Harmonic Distortion

An electricity meter measures electrical energy consumption in homes, businesses, and industries. Also called a power meter or energy meter, it records kilowatt-hours, supports billing, monitors usage patterns, and ensures accurate tracking of electrical load.

What is an Electricity Meter?

An electricity meter is a vital device that utility companies use to measure the amount of electric power consumed by a household or business.

✅ Tracks consumption in kilowatt-hours (kWh) for accurate billing

✅ Monitors load, efficiency, and usage trends over time

✅ Essential for power distribution, energy management, and safety

It provides valuable data that helps both consumers and utility companies monitor power consumption, leading to improved energy management and more accurate billing.

How does an electricity meter work?

It measures the amount of power a household or business consumes, typically in kilowatt-hours (kWh). It records usage over time, allowing utility companies to bill customers accordingly.

Various types exist to suit different applications. The most common include:

• Electromechanical meters (kWh) with a rotating aluminum disc that measures energy flow.

• Digital meters that display consumption on an electronic screen.

• Smart meters are advanced digital devices that automatically transmit usage data to the utility.

Smart meters are central to the smart grid, a modernized system designed to improve the efficiency and reliability of power distribution. With a smart device, consumers can access real-time information about their usage while utilities can implement time-of-use billing to encourage energy conservation during peak hours.

Net Metering & Solar Export Meters

For households with solar panels or other distributed energy sources, net recorders facilitate two-way power flow. They measure both the electrical energy consumed from the grid and the power exported back to it. This enables net metering programs, allowing consumers to earn credits or payments for surplus energy, making the adoption of renewable energy more cost-effective.

Communication & Technology Behind Smart Meters

Smart meters are part of the Advanced Metering Infrastructure (AMI), which utilizes communication networks, including RF mesh, cellular, and power line communication (PLC), to securely transmit usage data to the utility. This connectivity enables demand response programs, remote disconnections, and predictive maintenance, while providing consumers with detailed insights via apps and dashboards.

How do I read my Electricity Meter?

Reading your device may seem complicated, but it’s straightforward:

• Electromechanical types use dials. Read each from left to right, taking the lower number if the pointer is between two digits.

• Digital types display readings directly on an LCD screen, often cycling through consumption, demand, and tariff data.
  Some utilities also offer web portals or mobile apps that allow consumers to track their daily or hourly usage.

How can I check if my Electricity Meter is accurate?

To test accuracy, turn off all appliances and observe whether the recorder continues to record consumption. If it does, contact your utility for a professional inspection. Most utilities are required by regulation to maintain meter accuracy within specific tolerances defined by ANSI or IEC standards.

One innovation is the prepaid electricity meter, where consumers pay in advance for power. Once the credit is exhausted, the supply is disconnected until it is recharged. This approach enables households to budget more effectively and promotes conscious energy use.

Security & Privacy in Modern Meters

Electricity meter tampering is a significant concern for utilities. Attempts to reduce recorded consumption can lead to safety hazards and financial losses. Modern recorders include anti-tamper seals, encrypted communication, and intrusion detection to protect data integrity and ensure accurate billing. Utilities also conduct regular inspections to detect and prevent fraud.

What is a Smart Electricity Meter, and how does it differ?

It is a digital device that provides real-time usage data, supports two-way communication, and integrates with the smart grid. Unlike traditional recorders, it enables:

• Automated reading

• Dynamic tariffs and demand response

• Access to consumer dashboards, apps, and alerts

These capabilities enhance billing accuracy, empower consumers to lower their energy costs, and facilitate a more flexible and sustainable grid.

Market Adoption & Trends

Smart meter adoption is growing worldwide. According to industry reports, over 1 billion smart meters have been deployed globally, with continued growth expected in North America, Europe, and Asia. In Canada, utilities like BC Hydro have rolled out smart meters to millions of customers, aiming for more reliable service and reduced outages.

Pros, Cons, and Challenges

Electricity meters offer several clear benefits, including accurate billing, improved energy management, integration with renewable energy sources, and reduced costs associated with manual meter reading. However, challenges include upfront costs, connectivity issues, consumer privacy concerns, and potential inaccuracies if meters drift out of calibration. Addressing these ensures the technology continues to deliver long-term benefits.

The Role of Electricity Meters in Energy Management

Understanding how they work, how to read them, and the different types available helps consumers make informed decisions about their energy usage. By verifying accuracy, adopting advanced technologies such as smart and prepaid meters, and utilizing apps and dashboards, households and businesses can gain greater control over their energy costs.

