Fed up waiting for the hot water?

Hot Water Recirculation Systems

A hot water recirculation system is a plumbing system that moves hot water to fixtures quickly without waiting for the water to get hot. Rather than relying on low water pressure, common in most water lines, recirculating systems rapidly move water from a water heater to the fixtures.

System Types 

• dedicated loop:  The circulation pump for this system is mounted on a pipe connected to the water heater tank down low. This is the cooler side of the loop, or the return.
  The hot water pipe is installed in a loop throughout the home, passing near each plumbing fixture. At each fixture, a short pipe connects the loop to the hot water valve. Because hot water is constantly circulating through the hot water loop, any time a valve is opened, it takes only a fraction of a second for hot water to reach the valve.

This helps extend the lifespan of the pump. If the home is not occupied, this pump will be probably be unplugged because the seller doesn't want to pay for its operation in an empty house. 

• integrated loop:  This system is typically used on retrofits but may also be installed on new construction. It consists of a pump installed under the plumbing fixture farthest from the water heater. The pump contains a sensor which switches the pump on when water temperature drops below 85° F, and switches it off when water temperature reaches 95° F. Newer pumps are adjustable from 77° to 104° F.
  
  In this system, hot water is re-circulated intermittently. Hot water is returned to the water heater via the cold water pipes. This raises the temperature of the cold water slightly, but it returns to the usual cold temperature in a short time.

Activation


Hot water recirculation systems are most commonly activated by either a thermostat or a timer. Systems that use a thermostat or timer automatically turn the pump on whenever the water temperature drops below a set point, or when the timer reaches a certain setting. These systems ensure that hot water is always available at the faucet.

Do they really save energy and water?


Regardless of whether they are controlled manually or automatically, recirculation systems reduce the amount of water that goes down the drain while the homeowner waits for the desired temperature. This fact allows for the following three advantages over conventional water distribution systems:

• They save time. Recirculating systems deliver hot water to faucets quickly, adding convenience for the homeowner.
• They conserve water. According to statistics from the U.S. Department of Energy and the U.S. Census Bureau, between 400 billion and 1.3 trillion gallons of water (or close to 2 million Olympic-sized swimming pools) are wasted nationally by households per year while waiting for water to heat up.
• They limit municipal energy waste. The DOE estimates that 800 to 1,600 kilowatt-hours per year are used to treat and pump the water to households that will eventually be wasted while the occupant waits for tap water to warm to the desired temperature.

If recirculation systems pump continuously, however, they have the potential to use significantly more energy. For a modest-sized pump, this might be 400 to 800 KWH a year if the pump runs all the time. Also, heat loss from the pipes can be significant if the hot water pipes are poorly insulated. This will result in the hot water heater running more. This added heat may be a benefit in the winter, but heat loss may add heat to the house in the summer and may result in higher bills for use of air conditioning.


Rebates


Some jurisdictions, particularly in areas where water is scarce, offer rebates on the purchase and installation of hot water recirculation systems. The cities of Santa Fe and Albuquerque, New Mexico, for instance, offer a $100 rebate for homeowners who purchase a hot water recirculation system. The city of Scottsdale, Arizona, offers up to $200 for residential property owners who install theses systems, although they must comply with UL-product and installation standards. Some systems may not comply with efficiency standards set by these municipalities.


Availability and Cost


Hot water recirculation systems are available nationwide from manufacturers, distributors, plumbing wholesale supply warehouses, and at selected retail home stores. The initial cost of dedicated systems may prevent some homeowners from installing these systems, as they require the purchase and installation of a pump and a large amount of piping. Integrated systems, by contrast, require only a pump and fittings. Energy savings will vary, depending on the design of the plumbing system, method of control and operation, and homeowner use. The system is easily installed and costs less than $400.

Take a look at your dryer

Dryer Vent Safety

Clothes dryers evaporate the water from wet clothing by blowing hot air past them while they tumble inside a spinning drum. Heat is provided by an electrical heating element or gas burner. Some heavy garment loads can contain more than a gallon of water which, during the drying process, will become airborne water vapor and leave the dryer and home through an exhaust duct (more commonly known as a dryer vent).

