Too Much of a Good Thing Can Hurt
Your electricity and electrical appliances are so much a part of your life you hardly think about them—until there is trouble. Trouble comes in the form of power surges caused by demand fluctuations within the home (90%) and outside events such as lightning strikes, cars colliding with utility poles, limbs falling on electrical lines, etc. (10%). Any of these occurrences could cause uncontrolled electrical surges in your home’s wiring to possibly damage the appliances and electronic equipment you depend on.
A power surge can come into a home through any wire, including antenna lines, telephone wires and television cable lines. Transient surges last from nanoseconds to milliseconds. Whether the disturbance is natural or man-made, small-scale or catastrophic, today’s surge protection systems can make your equipment more dependable than ever before. UL 1449 is Underwriters Laboratories’ safety and performance standard for surge protection equipment. In August 2014, this Standard was revised to the 4th Edition. To learn more about Clamping Voltage, Joules Rating, Standards, etc., visit the Wikipedia website.
There are 2 lines of defense to prevent voltage surges from harming your home or business:
- Grounding—the first line of defense. Ensure that your home is properly grounded.
- Point-of-Use Surge Suppressors—the third line of defense. Install point-of-use/ plug-in surge protection devices to protect your sensitive electronics and digital devices. These devices can be purchased at home improvement centers, office supply stores, electronic stores, etc.
The first line of defense in protecting your equipment and appliances and ensuring their safe operation is the lowly, often forgotten, and inexpensive “Ground Rod.” This unassuming little metal rod is a key link in electrical safety and a very cost-effective insurance policy to protect your electrical equipment and appliances.
Household electrical systems are required by the National Electrical Code (NEC) to have a grounded system connected to earth ground via a ground rod. The Ground Rod is usually located very close to your main electrical service panel. The ground rod is often made of copper, or copper coated steel, approximately ½ inch in diameter or larger and 8 to 10 feet in length. It must be electrically tied to your main service panel to provide an approved ground connection.
Washington State requires the maximum resistance for a ground rod to be 25 ohms or less. If your ground rod impedance exceeds 25 ohms, additional steps must be taken to lower the impedance. Since 1990 it has been general practice to install 2 ground rods for safety.
To make a quick, visual check of your ground wire (often referred to as the grounding electrode conductor) that leads to your ground rod, go to your electric service meter. Most of these meters are installed on the outside wall of the house as near as possible to the main service panel inside the house. Toward the bottom of the wall there should be a wire coming out of the wall that is the link between the service ground connection and the ground rod. You should not see the ground rod, as it must be buried to be effective.
We have often seen ground rods not fully installed (12 inches to 18 inches or more still sticking up out of the ground), rods bent over, wire disconnected, and installed in very rocky and/or dry soil, etc. The resulting resistance in some of these cases is well in excess of 1,000 ohms. The lowest possible resistance is best and we have measured some as low as 15 ohms.
Unfortunately, we have no control over how well your electrical panel is grounded. If you do not provide proper grounding in accordance with the NEC, there is no way to mitigate electrical damage that may occur beyond your electrical panel. If you have concerns about your business or home grounding, contact a licensed electrical contractor.
Among the various situations that may occur on your electrical system, the most common are high voltage surges and damage or loss of one of the Service Conductors.
- High Voltage Surges (lightning or switching surges)—Failure to properly ground the electrical system can lead to the migration of elevated primary voltages to the premises wiring system, resulting in electric shock and/or fire due to failure of the 600 Volt insulation on the conductors.
- Damage or Loss of one of the Service Conductors—Failure to properly ground the electrical system can cause the voltage to earth during normal operation to elevate the premise wiring up to twice the normal voltage. This may be due to capacitive reactance in the circuitry, which may also stress the 600 Volt insulation on the conductors and lead to the premature failure of electrical equipment.
Another critical issue relative to sensitive electronic equipment is the proper installation and operation of Surge Protective Devices (SPD). The best surge protection equipment is much less effective without a properly installed and maintained grounding system. The SPD works by shunting damaging electrical surges away from your sensitive electronics to ground and they need the best possible ground to work properly.
It is therefore incumbent upon you to have and to maintain a NEC code-approved ground system as part of your electrical system.
NEC Code-Approved Ground System
The entire issue of grounding is covered by the National Electrical Code [NEC] in Article 250, which is under constant review and updated about every 3 years. Following is the specific language of the NEC as it pertains to this issue:
250 – 2. General Requirements for Grounding and Bonding [NEC 1999]
- Grounding of Electrical Systems. Electrical systems that are required to be grounded shall be connected to earth in a manner that will limit the voltage imposed by lightning, line surges, or unintentional contact with higher voltage lines and that will stabilize the voltage to earth during normal operation.
- Grounding of Electrical Equipment. Conductive materials enclosing electrical conductors or equipment, or forming part of such equipment, shall be connected to earth so as to limit the voltage to ground on these materials. Where the electrical system is required to be grounded, these materials shall be connected together and to the supply system grounded conductor as specified by this article. Where the electrical system is not solidly grounded, these materials shall be connected together in a manner that establishes an effective path for fault current.
- Bonding of Electrically Conductive Materials and Other Equipment. Electrically conductive materials, such as metal water piping, metal gas piping, and structural steel members, that are likely to become energized shall be bonded as specified by this article to the supply system grounded conductor or, in the case of an ungrounded electrical system, to the electrical system grounded equipment, in a manner that establishes an effective path for fault current.
- Performance of Fault Current Path. The fault current path shall be permanent and electrically continuous, shall be capable of safely carrying the maximum fault likely to be imposed on it, and shall have sufficiently low impedance to facilitate the operation of over current devices under fault conditions.
If you have concerns about your business or home grounding contact a licensed electrical contractor.
Point-of-Use Surge Suppressors
A surge protector strip attempts to limit the voltage supplied to an electric device by either blocking or by shorting to ground any unwanted voltages above a safe threshold.
Sensitive electronic equipment that should be protected by point-of-use surge protectors:
- Television, VCR, etc.
- Personal Computer
- Fax Machine & Calculator
- Home Automation System
- Stereo Equipment
- Microwave Oven
- Alarm Clock
- Electronic Telephone
- Security System
Ensure that the outlet the surge suppressor is plugged into is properly wired, with a good ground.
- Check your surge suppressor regularly to make sure it is working. If the light is out, replace the surge protector.
- Do not plug a surge suppressor into an extension cord.
- Do not plug one surge suppressor into another one.
- Do not use a surge suppressor if it smells hot or burned.
- Do not plug a surge suppressor into a circuit protected by a ground fault current interrupter (GFCI).
- You can further protect your appliances by making sure all the appliances you use on the same electrical circuit are compatible. For example, do not use your hairdryer on the same breaker or circuit as your personal computer. Because computers are so sensitive, you might want to reserve a circuit just for the computer.
Also, a battery backup system, generally referred to as a uninterruptible power supply (UPS) can provide additional in-home protection for home computers and peripheral equipment. This unit supplies power through a battery to protect against electrical outages, giving you enough time to power down the equipment safely. You may purchase a UPS in a range of configurations, depending on the amount of equipment used and the length of battery time needed.