final questions on manual transfer switch

Discussion in 'Electrical Forum discussion & Blog' started by zunden, Jan 28, 2011.

  1. zunden

    zunden New Member

    Messages:
    11
    Location:
    DC, USA
    I have incorporated the advice in my previous thread on installing a manual transfer switch(Gen-Tran 60 amp utility feed/30 amp generator supply) into a detailed description of work, and have four remaining questions:

    When I remove a circuit's NM-B from the left service panel(because the feeder breaker is installed in the right panel) and splice it in a junction box, should I run the new NM-B directly to the transfer switch?

    When I splice grounding wires from the right service panel to the ground bar in the transfer switch, should I use bare or insulated wires?

    When I splice load conductors from the right service panel, is it better to set aside the blue THHN provided by Gen-Tran and use colors which match the existing conductors?

    How should I distribute my three 1-pole breakers between the A and B sides of my transfer switch panelboard to balance the generator load? (My only 240V circuit is the well pump which pulls 8 amps. I can conveniently disable the furnace with the thermostat when water is needed.)

    20 amp furnace breaker: furnace pulls 19 amps when the burner is running.
    20 amp small appliance breaker: refrigerator pulls 7.2 amps; usual kitchen appliances.
    15 amp bathroom lighting/ventilation breaker: a fan and a couple of lights would pull 1 amp.

    (I apologize to Rick for proposing 10-UP in 3/4†RNC after he advised 4 - #10 THHNs.)

    Thanks as always for your help.
  2. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,534
    Location:
    North Carolina
    Yes along with any other circuit that you are wanting to have on the back-up generator

    this would be up to you.

    The only conductors that color would matter on would be the white neutral and green grounding conductors. All the rest can be any color your heart desires.

    Try to keep it balanced or as many on one side as on the other.
  3. Northerner

    Northerner New Member

    Messages:
    6
    Location:
    Vermont
    I saw your old post about your generator set-up, and thought I’d pass something along to you about how to power sensitive electronics with your generator (please forgive me if you’ve picked this up in the interim).

    By the way, your generator is listed as having an automatic voltage regulator (AVR). The AVR is supposed to hold the voltage within a certain range that should be specified by the manufacturer. The specs will also most likely give you a frequency range (perhaps 60 hertz, +/- 5%). That doesn’t mean that these two parameters will definitely stay in the specified ranges; there is more risk as the generator gets older, if it gets overloaded, and of course, if it starts to run out of gas.

    The total harmonic distortion (THD) of a generator is the factor that is most often used to determine if the power is clean enough for sensitive electronics. You can check with the manufacturer to find out how high the THD is for your generator. THD has to do with how pure the sine wave of the generator power is. The fuzzier the sine wave, the more harmonic distortion there is, and the less your electronics will like it. The recommendation you often see is that electronics should be run with a THD of no more than 5% or 6%.

    You can have an electrician or a friend with an oscilloscope (call the local ham radio club and you may find someone who is happy to use his toys on your generator power for free) look at the power under full load to see how clean it is.

    There is also a cheap and very safe alternative - an inverter hooked up to a storage battery (a 400-watt inverter costs $28). The inverter takes 12-volt DC battery power and converts it to 120-volt AC. We made it through Hurricane Irene with a 3500-watt, dirty power (no AVR) generator that gave us lights, freezer and fridges, plus three storage (marine) batteries that I normally use with a camper. We charged the batteries with the generator power, and ran computers and an analog TV through inverters with the batteries after they were charged. The storage batteries do run out of power, and at different rates depending on what you’re running with them. They will power a laptop, modem and router for a long time. A desktop computer and monitor will suck the power out of one much more quickly, as will an analog TV. If you have more than one battery, as we did, you can charge one while using the other, and have some power for electronics fairly steadily.

    I used a battery charger which drew two amps to charge the batteries.

    If you private message me, I can email you some additional information I developed on how to determine how long you can run various pieces of electronic equipment with a storage battery/inverter, depending on the capacity of the storage battery when fully charged.
  4. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,141
    Location:
    Houston, TX
    A side note about 12VDC to 120VAC Power Inverters.

    If You use a inverter that has Low Voltage Shutdown(Like most do) and are running it off of a 12Volt Battery that is Not being charged, the Battery Voltage will be around 12.5 Volts.

    That will greatly reduce the Usable Runtime that the inverter will run.

    Most Larger Inverters are designed to Be connect to an Automobile Battery, With the Motor Running so that the input Voltage is around 13.8VDC.

    Keeping some type of charger connected to the Battery will greatly increase your usable runtime, Without putting the system into Low-Voltage shutdown, That may occur when the battery reaches 11VDC.

    I am sure that you are aware of that.
  5. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,534
    Location:
    North Carolina
    Home remedies, remember when weight loss was eating a tape worm, more doctors smoked Camels than any other brand, coke was good for babies ect………
  6. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,141
    Location:
    Houston, TX
    My Mother thought that I had a Tape worm because I ate so much.

    I doubt it tho, Because the Whiskey in the Hot Toddy that my Grandmother gave me before bed would have killed any tape worm.

    I sure did sleep good.
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