Ultimately, electricity meters are not just billing devices—they are gateways to improved efficiency, consumer empowerment, and a sustainable energy future.

Frequently Asked Questions

Can I read my smart meter remotely?

Yes. Most enable consumers to view their data via apps or online dashboards provided by their utilities.

How accurate are they?

They must comply with standards like ANSI C12 or IEC 62053, ensuring accuracy within strict tolerances.

What happens if it fails?

If it malfunctions, utilities are legally required to replace it and may use historical usage patterns for interim billing.

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Dynamic electricity is the continuous flow of electric charge—electric current—through a conductor, typically driven by a voltage source. Think of it like water flowing in a pipe, where electrons move uniformly to carry energy.

Voltage drop occurs when electrical voltage decreases as current flows through a conductor. It can cause poor equipment performance, energy loss, and overheating. Discover how selecting the proper wire size and material can help minimize voltage drop in electrical systems.

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What is Voltage Drop?

Voltage drop (VD) is a common issue in electrical systems where the voltage (V) at the end of a circuit is lower than at the beginning due to resistance in the wiring.

✅ A decrease in V along a wire or circuit due to resistance or impedance

✅ Leads to reduced equipment performance and higher energy consumption

✅ Prevented by proper wire sizing, shorter runs, and low-resistance materials

Voltage Drop Definition

Voltage drop can lead to inefficient equipment operation or even failure. Solving electrical potential drop involves ensuring proper wire sizing, minimizing long-distance wiring runs, and using materials with lower resistance. Calculating the voltage drop for specific circuits and adjusting the installation accordingly helps maintain optimal performance and prevent power loss.

Any length or size of wires will have some resistance, and running a current through this dc resistance will cause the voltage to drop. As the length of the cable increases, so does its resistance and reactance increase in proportion. Hence, circuit V drop is particularly a problem with long cable runs, for example, in larger buildings or on larger properties such as farms. This technique is often used when properly sizing conductors in any single-phase, line-to-line electrical circuit. This can be measured with a voltage drop calculator.

Electrical cables have a carrying capacity of current that always presents inherent resistance, or impedance, to the flow of current. Voltage drop is measured as the amount of loss which occurs through all or part of a circuit due to what is called cable "impedance" in volts.

Too much resistance in wires, otherwise known as " excessive voltage drop ", in a cable's cross-sectional area can cause lights to flicker or burn dimly, heaters to heat poorly, and motors to run hotter than normal and burn out. This condition causes the load to work harder with less energy, pushing the current.

Voltage Drop per 100 Feet of Copper Wire (Single Phase, 60 Hz, 75°C, 120V Circuit)

(Values are approximate, in volts, for a 2% limit)

Key Takeaways

• Larger wires (lower AWG numbers) carry more current with less VD.

• Longer distances require thicker wires to stay within VD limits.

• A 2% VD is often used as a conservative design target in electrical systems.

How is this solved?

To decrease the voltage drop in a circuit, you need to increase the size (cross-section) of your conductors – this is done to lower the overall resistance of the cable length. Certainly, larger copper or aluminum cable sizes increase the cost, so it’s essential to calculate the voltage drop and determine the optimum wire size that will reduce voltage drop to safe levels while remaining cost-effective.

How do you calculate voltage drop?

Voltage drop refers to the loss of electricity that occurs when current flows through a resistance. The greater the resistance, the greater the voltage drop. To check the voltage drop, use a voltmeter connected between the points where the voltage drop is to be measured. In DC circuits and AC resistive circuits, the total of all the voltage drops across series-connected loads should add up to the V applied to the circuit (Figure 1).

Fig. 1. Measuring voltage drops across loads

Read our companion article Voltage Drop Calculator. For more information, see our article: Voltage Drop Formula.

Each load device must receive its rated power to operate properly. If not enough is available, the device will not operate as it should. You should always be certain that the V you are going to measure does not exceed the range of the voltmeter. This may be difficult if the V is unknown. If such is the case, you should always start with the highest range. Attempting to measure a V higher than the voltmeter can handle may cause damage to the voltmeter. At times you may be required to measure a V from a specific point in the circuit to ground or a common reference point (Figure 8-15). To do this, first connect the black common test probe of the voltmeter to the circuit ground or common. Then connect the red test probe to whatever point in the circuit you want to measure.

To accurately calculate the drop for a given cable size, length, and current, you need to accurately know the resistance of the type of cable you’re using. However, AS3000 outlines a simplified method that can be used.