A vent that exhausts moist air to the home exterior has a number of requirements:

1. It should be connected. The connection is usually behind the dryer but may be beneath it. Look carefully to make sure it’s actually connected!
2. It should not be restricted. Dryer vents are often made from flexible plastic or metal duct, which may be easily kinked or crushed where they exit the dryer and enter the wall or floor. This is often a problem since dryers tend to be tucked away into small areas with little room to work. Vent hardware is available which is designed to turn 90° in a limited space without restricting the flow of exhaust air. Restrictions should be noted in the inspector's report. Airflow restrictions are a potential fire hazard!
3. One of the reasons that restrictions are a potential fire hazard is that, along with water vapor evaporated out of wet clothes, the exhaust stream carries lint – highly flammable particles of clothing made of cotton and polyester. Lint can accumulate in an exhaust duct, reducing the dryer’s ability to expel heated water vapor, which then accumulates as heat energy within the machine. As the dryer overheats, mechanical failures can trigger sparks, which can cause lint trapped in the dryer vent to burst into flames. This condition can cause the whole house to burst into flames! Fires generally originate within the dryer but spread by escaping through the ventilation duct, incinerating trapped lint, and following its path into the building wall.

InterNACHI believes that house fires caused by dryers are far more common than are generally believed, a fact that can be appreciated upon reviewing statistics from the National Fire Protection Agency. Fires caused by dryers in 2005 were responsible for approximately 13,775 house fires, 418 injuries, 15 deaths, and $196 million in property damage. Most of these incidents occur in residences and are the result of improper lint cleanup and maintenance. Fortunately, these fires are very easy to prevent.

The recommendations outlined below reflect International Residential Code (IRC) SECTION M1502 CLOTHES DRYER EXHAUST guidelines:

M1502.5 Duct construction.
Exhaust ducts shall be constructed of minimum 0.016-inch-thick (0.4 mm) rigid metal ducts, having smooth interior surfaces, with joints running in the direction of air flow. Exhaust ducts shall not be connected with sheet-metal screws or fastening means which extend into the duct.

This means that the flexible, ribbed vents used in the past should no longer be used. 

M1502.6 Duct length.

The maximum length of a clothes dryer exhaust duct shall not exceed 25 feet (7,620 mm) from the dryer location to the wall or roof termination. The maximum length of the duct shall be reduced 2.5 feet (762 mm) for each 45-degree (0.8 rad) bend, and 5 feet (1,524 mm) for each 90-degree (1.6 rad) bend. The maximum length of the exhaust duct does not include the transition duct.

This means that vents should also be as straight as possible and cannot be longer than 25 feet. Any 90-degree turns in the vent reduce this 25-foot number by 5 feet, since these turns restrict airflow.

A couple of exceptions exist:

1. The IRC will defer to the manufacturer’s instruction, so if the manufacturer’s recommendation permits a longer exhaust vent, that’s acceptable. An inspector probably won’t have the manufacturer’s recommendations, and even if they do, confirming compliance with them exceeds the scope of a General Home Inspection.
2. The IRC will allow large radius bends to be installed to reduce restrictions at turns, but confirming compliance requires performing engineering calculation in accordance with the ASHRAE Fundamentals Handbook, which definitely lies beyond the scope of a General Home Inspection!

M1502.2 Duct termination.
Exhaust ducts shall terminate on the outside of the building or shall be in accordance with the dryer manufacturer’s installation instructions. Exhaust ducts shall terminate not less than 3 feet (914 mm) in any direction from openings into buildings. Exhaust duct terminations shall be equipped with a backdraft damper. Screens shall not be installed at the duct termination.

Inspectors will see many dryer vents terminate in crawlspaces or attics where they deposit moisture, which can encourage the growth of mold, wood decay, or other material problems. Sometimes they will terminate just beneath attic ventilators. This is a defective installation. They must terminate at the exterior and away from a door or window! Also, screens may be present at the duct termination and can accumulate lint and should be noted as improper. 

