10 Oct

Acid Rain

Acid Rain and Inspectors: Buildings at Risk

by Nick Gromicko and Kate Tarasenko

“Acid rain,” like “global warming,” is a phenomenon whose very existence is disputed by some. In fact, evidence of acid rain has been observed in industrialized cities around the world since the mid-1800s. “Acid rain” describes the mixture of wet and dry deposits from the atmosphere which contain high amounts of nitric and sulfuric acids that result from both natural and man-made emissions. Its effects on structures and homes are very real. Inspectors can learn more about acid rain and its destructive signs on metal and stone components of the exteriors of homes.

Acid rain is formed when the chemical precursors of nitric and sulfuric acids — sulfur dioxide (SO₂) and nitrogen oxide (NO_x), respectively — combine with natural sources of acidic particles, such as volcanoes and decaying vegetation. When this mixture reacts with oxygen, water and other chemicals (including pollutants such as carbon dioxide), the result is acid rain, which can be carried by rain, and even snow, frost, fog and mist, which, in turn, runs off into soil and groundwater.

According to the EPA, about two-thirds of all SO₂ and one-quarter of the NO_x emissions in the atmosphere in the U.S. result from power plants that burn fossil fuels (primarily coal), as well as vehicles and agricultural equipment that rely on gasoline.

It is fair to say that any industrialized region with power plants that burn fossil fuels will show some wear on its surrounding structures from acid rain. But buildings in arid regions are at greater risk because of dry deposition, in which acidic pollutants are present in gases, smoke and dust, which tend to stick to buildings, cars and other structures. When it rains or snows, the subsequent wet deposition of nitric and sulfuric acids becomes even more acidic, which then washes into the soil and aquifers.

The more obvious impacts of acid rain can be seen on particular types of stone, such as limestone and marble buildings, monuments, statues and headstones.

The weathering pits and canyons can obliterate the lettering and features of such structures to a brutal degree, depending on the type of stone and other environmental conditions.

Acid rain can also corrode bronze and other metals, such as nickel, zinc, copper, and carbon-steel, as evidenced by streaks and discoloration on bridges and other metal structures, such as many commercial buildings.

Not all buildings or structures suffer the effects of acid rain. How big of a threat it is can be determined by the chemical makeup and interactions of a building’s materials. Limestone and marble, which, historically, were used widely because of their availability and workability by artisans, are especially susceptible because they are composed of calcite, or calcium carbonate, which acidic chemicals can dissolve easily. To observe this first-hand, drop a piece of blackboard chalk into a glass of vinegar. Drop another piece of chalk into a glass of water. The next morning, you’ll see the alarming difference.

Modern buildings tend to use granite, which is composed of silicate minerals, such as quartz and feldspar. Silicate minerals resist acidic attacks from the atmosphere. Sandstone, another silica material, is also resistant. Stainless steel and aluminum tend to hold up better. But all minerals, including those found in paint and road overlay, are affected, to some degree.

Because of the switchover in the use of certain building materials in the post-Industrial Era, historic buildings, more so than modern ones, tend to show the destructive outcome of acid rain since we first began burning fossil fuels for energy. London’s Westminster Abbey, the Colosseum in Rome, and India’s Taj Mahal all show signs of degradation brought on by atmospheric nitric and sulfuric acids.

Plant life and wildlife are also affected. The pH — or alkalinity and acidity — of lake water, for example, tends to re-stabilize and maintain equilibrium when contaminated by acid rain. However, soil and trees can become irreparably harmed when their pH is disturbed to the extent that their natural abilities to compensate for chemical fluctuations in the environment are thwarted. Soil contains naturally occurring mercury and aluminum, which are normally poisonous for plant life. But plants can survive when the nutrient base of the soil remains healthy, giving them a strong buffering capacity. Acid rain, however, destroys the environmental balance, and these naturally occurring chemical threats suddenly become fatal. The plants’ “immune systems,” made stronger by the surrounding soil, become compromised. The plants and trees may die a slow death due to nutrient starvation, oxygen deprivation, injured leaves that cannot recover, and/or their bark will become damaged and vulnerable to mold, fungi and wood-destroying insects.

