Home Project FYI. Your Home Project Information and Idea Place

Help and Ideas For Your Home Remodeling Project

Home Project FYI. Your Home Project Information and Idea Place - Help and Ideas For Your Home Remodeling Project

Lightning Facts

Lightning

Lightning is the “visible discharge of static electricity within a cloud, between clouds or between the earth and a cloud,” as defined by Underwriters Laboratories. Lightning is unpredictable and a serious threat to buildings and their occupants virtually everywhere.Lightning

Facts about lightning:

  • Benjamin Franklin invented the first lightning rod in 1752 –- a kite outfitted with a metal key — while waiting impatiently for the completion of a church on top of which he would mount a lightning rod.
  • Lightning comes up from the earth –- as well as down from the cloud — from high vertical features such as chimneys and trees.
  • A typical lightning bolt carries 50,000 amps, tens of millions of volts, and can reach 50,000° F. “Superbolts” may be 100 times more powerful than typical bolts, and travel much farther, too; one such superbolt went from Waco to Dallas, Texas, after having traveled about 118 miles.
  • According to the National Weather Service, of the 34 people killed by lightning in the United States in 2009, all were outside when they were struck. Thus, homes provide a great deal of safety against lightning strikes. Interestingly, the same report indicates that 82% of lightning casualties were male.
  • Permanent injuries caused by lightning strikes are predominantly neurological and can include sleep disorders, attention deficits, numbness, dizziness, irritability, fatigue, depression, and an inability to sit for long periods of time.
  • Between 2002 and 2005, lightning caused an annual average of $213 million in property damage.

Types of dangers from lightning to houses and occupants:

  • damaged appliances from power surges;
  • electrocution risk for occupants;
  • fire risk to the building and occupants;
  • damage to the structure from water used to douse the fire by the fire department; and
  • damage to the structure and endangered health from mold colonies, if the building was not dried quickly following fire suppression.

Corrugated Stainless Steel Tubing (CSST)

CSST is a relatively new type of gas tubing that has been widely installed in houses and in commercial applications in recent years. Its small diameter makes it flexible and relatively easy to install when compared with traditional, rigid, heavy-walled pipes, although this same quality is believed to make it susceptible to fire due to lightning strikes. Lightning that travels down the CSST can burn holes in the tubing and allow gas leakage and fire. In the worst cases, gas leaks have led to disastrous gas explosions. CSST has been found to be susceptible to damage from direct and even nearby lightning strikes.

This steal pipe, made by Titeflex, is believed to contribute to fire risks following a lightning strike

These claims have lead to a class-action lawsuit against manufacturers of CCST (Titeflex, Ward, OmegaFlex and Parker Hannifin) installed in homes as of September 5, 2006. Plaintiffs claim that the CSST tubing is not thick enough to prevent becoming damaged in the event of a lightning strike, and that CSST manufacturers failed to warn consumers about such dangers. The defendants claim that CSST is safe if properly installed, in accordance with local codes and the manufacturers’ instructions. According to the Lightning Protection Institute, dangerous CSST has been installed in more than a million homes in the United States.

Identification of CSST

Typically, these products may be visible in attic spaces, along floor joists, above basements, or connected to exposed appliances, such as water heaters. The piping can be identified by its manufacturer’s mark, each of which are listed below:

  • OmegaFlex’s CSST is stamped with the marks “TRACPIPE” or “COUNTERSTRIKE.”
  • Parker Hannifin’s CSST is stamped with the mark “PARFLEX.”
  • Titeflex’s CSST is stamped with the mark “GASTITE.”
  • Ward’s CSST is stamped with the mark “WARDFLEX.”
Additional bonding to ground is recommended for houses with CSST.

Safety tips for clients during thunder and lightning storms:

  • Unplug sensitive appliances, such as computers and telephones, from electrical outlets and phone lines. Surge protectors are helpful, but they should not be relied upon during a storm.
  • Stay off corded phones, computers, and other electronic equipment that put you in direct contact with electricity. If you are unable to unplug them, turn them off. Lightning may strike nearby electric or phone lines and enter your home.
  • Unplug other appliances, such as air conditioners.
  • Stay away from windows.
  • Avoid washing your hands, bathing, doing laundry, and washing dishes — activities that put you in direct contact with running water.

