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There's nothing like a power outage to make us realize how much we rely on electricity. Electricity powers the furnace, the refrigerator, the TV, the computers, the lighting circuits, the sump pump and, in many homes, the water well, which supplies the showers and the toilets. A prolonged power outage can leave us cold, hungry, bored, unwashed, uncomfortable and largely in the dark. And if you happen to work at home, the financial losses can quickly add up.
While an inexpensive portable generator will power the TV and a lamp or two, what's really needed is a unit that's large enough to keep a few important circuits running. The trick, though, is to connect the generator to the household wiring in a way that's safe and convenient. To do the job, we installed a manual transfer switch that routes electricity from either the municipal power supply or the generator to the vital circuits.
A manual transfer switch is actually two switches, or breakers, positioned side by side in an auxiliary panel. One breaker is powered by the main service panel and the other by the generator. Both breakers can feed power to the chosen circuits, but not at the same time. The key is a rocking toggle clip that connects both breakers so that when one is switched on, the other automatically shuts off. While both can be off, only one can be turned on at a time, which protects the generator when municipal power is restored.
A transfer switch is not automatic - you still have to flip the switch and you will have to plug in and start the generator. In this illustration, we are showing a Square D (Square D Co., 1601 Mercer Rd., Lexington, KY 40511) 4-circuit generator panel, model QO4-8M30DS-GP, which sells for about $200 in home centers, such as Lowes and Home Depot.
A large selection of transfer switches are available from Northern Tool for 6 circuit, 8 circuit or 10 circuit transfer switches. www.northerntool.com
The output of a generator is rated in watts, and this figure indicates the maximum total power draw of all the fixtures and appliances being served.
To determine the size of the generator you'll need, start by totaling the wattage of the lights and appliances on the circuits you'd like to power. Check the labels or owner's manuals for each appliance's rating. Then, add about 20 percent as a reserve to handle the increased startup power requirements of most electrical devices.
In our case, we wanted to power at least ten fixtures on two general-lighting circuits (1200 watts, when used sparingly), a sump pump (1200 watts), a refrigerator (600 watts) and the blower on our furnace (1200 watts). This gave us a practical requirement of 4200 watts with no reserve power. Knowing that in the event of a power outage, we would want to watch the news on television, be able to use our microwave, and be able to use a computer, we looked for a portable generator with a higher Watts rating.
To meet our demand, we opted for a 10,000-Watt generator (about $1,200), which provides a steady 8,000-Watts of continuous power, from Max Tool at www.maxtool.com - Model No. XP10000E.
This 16-HP unit comes with four protected AC outlets: a 20-AMP 120v standard duplex outlet, a 30-AMP Twist-Lock 120v 3-prong receptacle; a 30-amp Twist-Lock 120v/240v 4-prong receptacle; and a 50 AMP NEMA 14-50 120/240v straight 4-prong receptacle.
This generator has large air tires and strong fold away handles for moving the generator in and out of the garage, and comes with electric start and a 12-volt battery. The generator has a large capacity 5.4 gallon gas tank and will run for 10 hours at half load. A clearly visible fuel gauge is conveniently located on top of the fuel tank.
The generator has a super quiet exhaust running at Decibel level of 72 dBA, so it won't be disturbing to you or your neighbors. In addition to the electric start, it has an E-Z pull recoil start, just in case the battery should become low. The engine is also equipped with a low-oil automatic shut-off to prevent engine damage.
The super quiet muffler reduces engine noise. The Idle control holds RPM at a constant level even under heavy loads for fuel savings and noise reduction.
Installing the Transfer Switch
Because gasoline-powered generators exhaust carbon monoxide, they must be operated outdoors. Therefore, we planned to store our generator in our garage, then move it outside when needed. When selecting our generator, we looked for a generator with large stable tires and handles to make moving the generator outside an easy task.
To make the electrical connection to the panel as simple as possible, we planned the generator hookup for an outside wall of the garage near the garage door. Here we mounted a box and receptacle that is wired to the new transfer switch. We then constructed a 10-ft. extension cord to connect the generator to the outdoor receptacle.
Some local electrical codes may require that the cord to the generator be hardwired to the house electrical system. In this case a strain-relief device should be used at the connection.