When the environment is under continual attack by the deadly effects of acid rain, the odds of survival for other resident plant, animal and insect species diminish as the ecosystem is thrown out of its natural balance.

On the flipside, NASA researchers recently discovered that one species of swampland bacteria’s ability to produce methane — a greenhouse gas that contributes to global warming — is actually inhibited by acid rain.

The EPA’s Acid Rain Program got underway in 1995 (after being enacted by Congress in 1990), which continues to seek to reduce SO₂ and NO_x emissions to below 1980 pollution levels. The program originally targeted coal-burning electricity plants, and has expanded to include other types of industry that burn coal, oil and gas, too. While the EPA touts some success in bringing down some polluters’ output by 40%, critics charge that because the program permits emission “allowance trading” among its participants, the larger industrial polluters simply pay the $2,000-per-ton fine for exceeding SO₂ and NO_x limits. The EPA, however, has embraced a market-friendly approach while shooting for overall target reductions.

The primary problem with acid rain, of course, is that there is no way to contain it. It blows with the wind and is captured and carried by localized weather systems. Although the deterioration which acid rain causes may be slow, it is persistent. And until we shift our reliance on fossil fuels by using various types of green energy (wind, solar, etc.), we will continue to witness the destructive consequences in all aspects of our environment, both natural and man-made, for decades to come.

Homeowners can mitigate the environmental effects of acid rain by modifying their purchasing and traveling habits, and by using building materials that are better able to withstand the corrosive effects of this modern scourge. Inspectors can become more familiar with the problems posed by acid rain by investigating the types of building materials used, and by contacting their local EPA representative for up-to-date statistics on pollution levels for their specific area.

10 Oct

Mold Remediation

Abrasive Blasting for Mold Remediation

by Nick Gromicko and Ethan Ward

Mold in the Home

Health concerns related to the growth of mold in the home have been featured heavily in the news. Problems ranging from itchy eyes, coughing and sneezing to serious allergic reactions, asthma attacks, and even the possibility of permanent lung damage can all be caused by mold, which can be found growing in the home, given the right conditions.

All that is needed for mold to grow is moisture, oxygen, a food source, and a surface to grow on. Mold spores are commonly found naturally in the air. If spores land on a wet or damp spot indoors and begin growing, they will lead to problems. Molds produce allergens, irritants and, in some cases, potentially toxic substances called mycotoxins. Inhaling or touching mold or mold spores may cause allergic reactions in sensitive individuals. Allergic responses include hay fever-type symptoms, such as sneezing, runny nose, red eyes, and skin rash (dermatitis). Allergic reactions to mold are common. They can be immediate or delayed. Molds can also trigger asthma attacks in people with asthma who are allergic to mold. In addition, mold exposure can irritate the eyes, skin, nose, throat and lungs of both mold-allergic and non-allergic people.

As more is understood about the health issues related to mold growth in interior environments, new methods for mold assessment and remediation are being put into practice. Mold assessment and mold remediation are techniques used in occupational health. Mold assessment is the process of identifying the location and extent of the mold hazard in a structure. Mold remediation is the process of cleanup and/or removal of mold from an indoor environment. Mold remediation is usually conducted by a company with experience in construction, demolition, cleaning, airborne-particle containment-control, and the use of special equipment to protect workers and building occupants from contaminated or irritating dust and organic debris. A new method that is gaining traction in this area is abrasive blasting.

Abrasive Blasting

The first step in combating mold growth is not to allow for an environment that is conducive to its growth in the first place. Controlling moisture and assuring that standing water from leaks or floods is eliminated are the most important places to start. If mold growth has already begun, the mold must be removed completely, and any affected surfaces must be cleaned or repaired. Traditional methods for remediation have been slow and tedious, often involving copious amounts of hand-scrubbing and sanding. Abrasive blasting is a new technique that is proving to be less tedious and time-consuming, while maintaining a high level of effectiveness.

