lightning rod

lightning rod
1. a rodlike conductor installed to divert lightning away from a structure by providing a direct path to the ground.
2. a person or thing that attracts and absorbs powerful and esp. negative or hostile feelings, opinions, etc., thereby diverting such feelings from other targets: The unpopular supervisor served as a lightning rod for the criticism that should have been aimed at management.
[1780-90, Amer.]

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 metallic rod (usually copper) that protects a structure from lightning damage by intercepting flashes and guiding their currents into the ground. Because lightning tends to strike the highest object in the vicinity, rods are typically placed at the apex of a structure and along its ridges; they are connected to the ground by low-impedance (electrical impedance) cables. In the case of a building, the soil is used as the ground; on a ship, the water is used.

 A lightning rod and its associated grounding conductors provide protection because they divert the current from nonconducting parts of the structure, allowing it to follow the path of least resistance and pass harmlessly through the rod and its cables. It is the high resistance of the nonconducting materials that causes them to be heated by the passage of electric current, leading to fire and other damage. On structures less than 30 metres (about 100 feet) in height, a lightning rod provides a cone of protection whose ground radius approximately equals its height above the ground. On taller structures, the area of protection extends only about 30 metres from the base of the structure.
 

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Universalium. 2010.

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Look at other dictionaries:

  • Lightning rod — Lightning Light ning (l[imac]t n[i^]ng), n. [For lightening, fr. lighten to flash.] 1. A discharge of atmospheric electricity, accompanied by a vivid flash of light, commonly from one cloud to another, sometimes from a cloud to the earth. The… …   The Collaborative International Dictionary of English

  • lightning rod — lightning rods 1) N COUNT A lightning rod is the same as a lightning conductor. [AM] 2) PHRASE: PHR n If you say that someone is a lightning rod for something, you mean that they attract that thing to themselves. [AM] He is a lightning rod for… …   English dictionary

  • lightning rod — lightning .rod n AmE 1.) a ↑lightning conductor 2.) someone or something who gets most of the criticism, blame, or public attention when there is a problem, although they may not be responsible for it be a lightning rod for sth ▪ The senator has… …   Dictionary of contemporary English

  • lightning rod — lightning ,rod noun count AMERICAN 1. ) a metal bar fixed to a building that protects it from LIGHTNING 2. ) someone who attracts a lot of criticism, sometimes as a way of protecting someone else: The outspoken chief inspector serves as a… …   Usage of the words and phrases in modern English

  • lightning rod — Someone or something that attracts a lot of negative comment, often diverting attention from other problems, is a lightning rod …   The small dictionary of idiomes

  • lightning rod — ☆ lightning rod n. 1. a tall metal pole placed high on a structure, as a building or tower, and attached to a ground so as to attract lightning and protect the structure from damage 2. a person or thing that attracts controversy, strong feelings …   English World dictionary

  • Lightning rod — A lightning rod (USA) or lightning conductor (UK) is a single component in a lightning protection system. In addition to rods placed at regular intervals on the highest portions of a structure, a lightning protection system typically includes a… …   Wikipedia

  • lightning rod — noun Date: 1773 1. a grounded metallic rod set up on a structure (as a building) to protect it from lightning 2. one that serves to divert attack from another 3. one that is a frequent target of criticism or focus of controversy < she has become… …   New Collegiate Dictionary

  • lightning rod — /ˈlaɪtnɪŋ rɒd/ (say luytning rod) noun 1. → lightning conductor. 2. someone or something which attracts heated debate: an agreement which is a lightning rod for both sides of politics …  

  • lightning rod — n. someone, something, or an issue that is certain to draw criticism. □ Why write such a boastful introduction to your book? It will just be a lightning rod for criticism. □ We didn’t hire him for the part since his opinionated comments make him… …   Dictionary of American slang and colloquial expressions

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