Mounting the new panel
Begin by shutting off power to the main panel at its disconnect switch and removing the cover from the panel. Remember that while service panels are designed for safety, they should be approached cautiously. Even when switched off, terminals at the main disconnect will be hot and must be avoided.
With the panel exposed, break a 1-in. knockout from the side of the box and mount a short threaded nipple in the hole (Photo 1).
1--Break a knockout from the side of the service panel and install 1-in. conduit or a threaded nipple in the opening.
Connect the new switch panel to the opposite end of the nipple and anchor it to the wall with heavy screws (Photo 2).
2--Connect the new transfer switch panel to the other end of threaded nipple and secure the panel to the wall with screws.
The grounding bus for the new panel comes uninstalled and there are three locations where you can secure it. Use screws to mount the grounding bus in the position that's most convenient for you (Photo 3).
3--Install the new panel's grounding bus in one of three prepared locations. Choose the one that's most convenient.
Wiring the panels
Use an insulated screwdriver to remove the hot wire (black) from each breaker that controls a circuit you intend to power with the generator.
4--Disconnect the target circuits by first loosening the terminal screw on each breaker. Then, pull wires free.
Then, pry the breakers from the panel (Photo 5).
5--With hot wires disconnected, carefully pry each circuit breaker from its slot on the panel's hot bus.
Carefully identify the neutral (white) and grounding wires (bare) from each circuit, loosen their binding screws and pull them free (Photo 6).
6--Identify the neutral and grounding wires of each circuit. Loosen the screws that secure them to the bus.
With all the wires disconnected, separately tape together each circuit's hot, neutral and ground wires (Photo 7).
7--To prevent confusion, isolate the three wires from each circuit and separately tape each group together in the main panel.
Next, feed 10/4 cable through the pipe nipple (Photo 8). and strip the sheathing from both ends. If you wish, you can use individual 10-ga. insulated wires coded red, black, white and green in place of the cable.
8--Begin wiring the new panel by pulling 10/4 cable through pipe nipple. Strip sheathing from both ends.
Connect the neutral and grounding wires to the main panel's neutral bus (Photo 9). If your panel has a dedicated grounding bus, bind the grounding wire to the grounding bus and the neutral wire to the neutral bus.
9--Secure the neutral (white) and ground (bare) wires to the appropriate bus bar in the main panel.
To complete the connections in the main panel, attach the incoming red and black hot wires to a 30-amp, 240v breaker or a 50-amp, 240v breaker if your generator has a 50-amp 240v outlet (Photo 10)...
10--Connect the black and red hot wires of the 10/4 cable to the terminals of a 30-amp, 240v breaker or a 50-amp, 240v breaker if your generator has a 50-amp 240v outlet.
...and press the new breaker onto the panel's hot bus (Photo 11). Remove any breakers stranded at the bottom of the panel and move them up beneath the new 240v breaker.
11--To install the breaker, hook its base over the panel's retainer clip. Press until breaker seats over the bus tabs.
The connections in the side panel are nearly identical to those in the main panel. Bind the feed line's grounding wire under a grounding bus terminal (Photo 12). Then, connect the red and black wires to one of the panel's 240v breakers and attach the white neutral wire to the neutral bus near the top of the panel. At this point, the main panel is equipped to power the side panel.
To bring the disconnected circuits in the main panel to the new side panel, the wires must be extended. Codes may vary in this regard. Some local codes, like ours, allow twist connectors to be used inside the main panel, while others may require that you pull all disconnected circuit cables from the main panel and re-route them into the transfer switch.
In this case, if the circuits going to the transfer switch are not long enough, then you will be required to use junction boxes to splice additional lengths of wire onto the circuits that are not long enough to reach the terminal strips inside the transfer switch.
12--Secure the bare ground wire from the 10/4 cable to the grounding bus in new transfer switch panel.
To extend the circuits within the main panel, bring insulated wires (black, white and green) through the connecting nipple, strip about 5/8 in. of insulation from each and join the new wires to the existing circuit wires with twist connectors (Photo 13). When you're done, tuck the wires neatly against the outer edges of the panel, away from the breakers.
13--To extend circuits, connect wires from new panel to disconnected circuit wires with twist connectors.
In the side panel, attach the white neutrals to the neutral bus terminals (Photo 14) and the grounding wires to the grounding bus.