The table below is taken from AS3000 electrical code, which specifies ‘Amps per %Vd‘ (amps per percentage VD) for each cable size.  To calculate the dop for a circuit as a percentage, multiply the current (amps) by the cable length (metres); then divide this Ohm number by the value in the table.

For example, a 30m run of 6 mm² cable carrying 3-phase 32A will result in a 1.5% drop: 32A × 30m = 960A / 615 = 1.5%.

Learn more about real-world voltage drop issues on our Voltage Dropping in Power Quality page.

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Electricity terms explain voltage, current, resistance, impedance, power factor, frequency, AC/DC, circuits, transformers, and load. Master key definitions to analyze systems, size conductors, mitigate harmonics, and ensure safety compliance.

What Are Electricity Terms?

Standardized definitions for voltage, current, resistance, impedance, and power factor used in electrical engineering.

✅ Define units, symbols, and formulas per IEEE/IEC standards

✅ Clarify AC/DC behavior, phasors, impedance, and power factor

✅ Aid circuit analysis, sizing conductors, and safety compliance

Here are the top 50 commonly used electricity terms that are essential for understanding electrical systems, devices, and concepts: For a broader glossary with context and examples, see the curated list at Electrical Terms by Electricity Forum for deeper reference.

Voltage (V) – The electrical potential difference between two points in a circuit. Understanding how potential difference relates to the nature of electricity is clarified in this overview of what electricity is and how it behaves.

Current (I) – The flow of electric charge, measured in amperes (A). A concise explanation of electricity as a physical phenomenon is given in this definition of electricity for foundational understanding.

Resistance (R) – Opposition to current flow, measured in ohms (Ω).

Power (P) – The rate of doing work or transferring energy, measured in watts (W).

Ohm's Law – The relationship between voltage, current, and resistance. For a step-by-step refresher on the relationships among voltage, current, and resistance, explore this basic electricity guide to connect theory with practical examples.

Alternating Current (AC) – Electric current that reverses direction periodically.

Direct Current (DC) – Electric current that flows in one direction only. For a side-by-side comparison of waveform behavior, applications, and conversion methods, review the differences between AC and DC to strengthen conceptual understanding.

Frequency (f) – The number of cycles per second in AC, measured in hertz (Hz).

Impedance (Z) – The total opposition to current flow in an AC circuit, combining resistance and reactance, measured in ohms.

Capacitance (C) – The ability to store electrical energy in an electric field, measured in farads (F).

Inductance (L) – The ability of a conductor to induce a voltage when current changes, measured in henries (H).

Power Factor (PF) – The ratio of real power to apparent power, indicating the efficiency of a system.

Real Power (P) – The actual power consumed to perform work, measured in watts.

Apparent Power (S) – The total power in a system, combining real and reactive power, measured in volt-amperes (VA).

Reactive Power (Q) – Power in AC circuits that does not perform useful work, measured in volt-amperes reactive (VAR).

Load – The device or equipment that consumes electrical power.

Short Circuit – An abnormal connection between two points in a circuit, causing excessive current flow. To ground this topic in fundamentals, revisit what an electrical circuit is before examining fault conditions.

Overload – A condition where a circuit or device exceeds its rated current capacity.

Circuit Breaker – A protective device that interrupts the flow of current when an overload or short circuit occurs.

Fuse – A protective device that melts to break the circuit when excessive current flows.

Grounding (Earthing) – Connecting parts of an electrical system to the Earth to ensure safety.

Transformer – A device that transfers electrical energy between two or more circuits through electromagnetic induction.

Conductor – A material that allows the flow of electrical current, typically copper or aluminum.

Insulator – A material that resists the flow of electric current, such as rubber or plastic.

Phase – The distribution of alternating current electricity into separate waveforms, often used in three-phase power systems.

Watt (W) – The unit of power, equivalent to one joule per second.

Kilowatt (kW) – A unit of power equal to 1,000 watts.

Megawatt (MW) – A unit of power equal to 1 million watts.

Voltage Drop – The reduction in voltage across a component or conductor in an electrical circuit.

Arc Flash – A dangerous condition associated with the release of energy caused by an electric arc.

Resistor – A component that opposes the flow of current, used to control voltage and current in circuits.

Diode – A semiconductor device that allows current to flow in one direction only.

Rectifier – A device that converts AC to DC.

Inverter – A device that converts DC to AC.

Contactor – An electrically controlled switch used to control a power circuit.

Relay – A switch operated by an electromagnet, used for controlling circuits.