Lightning Protection Systems

Lightning protection systems are devices intended to divert lightning into low-resistance paths to or from the earth and away from non-conducting parts of a structure. For specific inspection instructions regarding these systems, see the National Fire Protection Agency’s NFPA-780.

Lightning Rods

Metal rods are fastened to the building to intercept electric discharges that might otherwise strike a building component itself, such as a chimney or metal roof. Electrical discharges striking the air terminal are directed through metal conductors to a grounding system and thence into the earth.
Controversy has existed for centuries concerning whether lightning rods should have blunt or sharp tips. Recent studies have found that moderately blunt metal rods are better lightning-strike receptors than sharper rods or very blunt rods.

FYI, lightning can be very dangerous to homes and occupants, although devices and measures exist to limit this danger.

Lightning Safety Information

TumblrShare

Electrical Service Grounding Electrodes

Grounding Electrodes and UFER

Grounding electrodes systems divert potentially dangerous electrical currents by providing a path between a building’s service box
Grounding electrodes diagram and the earth. Lightning and static electricity are the most common sources of dangerous or damaging charges that can be dissipated through a grounding system. Grounding electrodes are connected to the building’s electrical system through the grounding electrodes conductors, also known as ground wires. A number of different metal alloys can function as grounding electrodes, the most common of which are the focus of this article.

Requirements for grounding electrodes and ground wires:

  • Aluminum has a tendency to corrode and should not be used in ground wires unless they are insulated. Moisture and mineral salts from masonry are common causes of corrosion to uninsulated aluminum. It is also a poorer conductor than copper. Aluminum wires in grounding electrodes are not permitted in Canada.
  • Since grounding electrodes are not insulated, they can never be made of aluminum.
  • If multiple grounding electrodes, they must be connected to each other with a bonding jumper.

Common Types of Grounding Electrodes

The most common form of grounding electrodes are metal rods that is hammered into the ground so that its entire length is submerged. The grounding electrodes should rod be inserted vertically and in one piece, but this is not always possible in rocky areas. If the grounding electrodes rod is hammered into sub-surface rocks it might become scratched and lose its cladding. Rust can accumulate on exposed iron or steel and degrade the conductive capacity of the rod. Unfortunately, this rust will rarely be visible.

 

Electricians have been known to cut the grounding electrodes rod when they have difficulty inserting its entire length beneath the ground. This practice violates code and can be a safety hazard. Look for the following signs that indicate that a grounding rod has been shortened:

  • Rust at the rod’s top. Grounding electrodes rod have a corrosion-resistant coating but are usually made of steel or iron and are vulnerable to rusting at any location that the rod is cut.
  • Most rods have an etched label on their top. If this label is missing it is likely that the rod has been cut.

Bear in mind that utility companies sometimes allow grounding electrodes ground rods to be shortened. A qualified electrician can test whether shortened rods are adequate grounding electrodes.

If accessible, check the condition of the clamp that connects the grounding electrodes grounding rod to the ground wire. Clamps should be made of bronze or copper and be tightly fastened. Requirements for grounding electrodes rod length, thickness, and protective coating are addressed in the 2006 International Residential Code (IRC) as follows:

Rod and pipe grounding electrodes not less than 8 feet (2438 mm) in length and consisting of the following materials shall be considered as a grounding electrode:

  1. Grounding Electrodes of pipe or conduit shall be not smaller than trade size ¾ (metric designator 21) and, where of iron or steel, shall have the outer surface galvanized or otherwise metal-coated for corrosion protection.
  2. Grounding Electrodes of rods of iron or steel shall be at least 5/8 inch (15.9 mm) in diameter. Stainless steel rods less than 5/8 inch (15.9mm) in diameter, nonferrous rods or their equivalent shall be listed and shall be not less than 1⁄2 inch (12.7mm) in diameter.

Grounding Electrodes Notes

  • Although the 2006 IRC does not mention whether the rod may be driven at an angle, the 1998 California Electrical Code allows for a maximum oblique angle of 45 degrees from the vertical.
  • An electrician can install two grounding electrodes rods if necessary. They should be at least 6 feet apart from one another.
  • In Canada, grounding electrodes rods should be 10 feet long and two are required.