14--In the new panel, bind the extended ground (green) and neutral (white) circuit wires to the appropriate bus bar.
Then, connect each circuit's black wire to a breaker in the side panel (Photo 15).
15--To complete the connection at the side panel, secure each black circuit wire to a 120v breaker.
All that remains is to install 10/4 cable that connects the new panel to the outdoor receptacle that serves as a hookup for the generator. In our case, we brought the cable out of the top right corner of the panel (See Picture Below), then up the basement wall and through the house rim joist a few feet from the garage door.
Begin by mounting a 3/4-in. box connector in the top side of the panel, then run the 10/4 cable into the panel through this connector.
Staple the cable to the wall above the box, within 8 in., strip the cable inside the box and tighten the box connector (Photo 16). Attach the red and black hot wires to the remaining 240v breaker in the transfer switch panel and join the neutral and hot wires to their buses.
Fill any open slots in the main panel's cover with plastic blanks available at home centers and electrical supply houses. The side panel comes with adhesive labels marked generator supply and utility supply. Stick these labels in place above the appropriate breakers of the transfer switch.
Follow by labeling each circuit thats been rerouted from the main panel, now on the side panel, such as Kitchen, Living Room, Dinning Room, Furnace, Sump Pump, Basement, Master Bedroom, Central Air Conditioning, etc.
16--Feed 10/4 cable through a 3/4-in. box connector at top of side panel. Tighten connector to secure the cable.
When an outage occurs, you simply flip the switches from utility supply to generator supply, to provide temporary power from your generator.
When utility power has been restored, shut off your generator, unplug your cable and move your generator back into the garage. Then flip the switches back from generator power to utility power.
Connecting the generator
To install the generator hookup, first bore a 1 1/16-in. hole through the rim joist and pull the 10/4 cable through this opening. Then, thread a 3/4-in. galvanized nipple into the back of a weather-tight exterior box (Photo 17), feed the cable through this nipple and screw the box to the wall. To protect the siding, carefully caulk around the perimeter of the box. With the box installed, cut the cable to length and strip the sheathing from the last 8 in. Then install a flanged power inlet in the box. We suggest a Hubbell inlet, NEMA L14-30P for 30-AMP or a NEMA 14-50P for 50-AMP. This is nothing more than a male plug instead of a female receptacle.
17--Thread a 3/4-in. nipple into the outdoor receptacle box. Insert the nipple through hole in the rim joist.
A variety of flanged inlets are available for this situation, but it makes sense to choose one exactly like the one on the generator. This not only simplifies the selection process, but it assures a compatible prong configuration and load rating. Attach the red and black hot wires to the inlet's brass terminal screws, the white neutral wire to its silver terminal and the green grounding wire to the green terminal.
The extension cord we built has a male plug on one end and a female plug on the other. Make it with 10 ft. of rubber, water-resistant 10/4 cord with stranded wires. Strip 1 1/2 in. of sheathing from each end of the cord. Then, strip 1 1/16 in. of insulation from each wire. Slide the wires into the color-coded terminal slots on the plugs and tighten the terminal screws (Photo 18). Again, the red and black wires go to the brass-colored terminals, white goes to silver and green to green.
18--Secure extension cord wires to plugs. Attach hot wires to brass screws, white to silver screw and green to green.
With the cord made up, turn the transfer switch to generator supply and plug one end of the cord into the house-mounted flanged inlet. Plug the other end in the generator (Photo 19). For safety, always make sure to plug the cord into the house receptacle and into the generator before starting the generator. And, of course, always shut off the generator before unplugging either end of the extension cord.
19--Move the generator outside and plug the other end of cord into the appropriate receptacle. Then start the generator.
The generator in the above pictures are shown only for illustration, representing that the generator must be outdoors when running.
Pictures of our generator, before going outside, are shown below with a typical power cable and multi outlet adapter attached to the control panel.
Note: The above transfer switch installation is shown as an exposed installation. The procedure is the same for an in-wall installation, except the main breaker box and transfer switch are mounted flush as shown below.
Other considerations and suggestions
In some cases, where you may prefer to leave your generator outside, you should provide some extended weather protection for your generator and secure your generator to prevent theft.
Shown below are some pictures, illustrating a method as to how you may want to protect your generator, in an outside enviroment. The box below is an attractive outdoor garbage box sold at Lowes and Home Depot. Other Home and Garden supply stores also carry this box.