Switchgear – Equipment used to switch, control, and protect electrical circuits.

Distribution System – The system of wires and equipment that delivers electricity from substations to consumers.

Neutral – A conductor that carries current back to the source in an electrical system.

Busbar – A conductor used to distribute power from one source to multiple circuits.

Overcurrent Protection – Devices like fuses and circuit breakers designed to protect circuits from excessive current.

Phase Angle – The angular displacement between voltage and current waveforms in AC circuits.

Power Supply – A device that provides the necessary electrical power to a circuit or device.

Generator – A device that converts mechanical energy into electrical energy. This ties directly to how electrical energy is produced, transferred, and ultimately consumed.

Motor – A device that converts electrical energy into mechanical energy.

Frequency Converter – A device that changes the frequency of AC power.

Power Grid – A network of transmission lines, substations, and power stations for distributing electricity.

Service Panel – The central distribution point for electrical circuits in a building, containing circuit breakers or fuses.

Utility Transformer – A transformer that steps down high voltage for distribution to consumers.

Harmonics – Distortions in the electrical waveform that can affect power quality.

These terms cover a wide range of concepts from basic electrical theory to components and safety practices in electrical systems.
 

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Ampere’s Law describes the relationship between magnetic fields and electric currents, a fundamental concept in electromagnetism. It explains how current produces a magnetic force, guiding the design of circuits, solenoids, coils, and transformers in electrical engineering.

What is Ampere’s Law?

Ampere's Law is a fundamental principle in electromagnetism that describes the relationship between electric current and the resulting magnetic field.

✅ It states that the magnetic field around a closed path is proportional to the electric current passing through it.

✅ It is a fundamental principle of electromagnetism, linking current and magnetic flux.

✅ Used in analyzing coils, solenoids, transformers, and magnetic circuits.

Named after the French physicist André-Marie Ampère, this powerful principle helps us understand the behaviour of magnetic fields generated by electric currents. It is crucial to develop the numerous technologies we use on a daily basis. Understanding Ampere's Law is easier when explored alongside related concepts in basic electricity, which provide the foundation for electrical theory.

The principle states that the line integral of a magnetic field (B) around a closed loop is equal to the product of the permeability of free space (μ₀) and the net electric current (I) passing through the loop. This can be mathematically represented as:

∮ B⋅dl = μ₀I

Ampere’s Law at a Glance

Ampere’s Law and Magnetism

The principle can be applied to determine the magnetic field around current-carrying wires and other conductive materials, as well as within various electrical systems. It is an essential part of Maxwell's equations, a set of four equations that serve as the foundation of classical electromagnetism. These equations relate electric and magnetic fields to their sources (electric charges and currents) and describe how they propagate through space. The connection between electricity and magnetism is central to electromagnetism, where Ampere’s Law works hand-in-hand with Faraday’s Law to explain induction.

It calculates magnetic fields through the Biot-Savart Law, a mathematical expression that relates the magnetic field produced by a steady electric current to the current's geometry. Both principles have specific applications, with the Biot-Savart Law being more suitable for cases with intricate current configurations. At the same time, it is typically employed when dealing with symmetrical setups.

Ampere’s Law has numerous real-life applications, especially in developing and understanding devices and systems that involve electromagnetism. For example, it is used in the design of transformers, inductors, and solenoids, as well as in various applications such as telecommunications systems, motors, and generators. By applying it, engineers can predict and control the magnetic fields generated in these devices, ensuring they function optimally and efficiently.

Gauss’ Law and Electric Fields Around a Circle of Radius

When studying electromagnetism, a common problem is analyzing the behavior of electric fields around a symmetric object, such as a circle of radius r or a sphere. Gauss’ Law is especially powerful in such cases, because it states that the electric flux through a closed surface is proportional to the net charge enclosed. This means the distribution of field lines can be calculated without solving complex integrals directly.

For a uniformly charged circle of radius r, the electric field at a point along the axis can be derived by considering the superposition of contributions from each charge element. The result reveals that the electric field depends on both the radius of the circle and the distance from the observation point. This demonstrates how Gauss’ Law simplifies problems with high symmetry.

Mathematically, the relationship is expressed as:

∮ E · dA = Q / ε₀

Here, E represents the vector field of the electric field, dA is the infinitesimal area vector on the closed surface, Q is the enclosed charge, and ε₀ is the permittivity of free space. By applying this principle, one can determine that electric fields radiate symmetrically outward from charges, with strength diminishing with distance according to the geometry of the surface considered.

