / 0-)

      so you must be joking.

      •  The dryer outlet is the biggest (0+ / 0-)

        circuit breaker and lives on both sides of the 220 panel.

        •  The problem with this (2+ / 0-)
          Recommended by:
          SquirmyRooter, Timaeus

          is that the dryer outlet is usually in the house or in the back of the garage. This requires a very long, high current cord to get the generator outside the house. There is always the danger of carbon monoxide if it is not far enough away. It is better to install another high current outlet on the outside of the house with its own breaker. Most local power companies frown on this because the feed lines can be energized by the generator if you forget to open the main breaker.

          When the F**K are we going to wake up and do something about this mess?

          by keyscritter on Thu Jun 13, 2013 at 08:01:05 PM PDT

          [ Parent ]

        •  Sorry - but not a good plan (7+ / 0-)

          First, the dryer outlet is 240v, and a lot of people only have 120v generators.

          Second, a dryer outlet is probably a 30 amp circuit (dryers are usually around 5kW) - 30 amps is not a lot for people used to 200A or 400A service.

          Third, 30A at 240V is 7200W, but most of a typical residence is 120V. This is almost universally done in a bi-phase system where the phases are 180 degrees out-of-phase and each phase drives on column in the breaker box. Loading is rarely balanced - typically all the 240V stuff goes down part of one column and the rest of the column and the other one are 120V. If one column draws 40A and the other 20A, both at 120V, that's still 7200W, but the 30A dryer circuit will trip.

          The range breaker is usually 60A, but you have to pull the range out to get at the outlet.

          Lastly, any solution that connects to building wiring without a transfer switch is dangerous, both for utility workers and homeowners. In the middle of a severe storm a lot of people aren't going to remember to flip the main breaker off (a lot of them don't even know what it is or where). It's just like people who think their Weber grill would be great for heat and cooking in the living room and die of carbon monoxide poisoning. More than one person does that in most power outages - it only takes one to kill a utility worker.

          No matter how cynical you become, it's never enough to keep up - Lily Tomlin

          by badger on Thu Jun 13, 2013 at 08:59:31 PM PDT

          [ Parent ]

          •  Folks that have 110V only generators should (4+ / 0-)
            Recommended by:
            Lujane, SquirmyRooter, Timaeus, BachFan

            stick to extension cords. These can not be safely connected to house wiring.

            Most residential feeds in the US are 240V, two wire, balanced to the neutral, either side gives 120v to the neutral.

            The safest way to connect a generator is via a transfer switch installed by an electrician. I believe that this is the only method supported by the electrical code. There are other methods that will work in an emergency but they require knowledge of how these systems work. They have inherent risks that the transfer switch is designed to reduce or eliminate. If folks do not have that knowledge then they should not attempt to try those methods. The first rule is that the service mains and the generator should never drive the breaker panel at the same time. Most "home" generators are not designed to sync to another power feed. If both feeds are hot the generator will lose a producing a dangerous result. Both solar and wind systems produce AC power through invertors which are designed to sync with local power.

            When the F**K are we going to wake up and do something about this mess?

            by keyscritter on Thu Jun 13, 2013 at 10:00:42 PM PDT

            [ Parent ]

            •  Aye. Nothing wrong with extension cords. (1+ / 0-)
              Recommended by:
              Timaeus

              A 12-Guage extension cord will support 16 amps for 50 feet.  This doesn't apply to the diarist, but for anyone looking for a more economical way to feel secure about their refrigerated medication or other necessities, there is nothing wrong with running a good quality extension cord directly from your generator to your refrigerator.  You don't need an electrician for this.  I've run such extension cords through my kitchen window to a generator positioned away from the house.

              For anything else, either know what you are doing (I mean really know what you are doing) or hire an electrician.

              Rooting for Democrats!!!

              by SquirmyRooter on Thu Jun 13, 2013 at 11:04:24 PM PDT

              [ Parent ]

              •  Yep, our generator came with four very heavy (1+ / 0-)
                Recommended by:
                SquirmyRooter

                extension cords tied together with a length of about 10 feet (to which one could attach longer, heavy cords).  But I decided a transfer switch was safer.

                For one thing, if you used extension cords, you'd have to make a port through a wall, or keep a window or door open, not a good idea in a big storm.

            •  Voltage is balanced in a bi-phase system (1+ / 0-)
              Recommended by:
              Timaeus

              Load isn't.  The current return of a single 120V phase is to ground/neutral, not to the other phase - the current per phase is only guaranteed equal for 240V loads.

              Transfer switches like this are designed for 120V only operation and transfer on a circuit-by-circuit basis, rather than transferring the mains. Perfectly safe for connecting a 120V generator to house wiring.

              It's basically a panel of single-pole/double-throw switches. The common is the circuit to be energized, one throw comes from the breaker in the service panel, the other throw from the generator.

              No matter how cynical you become, it's never enough to keep up - Lily Tomlin

              by badger on Thu Jun 13, 2013 at 11:11:30 PM PDT

              [ Parent ]

    •  Very Dangerous (7+ / 0-)

      The problem with this assuming you keep the generator far enough from the house, is that if you forget to turn off your main, you are energizing the lines that go to your house. If someone working on those lines doesn't take the proper precautions, they can get electrocuted and sue your pants off. The second problem is (maybe an electrician can explain why) is that when a generator is attached to your home power lines it needs to have its own ground. That means driving a stake 6 feet into the ground, which isn't easy to do. If you don't do this you run the risk of electrocuting you or anyone else in the household. I'm not sure why you don't need to ground a generator that just uses extension cords, but you don't. The minute you attach a generator to a home power system, you need to have a transfer switch.

      •  Hmm. We were told that with our gas (0+ / 0-)

        generator connected by a heavy cable to the transfer switch, no separate ground was necessary for the generator.

        We got a Briggs & Stratton StormResponder with 5500 Watts (8250 Watts peak).  The owner's manual says:  "System Ground.  The generator has a system ground that connects the generator frame components to the ground terminals on the AC output receptacles.  The system ground is connected to the AC neutral wire (the neutral is bonded to the generator frame)."

        Alas, I have no idea what that means.  I think I'll call the electrician.

        •  Neutral isn't always neutral. (1+ / 0-)
          Recommended by:
          Timaeus

          Most houses have a ground rod somewhere that works. I have several weeks of Army generator training.

          The key appliance at Chez aoeu is the furnace and it does not have a cord.

          I have battery powered CO2 alarms.

          This has been an interesting and useful diary.

        •  The electrician called right back! (0+ / 0-)

          They put a ground wire into the very heavy 20 foot cable from the generator to the transfer switch in the house, so the generator is grounded by the house's grounding system.

        •  Hmm. We were told that with our gas (0+ / 0-)

          This just means the generator uses the building ground connection (usually at the service entrance). So yes, the generator does not need it's own ground.

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