Concrete-Encased Grounding Electrodes (Ufer Grounds)

This electrical grounding technique was invented during World War II in Arizona, and is commonly called “Ufer” after its creator, Herbert G. Ufer. The United States Army was concerned that lightning or static electricity could cause the accidental detonation of explosives that were stored in igloo-shaped vaults. The desert climate restricted the usefulness of grounding rods, which would have to be driven hundreds of feet into the dry earth in order to be effective. Ufer advised the military to connect ground wires into the concrete-encased steel reinforcement bars (re-bar) of the bomb vaults in order to dissipate electricity effectively into the ground. Testing confirmed his theory that the relatively high conductivity of concrete would allow electric current to dissipate into a large surface area of earth. The Ufer method is more common in newer residential construction and requires a metal frame. It might be difficult for an inspector to detect this type of electrode. The 2006 IRC details Ufer grounds as follows:

 

An electrode encased by at least 2 inches (51 mm) of concrete, located within and near the bottom of a concrete foundation or footing that is in direct contact with the earth, consisting of at least 20 feet (6096 mm) of one or more bare or zinc-galvanized or three electrically conductive coated steel reinforcing bars or rods of not less than 1/2 inch (12.77 mm) diameter or consisting of at least 20 (6096 mm) feet of bare copper conductor not smaller than 4 AWG shall be considered as a grounding electrode. Reinforcing bars shall be permitted to be bonded together by the usual tie wires or other effective means.

Metal Underground Water Pipes

A building’s plumbing system can be connected to the ground wire and function as a grounding electrode. For some time, this was the only mandatory grounding electrode type and it was generally preferred over other methods. As of 1987, however, this method became the only one that must be supplemented with another type of electrode. This transition is due to the increased popularity of non-conductive dielectric unions and plastic pipes. When plumbing has been replaced with plastic pipes a notice is required to be placed at the electrical service panel that states that there is a non-metallic water service. Inspectors will not be able to tell if outdoor water pipes that run to street water mains have been replaced with plastic components.

Check for the following:

  • Ground wires should be firmly attached to water pipes close to the point of entry to the building. A ground wire that is loosely tied around a pipe is inadequate.
  • Gas pipes should never be used as grounding conductors. They usually are made of plastic at the exterior of the home and carry flammable gases that may ignite if exposed to electrical current.

The 2006 IRC states the following about water pipe grounding electrodes:

A metal underground water pipe that is in direct contact with the earth for 10 feet (3048 mm) or more, including any well casing effectively bonded to the pipe and that is electrically continuous by bonding around insulating joints or insulating pipe to the points of connection of the grounding electrode conductor and the bonding conductors, shall be considered as a grounding electrode. Interior metal water piping located more than 5 feet (1524 mm) from the entrance to the building shall not be used as part of the grounding electrode system or as a conductor to interconnect electrodes that are part of the grounding electrode system.

Less Common Grounding Electrodes

The previously mentioned grounding electrodes constitute the vast majority of grounding systems that inspectors will encounter. The two electrodes described below are far less common, although they are recognized by the IRC. Inspectors might not be able to verify their presence. The 2006 IRC explains them as follows:

Plate Electrodes

A plate electrode that exposes no less than 2 square feet (0.186 m2) of surface to exterior soil shall be considered as a grounding electrode. Electrodes of iron or steel plates shall be at least 1⁄4 inch (6.4mm) in thickness. Electrodes of nonferrous metal shall be at least 0.06 inch (1.5mm) in thickness. Plate electrodes shall be installed not less than 30 inches (762 mm) below the surface of the earth.

 

Ground Ring Electrodes

A ground ring encircling the building or structure, in direct contact with the earth at a depth below the earth’s surface of not less than 2.5 feet, consisting of at least 20 feet of bare copper conductor not smaller than No. 2 shall be considered as a grounding electrode.

 

A variety of home service grounding electrodes can be used to safely route unexpected electrical charges away from places that they can cause harm. Be aware of how they differ from one another and be prepared to spot defects.

TumblrShare
SEO Powered by Platinum SEO from Techblissonline