M1502.3 Duct size.
The diameter of the exhaust duct shall be as required by the clothes dryer’s listing and the manufacturer’s installation instructions.

Look for the exhaust duct size on the data plate.

M1502.4 Transition ducts.
Transition ducts shall not be concealed within construction. Flexible transition ducts used to connect the dryer to the exhaust duct system shall be limited to single lengths not to exceed 8 feet (2438 mm), and shall be listed and labeled in accordance with UL 2158A.

How long will that water heater last?

Estimating the Lifespan of a Water Heater

While the typical water heater has a lifespan of about 10 years, careful consideration of the factors that pertain to its lifespan can provide the homeowner with information about the potential costs that would be incurred by replacing the water heater. These factors include: correct installation; usage volume; construction quality; and maintenance.

Correct Installation

A water heater should generally be installed upright. Installing a water heater on its side will place  structural stress on it due to inadequate support for the heater and its pipes, and may cause premature failure.

Water heaters should be installed in well-ventilated areas -- not just for fire safety requirements and nitrous-oxide buildup, but also because poor ventilation can shorten the lifespan of the water heater.

A water heater should not be placed in an area susceptible to flood damage. Water can rust out the exterior and pipes, decreasing the life expectancy and efficiency of the unit.  A water heater is best placed in an easily accessible area for maintenance.  It should also be readily visible for fire and health-hazard requirements.

The inspector may wish to inquire as to whether the water heater was installed professionally. Homeowners may install their own units to save money, but the installation of a tankless gas water heater, for example, requires more skill than the average DIY task.  In the case of the owner-installed tankless gas water heater, the home inspector may want to check the gas pipe work for leaks to determine whether there is adequate ventilation.

Usage

The life expectancy of the water heater depends a great deal on the volume of water used. Using large quantities of water means that the water heater will have to work harder to heat the water. In addition, the greater the volume of water, the greater the corrosive effect of the water will be.

Construction Quality of the Water Heater

As with most household systems and components, you get what you pay for in a water heater. Cheaper models will generally have a shorter lifespan, while more expensive models will generally last longer. A good indication of a water heater’s construction quality is its warranty.  Longer warranties naturally imply sounder construction. According to a 2007 Consumer Report that deconstructed 18 different models of water heaters, it was determined that models with longer warranties invariably were of superior manufacturing quality, with nine- and 12-year models typically having larger or higher-wattage heating elements, as well as thicker insulation. Models with larger heating elements have a much better resistance to mineral buildup or scum. 

Pay attention to the model's features.  Porcelain casing, for example, provides an additional layer of protection against rusting, and a greater level of heat insulation. Some models come with a self-cleaning feature that flushes the pipes of mineral deposits, which is an important consideration in the unit's lifespan.  Models with larger or thicker anodes are better-equipped to fight corrosion.

Maintenance and Parts Replacement

The hardness of the water is another consideration when looking at estimating the lifespan of a water heater.  In areas where there is a higher mineral content to the water, water heaters have shorter lifespans than in other areas, as mineral buildup reduces the units' efficiency. Even in areas where the water is softer, however, some mineral deposition is bound to occur.  A way to counteract this mineral buildup is to periodically flush the water heater system, which not only removes some of the buildup, but, in tank systems, the process heats the water in the tank. Higher-end models typically come equipped with a self-flushing feature.  In models for which manual flushing is required, it is important not to damage the water heater valve, which is usually made of plastic and is easy to break.

Although an older model may appear to be well-maintained, a question arises:  Is the maintenance worth it? Warranties often exclude labor costs, so a good rule to follow is that if the total repair cost per year is greater than 10% of the cost of buying and installing a new water heater, it is probably not worth replacing damaged parts. 

It is debatable whether the cost in time and money of replacing the sacrificial anode in a water heater is worth the benefit of prolonging the use of the existing water heater by a couple of years. In the tricky process of emptying the tank and replacing the anode, it is easy to damage the unit, and, as some warranties can be voided by anode replacement, the cost of future repairs or maintenance that might otherwise be covered must be considered. 