Abrasive blasting is a process for cleaning or finishing objects by using an air-blast or centrifugal wheel that throws abrasive particles against the surface of the work pieces. Sand, dry ice and corncobs are just some of the different types of media used in blasting. For the purposes of mold remediation, sodium bicarbonate (baking soda) and dry ice are the media commonly used.

Benefits of Abrasive Blasting

Abrasive (or “media”) blasting provides some distinct advantages over traditional techniques of mold remediation. In addition to eliminating much of the tedious labor involved in scrubbing and sanding by hand, abrasive blasting is extremely useful for cleaning irregular and hard-to-reach surfaces. Surfaces that have cross-bracing or bridging can be cleaned more easily, as well as areas such as the bottom of a deck, where nails may be protruding. Areas that are difficult to access, such as attics and crawlspaces, can also be cleaned more easily with abrasive blasting than by traditional methods. The time saved is also an advantage, and the typical timeframe for completion of a mold remediation project can often be greatly reduced by utilizing abrasive blasting.

Soda-Blasting

Soda-blasting is a type of abrasive blasting that utilizes sodium bicarbonate as the medium propelled by compressed air. One of the earliest and most widely publicized uses of soda-blasting was on the restoration of the Statue of Liberty. In May of 1982, President Ronald Reagan appointed Lee Iacocca to head up a private-sector effort for the project.

Fundraising began for the $87 million restoration under a public-private partnership between the National Park Service and The Statue of Liberty-Ellis Island Foundation, Inc. After extensive work that included the use of soda-blasting, the restored monument re-opened to the public on July 5, 1986, during Liberty Weekend, which celebrated the statue’s centennial.

The baking soda used in soda-blasting is soft but angular, appearing knife-like under a microscope. The crystals are manufactured in state-of-the-art facilities to ensure that the right size and shape are consistently produced. Baking soda is water-soluble, with a pH near neutral. Baking-soda abrasive blasting effectively removes mold while minimizing damage to the underlying surface (i.e., wood, PVC, modern wiring, ductwork, etc.). When using the proper equipment setup (correct nozzles, media regulators, hoses, etc.) and technique (proper air flow, pressure, angle of attack, etc.), the process allows for fast and efficient removal of mold, with a minimum of damage, waste and cleanup. By using a soda blaster with the correct-size nozzle, the amount of baking soda used is minimized. Minimal baking soda means better visibility while working, and less cleanup afterward.

Dry-Ice Blasting

Dry ice is solidified carbon dioxide that, at -78.5° C and ambient pressure, changes directly into a gas as it absorbs heat. Dry ice pellets are made by taking liquid carbon dioxide (CO₂) from a pressurized storage tank and expanding it at ambient pressure to produce snow. The snow is then compressed through a die to make hard pellets. The pellets are readily available from most dry ice suppliers nationwide. For dry-ice blasting, the standard size used is 1/8-inch, high-density dry ice pellets.

The dry-ice blasting process includes three phases, the first of which is energy transfer. Energy transfer works when dry ice pellets are propelled out of the blasting gun at supersonic speed and impact the surface. The energy transfer helps to knock mold off the surface being cleaned, with little or no damage.

The freezing effect of the dry ice pellets hitting the mold creates the second phase, which is micro-thermal shock, caused by the dry ice’s temperature of -79º C, between the mold and the contaminated surface. This phase isn’t as much a factor in the removal of mold as it is for removing resins, oils, waxes, food particles, and other contaminants and debris. For these types of substances, the thermal shock causes cracking and delaminating of the contaminant, furthering the elimination process.

The final phase is gas pressure, which happens when the dry ice pellets explode on impact. As the pellets warm, they convert to CO₂ gas, generating a volume expansion of 400 to 800 times. The rapid gas expansion underneath the mold forces it off the surface.

