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Thread: generator hookup to 220 volt fuse subpanel

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    duke#1 is offline New Member
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    Cool generator hookup to 220 volt fuse subpanel

    I am going to hookup a manual transfer switch to the fuse panel in my home in case of power outages.I am in a rural area and have my own deepwell.My home was built in 1950 and so there are no grounded outlets and the main box has fuses,not breakers.From the main transmission line along the road there is a transformer,from that there are three line that come to the weatherhead and down to the meter.From the meter the three lines go into a main box with two 60 amp cigar fuses and a two blade shut-off.one wire goes to a center bar (i assume its the neutral) and the other two go to the screws that are attached to the shutoff blades.Then all three wires at the bottom of this box go through a metal pipe into the basement.All of the three wires are the same color and size.They come into the (bulldog) fuse box,one is attached to a horzontal bar and the other two go to screws at the top of a pullout main switch.in this box there are two pullouts switchs,one marked range switch and one marked main switch.Two of the wires from the outside box attach to two screws on the top of this main switch.on top of the range switch there are two screws and the two wires that attach to them go to the line that goes to the 220v stove,along with the third wire from that lie that attaches to the horizontal bar along the top.sorry to be long winded but i anted you to have the whole picture.Here's where my confusion is.There is a smaller box a few inches away from the main inside box that has a two blade shutoff,with two screw-in fuses inside it.This box has a two wire cable from the bottom of it that goes to the pressure switch on the pressure tank of the well,and two wires on the top side that goes to the inside main fuse box.Each of these two wires attach to the screws on top of the main pullout switch.This is to me what appears to be two 110 volt hot wires with no neutral.I put thetwo leads of my multi meter on these wires (one on each) and the meter reads 248 volts.the wires on my tranfer switch are supposed to hook up to these two wires I think but how can this opperate without a neutral or ground wire?

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    HayZee518's Avatar
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    ok, I'm familiar with this type of electrical connection. Your mains as you describe is the double pullout. The line side goes to the top of the double 60 cartridge fuses. the load side goes to the other pullout for your range circuit. There are two internal jumpers that feed power to the range pullout. NOW that "sidearm" disconnect. The line side you say is connected to where the mains connect in the MAIN box. This is illegal as there is NO protection for the feeders. You are the mercy of whatever is connected to these wires. Your water pump is rated at 240 volts. You don't need a neutral for a single phase 240 volt pump motor. The third wire is used as an equipment ground for short circuit to ground protection. I'll draw up a typical pullout box and the way the sidearm feeder should be connected. Just gimme a few days. I'll include the sidearm and typical porcelain fuseblocks. If by the way you're thinking of upgrading, the minimum size you can install is a 100 amp service entrance.

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    HayZee518's Avatar
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    Service entrance

    I drew up what I believe you to have - it may come close to what you described. check it out and get back to me and we'll work out what you need for a generator backup.
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    Generator backup

    For a generator backup to be foolproof if must be a double pole, double throw characteristic, being that only one side can be connected at one time. On a DPDT switch the center terminals connect to your entrance breaker. One side goes to your input from the meter, the other side which is open goes to your generator output. Reason for this, is, when you lose power and switch to the generator, once power from the power company is restored, there is NO WAY your service can be fed from two sources, I.E. the gen-set and power co. The dpdt determines either the gen-set OR the power co. ALSO utilities frown upon the possibility their lines being backfed from a live, running, gen-set.
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    Weedguy is offline New Member
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    Why is it that double-throw switches cost so darn much?

    A single breaker is relatively economical, (as is a 3 or 4-way light switch).

    I've found it really hard to find a double throw switch that isn't several hundred bucks....

    I don't blame the utilities for insisting on them; however, given that in my experience of 47 some years, there has only been on instance when I truly NEEDED a generator and if faced with it again, I will probably just throw the master breaker and use similar, "not quite code" methods to energize the house from a heavy INTERNAL branch circuit.

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    HayZee518's Avatar
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    I have the same thing as you desribe in my own house. I throw the main off then the tie breaker on and start the gen. when power is restored I shut down the gen, open the tie breaker and put the main back on.

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    HayZee518's Avatar
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    I don't know "why" they charge do much. Maybe because it isn't an assembly line product!

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    Weedguy is offline New Member
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    Worse yet- the switches often do not handle a full 200A and you get stuck as the original poster of having an "essential circuit sub-panel"

    I know it takes some extra common sense and significant, smart limitation of electrical use, but seems to me you never know when you need to turn on a light light somewhere, or where you might plug in a chest freezer in the basement....

    Thus the Hazee method (+common sense, and ALWAYS BE SURE to flip the switches in the right order)..........

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    HayZee518's Avatar
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    Weedguy - if I had a gen-set that put out 200 amps, I wouldn't even bother with a dpdt switch. I'd have enough of forsight to purchase an automatic flop-over with the means to excercise the whole machine and circuits from time to time. But for the regular homeowner who has essential circuits to work with, it's worth the bother to have the dpdt and the guys on the poles don't get fried from a backfeed. A poletop transformer backfed with 240 volts will produce 4160 volts, or at least 3900 volts - more than enough for you to call the wagon.

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    duke#1 is offline New Member
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    generator hookup

    That schematic is almost right on.The only thing is that before the lines even get to the main box inside the house there is a two blade shutoff outside on the power pole with two catridge fuses in it so that the lines coming into the house are fused already.Is that what you were talking about in your initial reply being not protected??

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