Power by the Hour

Today's electrical contractors (ECs) are capitalizing on the ever-increasing opportunities presented in installing generators for residential use. Whether working with portable or stand-alone generators, there are numerous criteria to consider when installing backup power supplies.

According to David Moeller, national market manager for construction at Graybar, the first step a residential EC should take is to decide if the generator(s) will be permanent or portable. After that, he advises ECs focus on what size the unit should be.

It is the EC’s responsibility to determine which type of unit is best suited for the owner. The main types are standby and portable generators. Joe Wiegert, technical sales representative for Generac Power Systems, suggests standby generators.

“A home standby generator is the best solution for a homeowner because it is fully automatic, and everything has been set up by a professional,” Weigert said.

“In about 15 seconds after the power goes out, the automatic standby generator kicks in, and life goes on as normal,” he said. “While running, the generator continues to monitor the line for the return of utility power. As soon as it’s back on, the generator shuts off, and the house is automatically switched back to the utility.”

Portable units are much more involved for a homeowner. The main drawback of a portable generator is that the homeowner must be there when the power goes out for it to be effective. In addition, with portable units, an owner must set up, plug in, refuel and start it. This makes them more dangerous. However, in spite of the many drawbacks, portables may be the preferred choice if cost is an issue.

As the one who is helping the homeowner decide between portable and automatic, ECs must ask, “What does the homeowner want to hook up to the unit?” and “Will there be numerous appliances being hooked up or only a few?” These questions will help the EC target the right solution for the customer.

There are other things to consider, especially when it comes to whole-house backup. In this case, the generator’s size is very important. Generators should be 25 percent larger than the peak load to allow for potential additional capacity.

“With whole-house backup, the generator has to be sized correctly. When this is done, the generator will run everything in the house just as if the house was being powered by the utility,” Wiegert said.


Standby generators are installed much differently than portable ones. A portable generator installation is more straightforward. A portable generator has the appeal of being hidden away. When not in use, it can be stowed in a shed, garage or other housing outside of the home. ECs can install a standby generator in a convenient place, and installation is relatively simple.

Installation of an automatic standby generator is more complex. “To install a generator system of this type, the contractor would bring the utility wires from the meter to the main disconnect on the automatic transfer switch,” Wiegert said. “He’d then interconnect the transfer switch and the main panel, and the transfer switch and the generator. There are different types of switches to meet individual customers’ needs. So, the size of the generator, the choice of switch to be used, and the way the system is connected are all things to be considered before installing an automatic system.”

Some manufacturers are coming out with new products to make the installations for contractors go more smoothly.

“There are more and more electronic versions of switches, and a good example of this is the Square D panel and Kohler Generator electronics where there is an electronic package built in as the electronic intelligent load center,” Moeller said. “This is the newest advance, as it combines the electronic package and panel. It makes it more reliable, consistent and easier to install for the contractor as it allows maintenance data to be gathered and reported.”

The codes know best

Amid all of this, ECs must never forget safety, and that is why parts of the National Electrical Code (NEC) apply to generators. It’s also important to check UL 2200 for stationary generator assemblies, as it applies to certain jurisdictions. However, in addition to ensuring Code requirements are met when installing a generator, ECs must always follow the manufacturer’s instructions. A great first step is to check in with the town’s building and electrical inspectors.

“Some of the most important things electrical contractors should be aware of when hooking up generators is being in compliance with OSHA, speaking with the local municipality and NFPA before the electrical installation,” Wiegert said. “I tell everyone to take 15 minutes and give the inspector a call to see if there are certain requirements they may be unaware of, because each municipality is different.”

In addition to checking with the local authorities having jurisdiction, ECs should pay attention to the environments of any proposed generator site. Nelson Montgomery, chief electrical inspector for the city of Tampa, Fla., cites this concern as the most important.

“The biggest thing contractors should be aware of, especially in Florida, is to be sure the area is not in a flood plain,” Montgomery said. “They should watch for the distance from combustible materials and windows and openings in structures. They should also be aware of the distance around the generator and know the calculations for the load.”

According to Article 702.6 of the NEC, standby generators must be installed with transfer switches, which disconnect the household circuit from the utility’s side of the electrical panel to prevent backfeeding power onto the power lines, before connecting the generator to the household system.

The automatic transfer switch must be sized to disconnect the electric loads from the power supplier’s utility grid. The switch prevents the backflow of current into the utility’s lines during an outage and protects the generator from damage once the normal electric service is restored. This is the piece of equipment that allows the standby units to sense when the power goes out. It automatically starts and stops the generator as service is interrupted and restored, respectively.

“Contractors should also know if they are going to use an automatic transfer switch and show the calculated load or have an isolated panel of that area,” Montgomery said. “Most importantly, be aware of the Code requirements, so you will know what you can hook up to without overloading the generator.”

“Portable generators, however, should be used with a manual transfer switch, which should be wired to a receptacle located outside the house. The manual transfer switch can direct the generator’s power to all the circuits that set for backup. Without that transfer switch and receptacle, you have to use individual extension cords, and that can pose a safety hazard,” Wiegert said. Portable generators also pose safety hazards for homeowners, including carbon monoxide poisoning, electrocution and fire.

Truths of convenience

There is a reason backup generators exist. With all the conveniences modern technologies bring, people have less tolerance for inconvenience. Reliability is a convenience, and backup generators offer homeowners that assurance.

With growing numbers of people telecommuting, the home is becoming a more important place to be; therefore, electricity is a necessity. With the home office becoming more common in the business world, a home backup generator serves the dual purpose of a home and business generator.

“Fortunately, our economy is phenomenal, and people are spending more money. From a quality of life perception, families want to be sure their houses are warm, their electronics stay working and all systems are operational,” Wiegert said. “Auto-standby generators are popular now, too, because you could be on vacation, and there is a power failure. The freezer will still work, and the homeowner won’t be inconvenienced.

When it comes down to it, specifying a generator is dependent on the customer’s wants and needs. There is an appropriate unit for every application, but it is the EC’s job to know which unit will work best. In short, the homeowner’s electric reliability is dependent on the knowledge of the electrical contractor. EC

SPEED is a freelance writer based in Weymouth, Mass. She can be reached at 617.529.2676 or kkspeed@aol.com.



About the Author

Kellie K. Speed

Freelance Writer
Kellie Speed is a freelance writer based in Weymouth, Mass. She can be reached at 617.529.2676 or kkspeed@aol.com .

Stay Informed Join our Newsletter

Having trouble finding time to sit down with the latest issue of
ELECTRICAL CONTRACTOR? Don't worry, we'll come to you.