HEPA Vacuuming

A HEPA vacuum is a vacuum cleaner with a high-efficiency particulate air (or HEPA) filter through which the contaminated air flows. HEPA filters, as defined by the U.S. Department of Energy’s standard adopted by most American industries, remove at least 99.97% of airborne particles that are as small as 0.3 micrometers (µm) in diameter. HEPA vacuuming is necessary in conjunction with blasting for complete mold removal.

While abrasive blasting with either baking soda or dry ice is an effective technique, remediation will not be complete until HEPA filtering or vacuuming has been done. Abrasive blasting removes mold from contaminated surfaces, but it also causes the mold spores to become airborne again. The spores can cover the ground and the surfaces that have already been cleaned. So, the mold spores need to be removed by HEPA filters. Additionally, while some remediation companies claim that there will be no blasting media to remove after cleaning, especially with the dry-ice method, there will be at least a small amount of visible debris left by the blasting that must be removed before HEPA vacuuming can occur. HEPA vacuuming removes all invisible contaminants from surfaces and the surrounding air. When HEPA vacuuming is completed, samples at the previously contaminated areas should be re-tested to ensure that no mold or mold spores remain.

Abrasive blasting using dry ice or baking soda, combined with HEPA-filter vacuuming, is an effective method for mold remediation. InterNACHI inspectors who offer ancillary mold inspection services should be aware of the benefits and applications of this technique adapted for remediating mold in homes.

13 Aug

Knob-and-Tube Wiring

by Nick Gromicko, Rob London and Kenton Shepard

Knob-and-tube (K&T) wiring was an early standardized method of electrical wiring in buildings, in common use in North America from about 1880 to the 1940s. The system is considered obsolete and can be a safety hazard, although some of the fear associated with it is undeserved.

InterNACHI inspectors should always disclaim knob-and-tube wiring during their inspections.

Facts About Knob-and-Tube Wiring:

It is not inherently dangerous. The dangers from this system arise from its age, improper modifications, and situations where building insulation envelops the wires.
It has no ground wire and thus cannot service any three-pronged appliances.
While it is considered obsolete, there is no code that requires its complete removal.
It is treated differently in different jurisdictions. In some areas, it must be removed at all accessible locations, while others merely require that it not be installed in new construction. Inspectors should be sure to know the codes in the jurisdictions in which they operate.
It is not permitted in any new construction.

How Knob-and-Tube Wiring Works:

K&T wiring consists of insulated copper conductors passing through lumber framing drill-holes via protective porcelain insulating tubes. They are supported along their length by nailed-down porcelain knobs. Where wires enter a wiring device, such as a lamp or switch, or were pulled into a wall, they are protected by flexible cloth or rubber insulation called “loom.”

Advantages of Knob-and-Tube Wiring:

K&T wiring has a higher ampacity than wiring systems of the same gauge. The reason for this is that the hot and neutral wires are separated from one another, usually by 4 to 6 inches, which allows the wires to readily dissipate heat into free air.
K&T wires are less likely than Romex cables to be punctured by nails because K&T wires are held away from the framing.
The porcelain components have an almost unlimited lifespan.
The original installation of knob-and-tube wiring is often superior to that of modern Romex wiring. K&T wiring installation requires more skill to install than Romex and, for this reason, unskilled people rarely ever installed it.

Problems Associated with K&T Wiring:

Unsafe modifications are far more common with K&T wiring than they are with Romex and other modern wiring systems. Part of the reason for this is that K&T is so old that more opportunity has existed for improper modifications.
The insulation that envelopes the wiring is a fire hazard.
It tends to stretch and sag over time.
It lacks a grounding conductor. Grounding conductors reduce the chance of electrical fire and damage to sensitive equipment.
In older systems, wiring is insulated with varnish and fiber materials that are susceptible to deterioration.

Compared with modern wiring insulation, K&T wiring is less resistant to damage. K&T wiring insulated with cambric and asbestos is not rated for moisture exposure. Older systems contained insulation with additives that may oxidize copper wire. Bending the wires may cause insulation to crack and peel away.

K&T wiring is often spliced with modern wiring incorrectly by amateurs. This is perhaps due to the ease by which K&T wiring is accessed.

