# Why no extension cords?

**URL:** <https://boards.straightdope.com/t/why-no-extension-cords/542640>\
**Category:** Factual Questions\
**Created:** [June 10, 2010, 12:26pm UTC](https://boards.straightdope.com/t/why-no-extension-cords/542640 "2010-06-10T12:26:01Z")\
**Posts on this page:** 1\
**Page:** 4

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**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\
**Post date:** [July 17, 2017, 12:23am UTC](https://boards.straightdope.com/t/why-no-extension-cords/542640/61 "2017-07-17T00:23:54Z")

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> [@watchwolf49](#):
>
> extension cords that are listed will have thicker insulation and be more resistant to mechanical damage … plus the store bought ones are made of stranded wire instead of solid wire so they’re easier to manage

Agree.

I believe one the specs for an outdoor-rated extension cord is that it must be able to withstand being run over by a typical car when laid across concrete. (I should check on this.) Hence the thick PVC jacket. The jacket material is also formulated to be moisture-resistant and UV-resistant, and is constructed to withstand a certain amount of tension. And as you mentioned, 12/2 NM-B (“Romex”) consists of solid conductors. It is not flexible and could break due to fatigue.

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