Power Quality 101 for the homeowner

The Electric Utility Disclaimer

When it comes to power quality, most homeowners assume that the electric utility is providing clean, conditioned power for all of the hard-wired appliances and portable devices plugged into their receptacles.

In reality, most electric utilities have statements in their contract documents that say just the opposite.

They define the types of power abnormalities that might exist and even suggest additional equipment or devices that may be needed by the customer, to make the power appropriate for computers or other sensitive electronic equipment.

Their suggestions typically include the use of surge protection devices (SPDs) and uninterruptable power supplies (UPSs) among others. All of the suggested power quality improvement devices are the responsibility, and at the expense of the homeowner.

Then and Now

In the days before the proliferation of electronic devices in the home, the power quality delivered by the utility was usually adequate as delivered.

The motors, mechanical switches, relays, and tungsten filament light bulbs and resistive heating elements used in the home were quite tolerant of power quality abnormalities.

Today, almost all residential electrical products contain electronic devices of one kind or another. The electronic components used in consumer products and appliances can be destroyed by poor power quality events such as voltage surges.

Where Are Electronic Devices Used In the Home?

A new home built today is required by the National Electrical Code to have ground fault circuit interrupters (GFCIs) in locations such as kitchens, outdoors, bathrooms and basements. GFCI devices use electronic components.

In addition, arc fault circuit interrupter (AFCI) breakers are required to help prevent electrical fires in building wires or flexible cords attached to receptacles. Likewise, this device uses electronic components.

Wall-mounted light dimmers use electronic components to dim the lights.

New furnaces, boilers and thermostats have expensive, proprietary, electronic control circuit boards that are out-of-sight from the homeowner.

The point is, even if you don’t buy a single device to plug into a receptacle, your new home is already filled with sensitive electronic devices. These devices are part of the hard-wired equipment, devices, and basic code-required, home electrical infrastructure.

It’s a bit more evident at the time of purchase, that small and large home appliances are electronic in nature. In addition, computers, network devices, audio and video equipment, all add to the electronics-based equipment in the home.  Each of these items represents a significant investment to the homeowner.

Single Circuit Board Manufacturing

Many residential or consumer-marketed products are designed and built to be low-cost and sold in a highly competitive market. Low-cost products include manufacturing and component packaging methods that can include all electronic functions on a single circuit board for the product.

The manufacturer’s initial cost can be further reduced if power quality devices are eliminated from the circuit board design. Although these manufacturing methods help to reduce the initial product cost, they may subject the consumer to higher repair costs in the future, should an individual component fail.

Electronic appliances and devices with a single control board may be more economical to replace with a new unit. Repair costs for a complete circuit board replacement and labor charges can exceed the new unit price.

Many of these devices are designed to be “throw-away and replace” devices when they fail. This is why it makes sense to prevent premature end-of-life for these products.

Causes of Power Quality Problems

There are many sources of power quality abnormalities in the home. Some originate from outside the home and others occur within the home itself.

A portable window air-conditioner could create a problem for other nearby electronic devices. An old kitchen mixer can corrupt the power and affect other electronic devices.

Various power quality studies suggest that roughly 20% of surges originate from outside of the home and 80% are generated by devices within the home itself.

Protecting Your High Value Electronic Investments

The utility company states that providing clean power and protection for computers and other sensitive electronic devices are the responsibility of the homeowner. In reality, just about everything in the home today is manufactured with electronic components.

A simple LED, 60-watt equivalent, light bulb has an electronic circuit board inside. With almost all connected electrical equipment potentially at risk, why not address this risk now before you experience an unexpected — and expensive — loss?

Homeowners can help to protect their electronic investments by taking these cost-effective actions:

  • Have a licensed electrician install a UL listed, whole house surge protection device (SPD) at your main electrical panel. This device will help protect your entire electrical system from the 20% of surges that originate from outside your home. It will also help protect your expensive hard-wired equipment such as the furnace electronic control boards and electronic, variable-speed, blower motor controllers.  Be sure to regularly check the monitoring lights on the device. If the lights indicate a failed condition, it means the device needs to be replaced. Replacement will require a licensed electrician. SPDs are sacrificial devices designed to take the surge instead of your expensive equipment.
  • Install point-of-use, UL listed, surge protection devices at each high-value, electronic device that plugs into a wall receptacle. These dedicated devices will work together with the whole-house device to give the maximum protection to your electronic equipment. As with the whole house SPD, be sure to replace the unit if the monitoring lights indicate a failed condition.
  • Consider using an uninterruptible power supply (UPS) for some of your most critical electronic devices such as computers or other data-sensitive equipment. A UPS can provide battery backup power for your connected equipment in the event you lose power. UPS batteries need to be replaced periodically as recommended by the manufacturer.


© 2017 The Hartford Steam Boiler Inspection and Insurance Company. All rights reserved. This article is for informational purposes only. All recommendations are general guidelines and are not intended to be exhaustive or complete, nor are they designed to replace information or instructions from the manufacturer of your equipment. Contact your equipment service representative or manufacturer with specific questions.

John A. Weber

John Weber is principal electrical engineer for HSB. He has over 25 years’ experience in solving facilities and electrical engineering challenges.


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