Building Insulation:

K&T wiring is designed to dissipate heat into free air, and insulation will disturb this process. Insulation around K&T wires will cause heat to build up, and this creates a fire hazard. The 2008 National Electrical Code (NEC) requires that this wiring system not be covered by insulation. Specifically, it states that this wiring system should not be in…

hollow spaces of walls, ceilings and attics where such spaces are insulated by loose, rolled or foamed-in-place insulating material that envelops the conductors.

Local jurisdictions may or may not adopt the NEC’s requirement. The California Electrical Code, for instance, allows insulation to be in contact with knob-and-tube wiring, provided that certain conditions are met, such as, but not limited to, the following:

A licensed electrical contractor must certify that the system is safe.
The certification must be filed with the local building department.
Accessible areas where insulation covers the wiring must be posted with a warning sign. In some areas, this sign must be in Spanish and English.
The insulation must be non-combustible and non-conductive.
Normal requirements for insulation must be met.

Modifications:

When K&T wiring was first introduced, common household electrical appliances were limited to little more than toasters, tea kettles, coffee percolators and

clothes irons. The electrical requirements of mid- to late-20^th century homes

could not have been foreseen during the late 18^th century, a time during which electricity, to many, was seen as a passing fad. Existing K&T systems are notorious for modifications made in an attempt to match the increasing amperage loads required by televisions, refrigerators, and a plethora of other electric appliances. Many of these attempts were made by insufficiently trained handymen, rather than experienced electricians, whose work made the wiring system vulnerable to overloading.

Many homeowners adapted to the inadequate amperage of K&T wiring by installing fuses with resistances that were too high for the wiring. The result of this modification is that the fuses would not blow as often and the wiring would suffer heat damage due to excessive amperage loads.
It is not uncommon for inspectors to find connections wrapped with masking tape or Scotch tape instead of electrical tape.

K&T Wiring and Insurance:

Many insurance companies refuse to insure houses that have knob-and-tube wiring due to the risk of fire. Exceptions are sometimes made for houses where an electrical contractor has deemed the system to be safe.

Advice for those with K&T wiring:

Have the system evaluated by a qualified electrician. Only an expert can confirm that the system was installed and modified correctly.
Do not run an excessive amount of appliances in the home, as this can cause a fire.
Where the wiring is brittle or cracked, it should be replaced. Proper maintenance is crucial.
K&T wiring should not be used in kitchens, bathrooms, laundry rooms or outdoors. Wiring must be grounded in order to be used safely in these locations.
Rewiring a house can take weeks and cost thousands of dollars, but unsafe wiring can cause fires, complicate estate transactions, and make insurers skittish.
Homeowners should carefully consider their options before deciding whether to rewire their house.
The homeowner or an electrician should carefully remove any insulation that is found surrounding K&T wires.
Prospective home buyers should get an estimate of the cost of replacing K&T wiring. They can use this amount to negotiate a cheaper price for the house.

In summary, knob-and-tube wiring is likely to be a safety hazard due to improper modifications and the addition of building insulation. Inspectors need to be wary of this old system and be prepared to inform their clients about its potential dangers.

13 Aug

How to Determine the Age of a Building

by Nick Gromicko and Rob London

Building technologies and fashions have followed well-known trends that allow inspectors, clients and anyone else interested to roughly determine Crude, square nails may be hundreds of years old

Crude, square nails may be hundreds of years old

when particular buildings were constructed. Here are some methods based on a building’s materials, components and styles.

Estimates of Building Age Based on Building Materials

Nails

Prior to the 1800s, nails were hand-made by blacksmiths and nail makers and appear crude compared with modern nails. They are often squared rather than rounded, and have a beaten look on the top of the head.
Type A- and Type B- cut nails were used from 1790 to 1830. They were made from wrought iron and are squared.
Wire nails, used from 1890 through today, are modern, machine-made nails that are rounded and more practical to use than the earlier designs.

