Fuse symbol with TikZ

Question

I am using the circuits.ee.IEC library. However, I cannot find any fuse symbol like this:

How can I define such a symbol using circuit declare symbol? It should be just combining the resistor symbol and a line in some way, but I don't understand the syntax well enough to do this.

Answer 1

A different approach would be to append code after the resistor node, similar to the light emitting and direction info styles:

\documentclass{standalone}

\usepackage{tikz}
\usetikzlibrary{circuits.ee.IEC}

\begin{document}

\tikzset{
    fuse graphic/.style={
        append after command={% At the end of the \draw command, do the following
            \bgroup % Start a new group
                [current point is local=true, % Do not influence the current point on the path
                every fuse/.try, % If `every fuse` has been defined, use it
                #1] % Apply options supplied by user
                (\tikzlastnode.west) edge [line to] (\tikzlastnode.east) % An edge, i.e. an independent path, from the west to the east of the resistor node
            \egroup% End the group
        }
    },
    fuse/.style={resistor={fuse graphic=#1}} % The fuse is just a resistor node with the `fuse graphics` key
}


\begin{tikzpicture}[circuit ee IEC]
    \draw (0,0) to [fuse] (2,0)  to [fuse] (0,-2) to [fuse] (0,0);
  \end{tikzpicture}


\end{document}

Answer 2

You can use annotations as described in the TikZ/PGF manual in Section 29.2.5 Declaring and Using Annotations to add the horizontal line over the symbol:

Annotations are quite similar to info labels. The main difference is that they generally cause something to be drawn by default rather than some text to be added (although an annotation might also add some text).

Here is an example of resistor and the fuse that you want:

Notes:

• This is my first attempt with annotations, and I am not sure about the coordinates used in the edge operation below. As per the comment by @GonzaloMedina, I have tweaked the coordinates by (0,-0.5\pgflinewidth) to adjust for the width of the rule. However, this still seems a bit of hack and feel that there should be a better way.
• The transform shape option is what makes the fuse points along the path.

Code:

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{circuits.ee.IEC}

\tikzset{circuit declare annotation=
    {HorizontalAnnotation}
    {0pt}
    {edge[to path={[-]
            ($(-0.5,-0.5\tikzcircuitssizeunit)+(0,-0.5\pgflinewidth)$) 
        --  ($( 0.5,-0.5\tikzcircuitssizeunit)+(0,-0.5\pgflinewidth)$)}] ()}
}

\tikzset{circuit declare symbol=fuse, 
    set fuse graphic={
        draw,
        circuit symbol size=width 4 height 1, 
        HorizontalAnnotation
    }, 
    transform shape}

\begin{document}
  \begin{tikzpicture}[circuit ee IEC]
    \draw (0,1.0) to [resistor] (3,1.0) node [right] {resistor};
    \draw (0,0.5) to [fuse]     (3,0.5) node [right] {fuse};
    \draw (0,0.5) to [fuse] (0,-2) to [fuse] (3,0.5);
  \end{tikzpicture}
\end{document}