In summary, there is a variety of factors influencing the lifespan of a water heater. Beyond the basic telltale signs, such as a leaky puddle under the heater or cold showers in the morning that indicate that a new water heater is probably in order, the homeowner should consider the age and warranty of the model, and carefully weigh the cost-benefit of maintaining an existing heater versus buying a new one.

It's Not Easy to Picture Water as Being Hard

Hard Water

Water "hardness" refers to the level of minerals found in a home’s water supply.  Hard water results when an excessive amount of minerals, chiefly calcium and magnesium, are dissolved into water as it passes through soil and rock. The degree of hardness becomes greater as the mineral content increases. Hard water presents numerous mechanical and aesthetic problems in homes, but it is not considered a health hazard to humans.

Identifying Hard Water

The best way to determine whether or not a home has hard water is to have it tested. For homes served by municipal water systems, you can ask the water supplier about the hardness level of the water they deliver. Private water supplies can be tested for hardness. However, hard water (especially if it is excessively hard) can be detected by inspectors and their clients through the negative effects it has on a home. The most common problems associated with hard water are:

• poor washing machine performance. Clothes washed in hard water often look dingy and feel scratchy or stiff. Continuous laundering in hard water can damage fibers and shorten the lifespan of clothes;
• a mineral ring around the tip of a faucet or in a toilet bowl;
• unsightly, whitish scale deposits in pipes, water heaters, tea kettles, pots, silverware and dishes;
• calcification of taps and shower- heads;
• inefficient and costly operation of water-using appliances. Pipes can become clogged with scale that reduces water flow, ultimately requiring pipe replacement. Crystalline deposits (limescale) have been known to increase energy bills considerably;
• soap curd and scum in washbasins and bathtubs. Bathing with soap in hard water leaves a film of sticky soap curd on the skin, which may prevent removal of soil and bacteria. Soap curd on hair may make it dull, lifeless and difficult to manage. Soap curd also interferes with the return of skin to its normal, slightly acid condition, and may lead to irritation; and
• limescale in solar heating systems. Solar heating, often used to heat swimming pools, is prone to limescale buildup, which can reduce the efficiency of the electronic pump.

Hard Water Concentration Levels

Descriptions of water hardness correspond with ranges of mineral concentrations, as measured below in parts per million (ppm):

Description of Water Hardness Level

Harness Level	Concentration of harness minerals in grains per gallon (gpg)	Milligrams per liter (mg/l) or parts per million (ppm)
Soft	less than 1	less than 17
Slightly Soft	1 - 3.5	17 - 60
Moderately Hard	3.5 - 7	61 - 120
Hard	7 - 10.5	121 - 180
Very Hard	more than 10.5	more than 180

Note that since water's acidity and temperature partly determines the behavior of hard water, a single-number scale does not adequately describe the realistic effects of hard water on household components.

Hard Water and Human Health

The World Health Organization reports, " There does not appear to be any convincing evidence that water hardness causes adverse health effects in humans. In contrast, the results of a number of epidemiological studies have suggested that water hardness may protect against disease." The report further states that hard water often contributes a small amount toward total calcium and magnesium human dietary needs.

Geographic Distribution of Hard Water in the U.S.

According to the U.S. Geological Survey, softest waters are in the Pacific Northwest, parts of New England, the South Atlantic-Gulf states, and Hawaii. Moderately hard waters are common in many rivers of Alaska and Tennessee, in the Great Lakes region, and the Pacific Northwest. Hardest waters (greater than 1,000 mg/L) are measured in streams in Texas, New Mexico, Kansas, Arizona and Southern California.

Treatment:  Softeners and Conditioners

Water softeners remove unwanted minerals through an ion-exchange process. Incoming hard water passes through a tank of ion- exchange beads that are super-saturated with sodium. The calcium and magnesium ions in the water attach to the resin beads, replacing the sodium, which is then released into the water. The softened water is subsequently distributed for use throughout the house, but it may be unsuitable for drinking due to its high sodium content.