Wiring

Aluminum wiring was used extensively from 1967 till 1975, a period during which copper was prohibitively expensive. Aluminum use was generally discontinued when its potential as a fire hazard become publicized.
K&T or knob-and-tube wiring was an early method of electrical wiring installed in buildings from 1880 to the 1940s. The system is considered obsolete and can be a fire hazard, although much of the fear associated with it is exaggerated.

Electrical Receptacles Modern electrical receptacles are polarized and grounded

Electrical receptacles evolved from earliest to most recent in the following order:

non-polarized: These early receptacles are made up of two slots of equal size, with no ground slot.
polarized: These receptacles are two-slotted, one of which is wider than the other to allow for proper polarity.
grounded, polarized: Modern receptacles were changed to permit grounding of an appliance or device. They can be identified by the round hole beneath the center of the polarized slots.

Flooring

In the late 19^th century (1890), linoleum became common for use in hallways and passages, but it became better known for its use in kitchen floors in the 20^th century, up through 1960. Originally valued for its water-resistance and affordability, it was surpassed by other floor coverings by the mid-20^thcentury.
Asphalt tile was used for floor tiles starting around 1920 through the 1960s. The earliest tiles are darker because they contained more asphalt, unlike later tiles that had higher levels of synthetic binders.
Vinyl asbestos tiles became popular in response to consumers who wanted lighter-colored tiles of varying color patterns.

Structural Panels

Plywood’s use began around 1905. It is made from thin sheets of veneer (layers of wood that are peeled from a spinning log) that are cross-laminated and glued together with a hot press. Since it is made from whole layers of logs rather than small strands, plywood has a more consistent and less rough appearance than oriented strand board (OSB).
Waferboard or particle board was developed in the 1970s and, like plywood, is still used today. This material appears similar to OSB, except the wooden strands from which it is composed are not aligned.
OSB was developed the 1980s and is manufactured from heat-cured adhesives, and then rectangularly shaped wood strands that are arranged in cross-oriented layers. Produced in large, continuous mats, OSB is a solid-panel product of consistent quality with few voids and gaps. While OSB was developed fairly recently, it became more popular than plywood in North America by 2000.

Keep in mind that houses, especially older ones, have evolved over many years. It can be very difficult to reliably date a building based on the presence of a single material or component. The majority of a house might be newer than its 18^thcentury foundation, for instance, especially if there was a fire that destroyed the rest of the structure.

Estimates of Building Age Based on Architectural Style

American Colonial (1600 to 1800): North America was colonized by Europeans who brought with them building styles from their homelands. This broad category includes the following regional styles and their characteristics:
- New England style (1600 to 1740): These homes feature steep roofs and narrows eaves used in simple timber-frame houses, usually located in the northeastern United States, primarily in Massachusetts, Vermont, Connecticut, New Hampshire and New York.
- German (1600 to 1850): Most often found in New York, Pennsylvania, Ohio and Maryland, these buildings generally feature thick, sandstone walls.
- Spanish (1600 to 1900): Located in the American South, Southwest, and California, these houses are simple and low, built from rocks, stucco, coquina and adobe brick, with small windows and thick walls.
- Other home styles from the American Colonial period include Georgian, Dutch, French and Cape Cod.

Classical style houses (1780 to 1860): Many houses built during the founding of the United States are a throwback to ancient Greece, emphasizing order and symmetry. Among the styles common to this era are Greek Revival, Tidewater and Antebellum.
Victorian (1840 to 1900): With the technological innovation of mass production came the ability to produce large homes affordably. Queen Anne, Gothic Revival, Folk and Octagon are some of the architectural styles common to this era.
Gilded Age (1880 to 1929): The “Gilded Age” is a term popularized by Mark Twain to describe extravagant wealth. This era saw the construction of large, elaborate homes owned by a class of suddenly-rich businessmen who enjoyed grandiose displays of their new wealth.
Early 20^th Century homes: Homes built during this period were compact and economical, somewhat smaller and less pretentious than earlier Gilded Age homes.
Post-War homes (1945 to 1980): Very simple and affordable, some critics believe they have no style at all. Soldiers returning from the World War II spurred the construction of these homes, which emphasized utilitarianism over style more than preceding periods.
“Neo” houses (1965 to present): Theses houses borrow styles from previous architectural eras, such as Victorian, Colonial and Mediterranean. “McMansion” is a word used to describe large, quickly-constructed, flamboyant and poorly-designed neo-eclectic homes.