The application of Gauss’ Law in analyzing a circle of radius r is connected to Ampere’s Law, as both emphasize symmetry and integration around closed paths. Where Ampere’s Law links magnetic fields to current, Gauss’ Law links electric fields to charge, and together they form part of Maxwell’s equations, the foundation of electromagnetism.

Relationship between Ampere's Law and Faraday's Law

The relationship between Ampere's Law and Faraday's Law of electromagnetic induction is apparent in the phenomenon of electromagnetic induction itself. When a changing magnetic field induces an electric current in a conductive material, the resulting magnetic field generated by this electric current, in turn, affects the overall magnetic field. It helps us understand how these interacting magnetic fields behave and influence each other.

Ampere's Law and its applications in various devices and systems enable numerous technological advancements. For instance, when designing motors and generators, engineers can utilize the principle to optimize the magnetic field within the device, resulting in higher efficiency and improved performance. Ampere’s Law is also linked to the behavior of capacitance and inductance, both of which are essential in circuits and energy storage systems.

In the telecommunications realm, it helps explain the propagation of electromagnetic waves in cables and antennas. It enables engineers to design systems that minimize signal loss and maximize data transfer rates, ensuring that our smartphones, computers, and other devices remain connected and up-to-date.

By understanding the magnetic field lines and the interaction between electric current and magnetic fields, Ampere's Law opens doors to scientific discovery and innovation in numerous fields. From determining the magnetic field at a distance to the thumb rule and hand rule applications, this fundamental principle plays a crucial role in shaping the world of electromagnetism and the technology that surrounds us.

Electromagnetism

It is a cornerstone of electromagnetism that helps us understand the relationship between electric current and how it creates a magnetic field. It is a vital component of Maxwell's equations and intricately connected to other principles, such as Faraday's Law and Biot-Savart's Law. Ampere's Law has numerous applications in real-life scenarios and is essential for the functioning of many devices and systems that rely on electromagnetism. Its significance in the development of technology cannot be overstated, as it continues to drive scientific discovery and innovation. For students exploring fundamentals, the history of concepts like what is electricity and its evolution in electricity history provides valuable context to Ampere’s discoveries.

How does Ampere’s Law relate to Faraday's Law and Biot-Savart Law?

They are all essential principles in electromagnetism that describe various aspects of the interaction between electric currents and magnetic fields. Although each addresses different aspects, these are interrelated, forming a more comprehensive understanding of electromagnetism.

It describes the relationship between an electric current and its generated magnetic field. Mathematically, it states that the line integral of the magnetic field (B) around a closed loop is proportional to the net electric current (I) passing through the loop:

∮ B⋅dl = μ₀I

Ampere’s Law is useful for calculating magnetic fields in highly symmetrical situations, such as around straight wires, loops, or solenoids.

Faraday's Law: Faraday's Law of Electromagnetic Induction describes how a changing magnetic field induces an electromotive force (EMF) in a conductor. Mathematically, it states that the induced EMF is proportional to the rate of change of the magnetic flux (ΦB) through a closed loop formed by the conductor:

EMF = -dΦB/dt

Faraday's Law is fundamental to understanding the operation of devices such as generators, transformers, and induction motors, which rely on converting mechanical and electrical energy.

The Biot-Savart Law calculates the magnetic field at any point in space due to a specific current distribution. Mathematically, it can be expressed as:

dB = (μ₀ / 4π) * (Idl × r̂) / r²

The Biot-Savart Law is particularly useful for calculating magnetic fields in complex current configurations without symmetry.

Ampere's Law and Biot-Savart Law

Ampere's Law and Biot-Savart Law: Both deal with the magnetic field generated by an electric current. While the first is useful for calculating magnetic fields in symmetric situations, the Biot-Savart Law applies to a wider range of configurations, including those with intricate geometries. It can be derived from the Biot-Savart Law for specific symmetric situations.

Ampere's Law and Faraday's Law

Ampere's Law and Faraday's Law: These laws are related through Maxwell's equations, which connect electric and magnetic fields. While the first deals with the magnetic field generated by a steady electric current, Faraday's Law deals with the induced EMF resulting from a changing magnetic field. Both laws contribute to our understanding of electromagnetic phenomena and play a role in operating devices that rely on electromagnetism.

The Biot-Savart Law enables us to determine the magnetic field generated by a specific current distribution. Faraday's Law describes how a changing magnetic field can induce an EMF. In cases where the magnetic field changes due to a varying current, the Biot-Savart Law can be used to calculate the magnetic field, and then Faraday's Law can be applied to determine the induced EMF.