In water conditioners, by contrast, calcium ions remain suspended in the water as small particles, but their tendency to form limescale is diminished. This system allows the benefit that the calcium, which is a good dietary mineral, remains in the water. Water conditioners are more controversial and they do not work in every situation.

In summary, the common problem of hard water is easy to spot and mitigate.

Electromagnetic Fields in the Home

Electromagnetic Fields

Can the electric and magnetic fields (EMFs) to which people are routinely exposed cause health effects? What are sources of EMFs, and when are they dangerous?

An "electromagnetic field" is a broad term which includes electric fields generated by charged particles in motion, and radiated fields, such as TVs, radios, hair dryers and microwave ovens. Electric fields are measured in units of volts per meter, or V/m. Magnetic fields are measured in milli-Gauss, or mG. The field is always strongest near the source and diminishes as you move away from the source. These energies have the ability to influence particles at great distances. For example, the radiation from a radio tower influences the atoms within a distant radio antenna, allowing it to pick up the signal. Despite the many wonderful conveniences of electrical technology, the effects of EMFs on biological tissue remains the most controversial aspect of the EMF issue, with virtually all scientists agreeing that more research is necessary to determine safe or dangerous levels.

Research since the mid-1970s has provided extensive information on biological responses to power-frequency electric and magnetic fields. The Electric and Magnetic Fields (EMF) Research and Public Information Dissemination (RAPID) Program was charged with the goal of determining if electric and magnetic fields associated with the generation, transmission and use of electrical energy pose a risk to human health. The fact that 20 years of research have not answered that question is clear evidence that health effects of EMF are not obvious and that risk relationships, if risk is identified, are not simple. Because epidemiologic studies have raised concerns regarding the connection between certain serious human health effects and exposure to electric and magnetic fields, the program adopts the hypothesis that exposure to electric or magnetic fields under some conditions may lead to unacceptable risk to human health. The focus of the program is not only to test (as far as possible within the statutory time limits) that hypothesis for those serious health effects already identified, but to identify, as far as possible, the special conditions that lead to elevated risk, and to recommend measures to manage risk. 

Electromagnetic hypersensitivity (ES) is a physiological disorder characterized by symptoms directly brought on by exposure to electromagnetic fields. It produces neurological and allergic-type symptoms. Symptoms may include, but are not limited to, headache, eye irritation, dizziness, nausea, skin rash, facial swelling, weakness, fatigue, pain in joints and/or muscles, buzzing/ringing in the ears, skin numbness, abdominal pressure and pain, breathing difficulty, and irregular heartbeat. Those affected persons may experience an abrupt onset of symptoms following exposure to a new EMF, such as fields associated with a new computer or with new fluorescent lights, or a new home or work environment. Onset of ES has also been reported following chemical exposure. 


A concerted effort to provide scientifically valid research on which to base decisions about EMF exposures is underway, and results are expected in the next several years. Meanwhile, some authorities recommend taking simple precautionary steps, such as the following:

• Increase the distance between yourself and the EMF source – sit at arm’s length from your computer terminal.
• Avoid unnecessary proximity to high EMF sources – don’t let children play directly under power lines or on top of power transformers for underground lines.
• Reduce time spent in the field – turn off your computer monitor and other electrical appliances when you aren’t using them.

The Office of Technology Assessment of the Congress of the United States recommends a policy of “prudent avoidance” with respect to EMF.  "Prudent avoidance" means to measure fields, determine the sources, and act to reduce exposure.

1. Detect EMFs in your home and work environment. It is good to know where the sources of EMFs are in your everyday world and how strong these sources are. Is there wiring in the wall behind your bed that you don’t even know about? Is the vaporizer emitting strong fields in the baby’s room? How much EMFs are you and your family getting from the power lines in the street? Even hair dryers emit EMFs. Home inspectors often have meters to measure EMFs, or they can be purchased and shared with friends.
   