Other Ways to Determine a Building’s Age:

Check the meter reader. Sometimes, the meter reader will bear a date stamp.
Check the inside of the toilet. Toilet manufacturers often stamp the inside of tanks or lids with the year the toilet was made. Toilets are usually installed right after construction, so you can often determine a newer home’s age by inspecting a toilet.
In log homes, it may be possible to tell the building’s age by analyzing the tree rings in a piece of timber removed from the building. The science on which this is based, dendrochronology, does not arrive at an age based on the number of tree rings, but rather focuses on patterns of tree rings and compares these with known pattern ages for a specific region. This method is destructive and it requires a specialist.
Local town, county, or state tax records usually indicate the date or year a building was constructed.
Historical real estate listings may include indications of building age.
Census records can prove that a house was present at the time the census was taken.
Papers found inside the building will often indicate when the building was present. A house will probably be at least as old as, for instance, newspapers from the 1920s found in a crawlspace.
Employ an architectural investigator to date the house by studying its wood, plaster, mortar and paint.
The aluminum spacers within thermal-paned windows often bear the year of production, which can at least provide an approximate date of installation.
Sewer grates are sometimes stamped with the year they were manufactured, which may provide an age for the neighborhood.

In summary, there are many ways that inspectors and their clients may estimate the age of a building.

13 Aug

Aluminum Wiring

by Nick Gromicko, Rob London and Kenton Shepard

Between approximately 1965 and 1973, single-strand aluminum wiring was sometimes substituted for copper branch-circuit wiring in residential electrical systems Aluminum and copper wiring, with each metal clearly identifiable by its color

Aluminum and copper wiring, with each metal clearly identifiable by its color

due to the sudden escalating price of copper. After a decade of use by homeowners and electricians, inherent weaknesses were discovered in the metal that lead to its disuse as a branch wiring material. Although properly maintained aluminum wiring is acceptable, aluminum will generally become defective faster than copper due to certain qualities inherent in the metal. Neglected connections in outlets, switches and light fixtures containing aluminum wiring become increasingly dangerous over time. Poor connections cause wiring to overheat, creating a potential fire hazard. In addition, the presence of single-strand aluminum wiring may void a home’s insurance policies. Inspectors may instruct their clients to talk with their insurance agents about whether the presence of aluminum wiring in their home is a problem that requires changes to their policy language.

Facts and Figures

On April, 28, 1974, two people were killed in a house fire in Hampton Bays, New York. Fire officials determined that the fire was caused by a faulty aluminum wire connection at an outlet.
According to the Consumer Product Safety Commission (CPSC), “Homes wired with aluminum wire manufactured before 1972 [‘old technology’ aluminum wire] are 55 times more likely to have one or more connections reach “Fire Hazard Conditions” than is a home wired with copper.”

Aluminum as a Metal

Aluminum possesses certain qualities that, compared with copper, make it an undesirable material as an electrical conductor. These qualities all lead to loose connections, where fire hazards become likely. These qualities are as follows:

higher electrical resistance. Aluminum has a high resistance to electrical current flow, which means that, given the same amperage, aluminum conductors must be of a larger diameter than would be required by copper conductors.
less ductile. Aluminum will fatigue and break down more readily when subjected to bending and other forms of abuse than copper, which is more ductile. Fatigue will cause the wire to break down internally and will increasingly resist electrical current, leading to a buildup of excessive heat.
galvanic corrosion. In the presence of moisture, aluminum will undergo galvanic corrosion when it comes into contact with certain dissimilar metals.
oxidation. Exposure to oxygen in the air causes deterioration to the outer surface of the wire. This process is called oxidation. Aluminum wire is more easily oxidized than copper wire, and the compound formed by this process – aluminum oxide – is less conductive than copper oxide. As time passes, oxidation can deteriorate connections and present a fire hazard.
greater malleability. Aluminum is soft and malleable, meaning it is highly sensitive to compression. After a screw has been over-tightened on aluminum wiring, for instance, the wire will continue to deform or “flow” even after the tightening has ceased. This deformation will create a loose connection and increase electrical resistance in that location.
greater thermal expansion and contraction. Even more than copper, aluminum expands and contracts with changes in temperature. Over time, this process will cause connections between the wire and the device to degrade. For this reason, aluminum wires should never be inserted into the “stab,” “bayonet” or “push-in” type terminations found on the back of many light switches and outlets.
excessive vibration. Electrical current vibrates as it passes through wiring. This vibration is more extreme in aluminum than it is in copper, and, as time passes, it can cause connections to loosen.

Identifying Aluminum Wiring

Aluminum wires are the color of aluminum and are easily discernible from copper and other metals.
Since the early 1970s, wiring-device binding terminals for use with aluminum wire have been marked CO/ALR, which stands for “copper/aluminum revised.”
Look for the word “aluminum” or the initials “AL” on the plastic wire jacket. Where wiring is visible, such as in the attic or electrical panel, inspectors can look for printed or embossed letters on the plastic wire jacket. Aluminum wire may have the word “aluminum,” or a specific brand name, such as “Kaiser Aluminum,” marked on the wire jacket. Where labels are hard to read, a light can be shined along the length of the wire.
When was the house built? Homes built or expanded between 1965 and 1973 are more likely to have aluminum wiring than houses built before or after those years.

Options for Correction

Aluminum wiring should be evaluated by a qualified electrician who is experienced in evaluating and correcting aluminum wiring problems. Not all licensed electricians are properly trained to deal with defective aluminum wiring. The CPSC recommends the following two methods for correction for aluminum wiring:

Rewire the home with copper wire. While this is the most effective method, rewiring is expensive and impractical, in most cases.
Use copalum crimps. The crimp connector repair consists of attaching a piece of copper wire to the existing aluminum wire branch circuit with a specially designed metal sleeve and powered crimping tool. This special connector can be properly installed only with the matching AMP tool. An insulating sleeve is placed around the crimp connector to complete the repair. Although effective, they are expensive (typically around $50 per outlet, switch or light fixture).

Although not recommended by the CPSC as methods of permanent repair for defective aluminum wiring, the following methods may be considered:

application of anti-oxidant paste. This method can be used for wires that are multi-stranded or wires that are too large to be effectively crimped.
pigtailing. This method involves attaching a short piece of copper wire to the aluminum wire with a twist-on connector. the copper wire is connected to the switch, wall outlet or other termination device. This method is only effective if the connections between the aluminum wires and the copper pigtails are extremely reliable. Pigtailing with some types of connectors, even though Underwriters Laboratories might presently list them for the application, can lead to increasing the hazard. Also, beware that pigtailing will increase the number of connections, all of which must be maintained. Aluminum Wiring Repair (AWR), Inc., of Aurora, Colorado, advises that pigtailing can be useful as a temporary repair or in isolated applications, such as the installation of a ceiling fan.
CO/ALR connections. According to the CPSC, these devices cannot be used for all parts of the wiring system, such as ceiling-mounted light fixtures or permanently wired appliances and, as such, CO/ALR connections cannot constitute a complete repair. Also, according to AWR, these connections often loosen over time.
alumiconn. Although AWR believes this method may be an effective temporary fix, they are wary that it has little history, and that they are larger than copper crimps and are often incorrectly applied.
Replace certain failure-prone types of devices and connections with others that are more compatible with aluminum wire.
Remove the ignitable materials from the vicinity of the connections.

In summary, aluminum wiring can be a fire hazard due to inherent qualities of the metal. Inspectors should be capable of identifying this type of wiring.

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