Glossary of surge protection terms

Many of these descriptions are provided courtesy of Google, Wikipedia and Friends. If there are any suggestions or changes required, please contact us.


The definition of amp is an abbreviation for ampere which is the basic unit of measurement for electricity. The higher the value, the more powerful the charge.


American Wire Gauge, also known as the Brown & Sharpe wire gauge, is a logarithmic stepped standardized wire gauge system used since 1857, predominantly in North America, for the diameters of electrically conducting wire. Dimensions of the wire thickness are given in a range of numbers 0-40 where 40 is the thinnest and 0 is the thickest.


The Cat, as you might know, is short for "Category." The term "Category" refers to the different levels of performance in signal bandwidth, attenuation and crosstalk associated with each cable's design. Category 5, 5e, 6, 6a cables are twisted pair cables for computer networks. Since 2001, the variant commonly in use is the Category 5e specification (Cat 5e). 



Clamping voltage indicates the voltage level at which the surge protector will activate and reduce the surge. A low clamping voltage of 500 volts or less is preferred. One nanosecond or less reaction time is ideal.


Coaxial cable, or coax is a type of electrical cable consisting of an inner conductor surrounded by a concentric conducting shield, with the two separated by a dielectric; many coaxial cables also have a protective outer sheath or jacket.


A unit of electric charge equal to the quantity of electricity transferred by a current of one ampere in one second.


An electric current is the number of charged electrons flowing in a circuit per second forced by voltage “pressure”.


Electrical Fast Transients (EFT), also going by fast transients or bursts (EFT/B) are a series of quick high frequency pulses mainly caused by arching (sparking). A common cause of power line transients occurs when an AC/DC connection is made or broken, equipment powered down, or circuit breakers switched.


An electromagnetic pulse (EMP), also sometimes called a transient electromagnetic disturbance, is a short burst of electromagnetic energy.


Electrostatic discharge (ESD) is a swift discharge of electric current between two objects with different charges and different numbers of electrons. This exchange of electrons creates a large electromagnetic field buildup, resulting in ESD. Certain electronic devices are vulnerable to low-voltage ESD. For example, a hard drive is susceptible to just 10 volts. Integrated circuits (IC) are also prone to ESD and may be permanently damaged by high-voltage currents.


Ethernet is a family of wired computer networking technologies commonly used in local area networks, metropolitan area networks and wide area networks. It was commercially introduced in 1980 and first standardized in 1983 as IEEE 802.3. 


Gas discharge tubes dissipate voltage transients through a contained plasma gas. They have high insulation resistance plus low capacitance and leakage to ensure minimal effect on normal operation of equipment. They are used in SPDs to prevent power surges.


In electrical speak, ground or earth is a reference point in an electrical circuit providing a common return path for electric current, or a direct physical connection to the earth. Electrical circuits may be connected to ground for several reasons, primarily to divert excess electric current.


High-Definition Multimedia Interface is a proprietary audio/video interface for transmitting uncompressed video data and compressed or uncompressed digital audio data from an HDMI-compliant source.


HVAC stands for Heating, Ventilation, and Air Conditioning. HVAC refers to the different systems used for moving air between indoor and outdoor areas, along with heating and cooling both residential and commercial buildings.


A unit of work or energy equal to the work done by a force of one newton acting through one meter. Named in honor of the English physicist James Prescott Joule


A nanosecond is a unit of time equal to one billionth of a second.


The neutral wire carries the circuit back to the original power source. More specifically, neutral wire brings the circuit to a ground or busbar usually connected at the electrical panel. This gives currents circulation through your electrical system, which allows electricity to be fully utilized.




Power over Ethernet, or PoE, describes any of several standards or ad hoc systems that pass electric power along with data on twisted-pair Ethernet CAT cabling. This allows a single cable to provide both data connection and electric power to devices such as wireless access points (WAPs), Internet Protocol (IP) cameras, and voice over Internet Protocol (VoIP) phones. The + and ++ indicate the different IEEE standard supported and the level of power that may be transmitted i.e. POE supports 15.4 watts, POE+ 30 watts, and POE++ 60-100 watts. This dictates the level of device power requirement that may be supported. Note that POE++ and POE+ standards are backward compatible with the previous versions e.g. POE++ will also support POE+ and POE devices.


An 8-pin/8-position plug, or jack is commonly used to connect computers onto Ethernet-based local area networks (LAN).


Surge Protection Device used to protect electrical circuits from voltage and power spikes.


An uninterruptible power supply or uninterruptible power source (UPS) is an electrical apparatus that provides emergency power to a load when the input power source or mains power fails. A UPS differs from an auxiliary or emergency power system or standby generator in that it will provide near-instantaneous protection from input power interruptions, by supplying energy stored in batteries, supercapacitors, or flywheels. The on-battery run-time of most uninterruptible power sources is relatively short (only a few minutes) but sufficient to start a standby power source or properly shut down the protected equipment. It is a type of continual power system. A UPS is typically used to protect hardware such as computers, data centers, communication equipment or other electrical equipment where an unexpected power disruption could cause injuries, fatalities, serious business disruption or data loss. UPS units’ range in size from units designed to protect a single computer to large units powering entire data centers or buildings.


Voice over Internet Protocol, also called IP telephony, is a method and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol networks, such as the Internet.


A volt measures how much “pressure” there is in an electric circuit. The higher the voltage, the more electrical current will flow in the circuit. One volt equals one joule per coulomb. It is named after the Italian physicist Alessandro Volta.


UL 1449 Voltage Protection Rating (VPR) is a measure of the surge protectors “let-through” voltage, which is the maximum voltage a surge protector will let through to connected devices. The lower the VPR number, the better the protection. Also see “Clamping Voltage”.


The watt is a unit of power, defined as 1 joule per second. It is used to quantify the rate of energy transfer. The watt is named after James Watt, an 18th-century Scottish inventor. Voltage x Amps = Watts.


Additional information:

Download our free Surge Protection PDF.

< Back