All three are interconnected principles in electromagnetism, each addressing a specific aspect of the interaction between the electric current and the electric field. Together, these form a more comprehensive understanding of electromagnetic phenomena and provide a basis for analyzing and designing various devices and systems that rely on electromagnetism.

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Electricity safety in electrical engineering prioritizes grounding, insulation coordination, overcurrent protection, arc-flash mitigation, lockout/tagout, and PPE to reduce shock, burn, and fire hazards in high-voltage and low-voltage installations through standards compliance and risk assessment.

What Is Electricity Safety?

Electricity safety is engineering practice to prevent shock, arc flash, and fire through design, controls, and standards.

✅ Implement grounding/earthing, bonding, and insulation coordination.

✅ Use overcurrent, residual current, and arc-fault protection.

✅ Apply NFPA 70E/IEC 60364, lockout/tagout, and arc-flash PPE.

Electricity Safety dangers involving voltages of greater than 50V are capable of producing heart fibrillation if they produce electric currents in body tissues which happen to pass through the chest area. The electrocution danger is mostly determined by the low conductivity of dry human skin. If skin is wet, or if there are wounds, or if the voltage is applied to electrodes which penetrate the skin, then even voltage sources below 40 V can be lethal if contacted. A DC circuit may be especially dangerous because it will cause muscles to lock around the wire. For a broader overview of common electrical hazards, the guide at dangers of electricity explains mechanisms of shock and injury.

Accidental contact with high voltage will usually result in severe injury or death. This can occur as a person's body provides a path for current flow causing tissue damage and heart failure. Other injuries can include burns from the arc generated by the accidental contact. These can be especially dangerous if the victims airways are affected. Injuries may also be suffered as a result of the physical forces exerted as people may fall fall from height or be thrown considerable distance. For context on regulatory and industry thresholds, see what is considered high voltage and how those limits are defined.

Electricity Safety

Depending on the short circuit current available at a switchgear line-up, a hazard is presented to maintenance and operating personnel due to the possibility of a high-intensity electric arc. Maximum temperature of an arc can exceed 10,000 kelvin, and the radiant heat, expanding hot air, and explosive vaporization of metal and insulation material can cause severe injury to unprotected workers. Such switchgear line-ups and high-energy arc sources are commonly present in electric power utility substations and generating stations and power lines, industrial plants and large commercial buildings. In the United States the National Fire Protection Association, has published a guideline standard NFPA 70E for evaluating and calculating arc flash hazard, and provides standards for the protective clothing required for electrical workers exposed to such hazards in the workplace. And even then, workers must still be careful. Understanding fault energy begins with the basics of a short circuit and how fault paths escalate incident energy.

While arc flash and arc blast are distinct, an arc fault can originate from insulation breakdown or wiring damage and quickly intensify conditions.

Explosion hazard

Even voltages insufficient to break down air can be associated with enough energy to ignite atmospheres containing flammable gases or vapours, or suspended dust. For example, air containing hydrogen gas or natural gas or gasoline vapor can be ignited by sparks produced by electrical apparatus fed by electricity lines or electricity power lines. Examples of industrial facilities with hazardous areas are petrochemical refineries, chemical plants, grain elevators, and some kinds of coal mines. In many environments, seemingly minor static electricity discharges are sufficient to ignite vapors if controls are inadequate.

Measures taken to prevent such explosions include:

• Intrinsic safety, which is apparatus designed to not accumulate enough stored energy to touch off an explosion
• Increased safety, which applies to devices using measures such as oil-filled enclosures to prevent contact between sparking apparatus and an explosive atmosphere
• Explosion-proof enclosures, which are designed so that an explosion within the enclosure cannot escape and touch off the surrounding atmosphere (this designation does not imply that the apparatus will survive an internal or external explosion).

In recent years standards for explosion hazard protection have become more uniform between European and North American practice. The "zone" system of classification is now used in modified form in U.S. National Electrical Code and in the Canadian electrical code. Intrinsic safety apparatus is now approved for use in North American applications, though the explosion-proof enclosures used in North America are still uncommon in Europe. For clarity on terminology used across these standards, consult this electricity terms glossary for consistent definitions.

The Electric Safety Home is a home in which the outlet plugs, electric cords, and each electricity plug and cord plug near sinks and water sources are GFCI protected. That makes them safe. Understanding the nature of a ground fault helps explain why GFCIs trip quickly to prevent shock.

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