Install a good anchor to tie down your generator to prevent theft. This illustration shows a heavy duty eye-screw with a large hitching ring, generally used in a stable to hitch a horse. These hitching rings are available at most local hardware stores or can be ordered online at www.countrysupply.com
Inside the box, wrap a strong steel cable around the frame of your generator and lock the cable ends with a stong lock. Use a lock that requires a key. I would not use a combination lock. Combination locks require getting down on your knees and trying to rotate the dial to the correct numbers. This may be difficult to get close enough to see the numbers and may be uncomfortable. Most Master brand locks are available at your local hardware store.
Generators, Transfer Switches, Cables, Cords and Plugs
You can shop till you drop, when looking to buy a generator. There are several brands and several wattage sizes. In my case, I wanted the most wattage and the best price. I shopped for nearly a year before I found what I was looking for. I am very pleased with my purchase of a 10,000 Watt generator, I bought from Max Tool. I had looked at more than forty portable generators before I made my decision.
I got 10,000 watts of power, handles with wheels and air tires, 5.4 gallon fuel tank that will run for up to 10 hours, one 30-AMP 125v connector, one 30-AMP 125v/250v connector, one 50-AMP 125v/250v connector, one 20-AMP duplex 125v connector, a 12-volt outlet, automatic "low-oil" shutoff, control panel power meter, electric key start and it came with a battery, and a warranty.
I would recommend Max Tool as my first choice to anyone looking to buy a generator. Next, I would recommend a 10,000 watt generator from Northern Tool. The Northern Tool generator is about twice the price of Max Tool.
The Northern Tool 10,000 watt generator does run one hour longer than the Max Tool generator, but it uses nearly twice the amount of fuel. The Northern Tool generator does not come with handles, wheels or tires. It does come with electric start, but does not come with a battery. You have to pay extra for these items with a Northern Tool generator.
Listed below you will find generators, power cables, plugs, adapters and transfer switches. All items have links to stores where you can view and purchase these items online.
When deciding what transfer switch will work best for your home, it's best to consider a 50-AMP design. Even if you start out with a small generator with a 30-AMP power cord, you will have the ability of upgrading to a larger generator, without the expense and labor costs of changing out the wiring and installing a 50-AMP transfer switch.
Even if your generator only has a 30-AMP connector, you can use a 50-AMP cable. You will need to change the 50-AMP male connector end of the cable, to a 30-AMP male plug. Then save the 50-AMP male plug for when you upgrade to a larger generator that has a 50-AMP outlet.
The difference in cost of a generator with a 30-AMP and a generator that has both 30-AMP and 50-AMP outlets does not cost a fortune. During a power outage, you want your home to operate as normal as possible. It's better to have more power than you need, than not having enough.
In calculating your power requirements, keep in mind the basic things you want to operate during a power outage. Also figure on a few additional items, such as a Microwave, Television, Computer, Cordless Phone, etc. Listed below are household items with typical watts requirements.
In our case, we wanted to power at least ten fixtures on two general-lighting circuits (1200 watts, when used sparingly), a sump pump (1200 watts), a refrigerator (600 watts) and the blower on our furnace (1200 watts). This gave us a practical requirement of 4200 watts with no reserve power.
Knowing that in the event of a power outage, we would want to watch the news on television (300 watts), be able to use our microwave (1500 watts), and be able to use a computer (750 watts). We also wanted to keep our freezer running (500 watts), so we looked for a portable generator with a higher Watts rating of at least 7,250 watts.
In surge watts we considered our sump pump at 4100 surge-watts, refrigerator at 2000 surge-watts, our furnace at 2300 surge-watts, our freezer at 1000 surge-watts, with six light bulbs turned on (100-watt each) at 600 surge-watts. This gave us a total of 10,000 surge-watts at the time when the generator would be powered up.
This brings up an important point. When powering up your generator, turn off the breakers in the transfer switch. Once you have the generator running, then start turning on the breakers in the transfer switch, one at a time. This will reduce the strain on the generator and lower the requirement for a large amount of surge-watts, all at one time.
Completed installation with generator connected to the outside inlet box.
Illustration of connecting generator directly to the transfer switch.
The garage door is open for illustration. The generator must be outside and the garage door must be closed when the generator is running.