2. Diminish your exposure to the EMFs you find. Determine how far you must stay away from the EMF emitters in your home and work environment to achieve less than 2.5 mG of exposure — the microwave oven, the alarm clock, the computer, and so on. Rearrange your furniture (especially the beds, desks, and couches where you spend the most time) away from heaters, wiring, fluorescent lights, electric doorbells, and other EMF “hot spots.” Where practical, replace electrical appliances with non-electric devices. Have an electrician correct faulty high EMF wiring and help you eliminate dangerous stray ground currents. Consult a qualified EMF engineer, if necessary. Contact the National Electromagnetic Field Testing Association at 1-847-475-3696 for consultants in your area.
   
3. Shield yourself. Use shielding devices on your computer screen and cellular phone. Add shielding to your household wiring, circuit box and transformers.

Magnetic fields are not blocked by most materials. Magnetic fields encountered in homes vary greatly. Magnetic fields rapidly become weaker with distance from the source.

• Electric fields in the home, on average, range from 0 to 10 volts per meter. They can be hundreds, thousands, or even millions of times weaker than those encountered outdoors near power lines. 
• Electric fields directly beneath power lines may vary from a few volts per meter for some overhead distribution lines to several thousands of volts per meter for extra-high voltage power lines. 
• Electric fields from power lines rapidly become weaker with distance and can be greatly reduced by walls and roofs of buildings.

Home Based Electrical Generators

I am inspecting more and more homes that use a generator to supply electricity to their home in the case of a power outage, either out of necessity or convenience. As a home buyer you may want to know about generators and the potential hazards they present when improperly wired or utilized.


Generator Types


There are two main types of generators: permanently installed, standby generators; and gasoline-powered, portable generators.


Standby Generators


Standby generators typically operate on natural gas or liquid propane. They remain fixed in place outside the home and are designed to supply on-site power to specified circuits through a home's electrical wiring. These generators work in tandem with a manual or automatic transfer switch, which automatically detects an interruption in grid-powered electricity and subsequently transfers over electrical input to the generator. The transfer switch suspends input from the generator once it senses that utility-powered electricity has resumed. Generators for small- to medium-size homes are typically air-cooled and employ fans to regulate the temperature inside the unit. Liquid-cooled units are used for the larger energy loads in larger homes.


Some advantages of standby generators are as follows:

• They may be turned on manually, or they may be programmed to switch on automatically in the case of a power outage even when no one is home.
• Power may be supplied for extended periods of time.
• Hard-wired systems, such as a home's furnace, well pump and air conditioner, may maintain continuous power.
• Uninterrupted power can be supplied to systems that must remain on continuously, such as medical equipment used for breathing, etc.

Disadvantages of standby generators are as follows:

• Installation may require a permit.
• A qualified technician, such as an electrician, is required to install the ATS and to determine the electrical load requirements for the circuits in a home.
• Routine maintenance is required.
• Standby generators may be prohibitively expensive. 

Portable Generators


Gasoline-powered, portable generators are typically smaller in size and power capacity than permanently installed generators. They are designed so that corded electrical devices may be plugged directly into them.


Advantages to portable generators are as follows:

• Portable generators are versatile. They may be used at home or transported and utilized in remote locations, such as a campground or a construction site.
• They do not require complicated installation.
• They typically do not require permits.
• Portable units are generally less expensive than standby generators.

Disadvantages of portable generators:

• Devices that are hard-wired into a home's electrical system cannot be powered by a portable generator if no transfer switch is installed.

Hazards

• Portable and standby generators produce dangerous carbon monoxide (CO) gas, which can be deadly if inhaled.
• Inexperienced installers are exposed to the risk of electrical shock. Only qualified electricians should attempt to install a generator.
• Overloading a generator may result in reduced fuel efficiency, damage to appliances or fire.
• Standby generators or their required transfer switches that are incorrectly wired (or missing) may result in "back-feed" -- a hazardous condition in which an electrical current is fed back into the grid -- which could potentially electrocute and kill homeowners, utility workers, and others who are using the same utility transformer.
• Connecting a portable generator directly into a home's wall outlet can also cause dangerous back-feed.
• Generators that are exposed to water or that are not properly grounded can cause electrocution.
• Gasoline for portable generators is highly flammable and may cause a fire when exposed to an open flame or when spilled on the hot generator.
• Over-taxed cords attached to a portable generator may cause a fire.

