electrical wiring diagram, <a href="https://en.wikipedia.org/wiki/fusebox" class="extiw" title="w:fusebox">fusebox</a> and <a href="https://en.wikipedia.org/wiki/switch" class="extiw" title="w:switch">switch</a> and lamp
<a href="//commons.wikimedia.org/wiki/User:Sunspeanzler" title="User:Sunspeanzler">Sunspeanzler</a>
<span class="int-own-work" lang="en">Own work</span>