Inspection


As an inspector I check for the following:

1. Generators should never be used anywhere indoors, even if the area is ventilated.
2. Portable generators placed outside should not be near doors, vents or open windows leading into the home.
3. Carbon-monoxide detectors should be installed in case CO is accidentally released into the home.
4. Portable generators should not be plugged directly into a home's electrical receptacles.
5. A standby generator hard-wired into a home should have a transfer switch installed to prevent backfeeding. This device situated between the generator and the main electrical panel.
6. Generators should be properly grounded.
7. Units should be dry and shielded from contact with liquid.
8. Only heavy-duty electrical cords that are rated for outdoor use should be plugged into portable generators.
9. Electrical cords should not have any punctures or exposed wiring.
10. Cords running from portable generators should be kept out of the way of foot traffic and should not run underneath rugs.
11. The total electrical capacity of the generator should exceed the power requirements of the devices that the unit is supplying.
12. Fuel for portable generators should be stored away from the home and children in clearly labeled and durable containers.

In summary, generators can be lifesavers during a power outage, but they present serious health and safety concerns if they are not installed and used properly. Get it inspected If you come across one in a house you are considering.

Ground-Fault Circuit Interrupters (GFCIs)

What is a GFCI?

A ground-fault circuit interrupter, or GFCI, is a device used in electrical wiring to disconnect a circuit when unbalanced current is detected between an energized conductor and a neutral return conductor.  Such an imbalance is sometimes caused by current "leaking" through a person who is simultaneously in contact with a ground and an energized part of the circuit, which could result in lethal shock.  GFCIs are designed to provide protection in such a situation, unlike standard circuit breakers, which guard against overloads, short circuits and ground faults. 

It is estimated that about 300 deaths by electrocution occur every year, so the use of GFCIs has been adopted in new construction, and recommended as an upgrade in older construction, in order to mitigate the possibility of injury or fatality from electric shock.

History

The first high-sensitivity system for detecting current leaking to ground was developed by Henri Rubin in 1955 for use in South African mines.  This cold-cathode system had a tripping sensitivity of 250 mA (milliamperes), and was soon followed by an upgraded design that allowed for adjustable trip-sensitivity from 12.5 to 17.5 mA.  The extremely rapid tripping after earth leakage-detection caused the circuit to de-energize before electric shock could drive a person's heart into ventricular fibrillation, which is usually the specific cause of death attributed to electric shock.

Charles Dalziel first developed a transistorized version of the ground-fault circuit interrupter in 1961.  Through the 1970s, most GFCIs were of the circuit-breaker type.  This version of the GFCI was prone to frequent false trips due to poor alternating-current characteristics of 120-volt insulations.  Especially in circuits with long cable runs, current leaking along the conductors’ insulation could be high enough that breakers tended to trip at the slightest imbalance. 

Since the early 1980s, ground-fault circuit interrupters have been built into outlet receptacles, and advances in design in both receptacle and breaker types have improved reliability while reducing instances of "false trips," known as nuisance-tripping.

Testing Receptacle-Type GFCIs

Receptacle-type GFCIs are currently designed to allow for safe and easy testing that can be performed without any professional or technical knowledge of electricity.  GFCIs should be tested right after installation to make sure they are working properly and protecting the circuit.  They should also be tested once a month to make sure they are working properly and are providing protection from fatal shock. 

To test the receptacle GFCI, first plug a nightlight or lamp into the outlet. The light should be on.  Then press the "TEST" button on the GFCI. The "RESET" button should pop out, and the light should turn off.

If the "RESET" button pops out but the light does not turn off, the GFCI has been improperly wired. Contact an electrician to correct the wiring errors.

If the "RESET" button does not pop out, the GFCI is defective and should be replaced.

If the GFCI is functioning properly and the lamp turns off, press the "RESET" button to restore power to the outlet.