\documentclass[border=2pt]{standalone}

% Circuits
\usepackage{circuitikz}

% Notation
\usepackage{siunitx}

% Define Color
\definecolor{bluegray}{rgb}{0.4, 0.6, 0.8}

% Define Lengths
\def\dx{0.3}
\def\dy{0.4667}
\def\x{10.75}
\def\xx{12.0}
\def\y{9.0}

\def\dX{0.6}
\def\dY{1}
\def\X{7.25}
\def\XX{6.0}
\def\Y{9}

\begin{document}
	
	\begin{circuitikz}[scale=0.5]
		% Grid
%		\draw[help lines] (-1,-1) grid (18,14);
		
		% Core (Blue)
		\draw[draw=black, line width = 2pt, fill = bluegray, even odd rule, rounded corners]
			(6, -0.5) rectangle ++(6,12) (7.25, 1) rectangle ++(3.5,9);
		
		% Circuit
		%% Left	
		\draw[line width=1.5pt]
		 (\X,\Y) -- (2,9) to [sV, line width=0.7pt, l_=$V_1$, i=$I_1$] (2,2) -- (\XX,2);
		%% Right 
		\draw[line width=1.5pt]
		 (12,9) to [normal open switch, line width=0.7pt, l=$S$] (16,9)
		  to [R, line width=0.7pt, l=$R_L$, i=$I_2$] (16,2) -- (\xx,2);
		  
		% Nodes
		\node at (8.25,8) {$N_1$};
		\node at (9.75,3) {$N_2$};
		\draw[thick] (11.5,10.75) -- (10, 13) -- (9.5,13) node [left] {$\Phi_B$};
			
		% Cables (Black)	
		%% Left
		\foreach \i in {0,2,4}
		{	
			\draw[line width=1.5pt] (\X,\Y-\i*\dY) ..controls (\X+\dX, \Y-\i*\dY) and (\X+\dX,\Y-\dY-\i*\dY).. (\X,\Y-\dY-\i*\dY);
			
			\draw[line width=1.5pt] (\XX,\Y-\i*\dY-\dY) ..controls (\XX-\dX, \Y-\i*\dY-\dY) and (\XX-\dX,\Y-\i*\dY-2*\dY).. 
								(\XX,\Y-\i*\dY-2*\dY);
								
			\draw[line width=1.5pt] (\XX,\Y-\i*\dY) -- (\X,\Y-\i*\dY);
			
			\draw[line width=1.5pt] (\XX,\Y-\i*\dY-2*\dY) -- (\X,\Y-\i*\dY-2*\dY);
			
			\draw[line width=1.5pt] (\X,\Y-\i*\dY-2*\dY) ..controls (\X+\dX, \Y-\i*\dY-2*\dY) and (\X+\dX,\Y-\dY-\i*\dY-2*\dY).. (\X,\Y-\dY-\i*\dY-2*\dY);

		} 				
		% Right
		\foreach \i in {0,2,4,6,8,10,12}
		{	
			\draw[line width=1.5pt] (\x,\y-\i*\dy) ..controls (\x-\dx, \y-\i*\dy) and (\x-\dx,\y-\dy-\i*\dy).. (\x,\y-\dy-\i*\dy);
			
			\draw[line width=1.5pt] (\xx,\y-\i*\dy-\dy) ..controls (\xx+\dx, \y-\i*\dy-\dy) and (\xx+\dx,\y-\i*\dy-2*\dy).. 
								(\xx,\y-\i*\dy-2*\dy);
								
			\draw[line width=1.5pt] (\xx,\y-\i*\dy) -- (\x,\y-\i*\dy);
			
			\draw[line width=1.5pt] (\x,\y-\i*\dy-2*\dy) ..controls (\x-\dx, \y-\i*\dy-2*\dy) and (\x-\dx,\y-\dy-\i*\dy-2*\dy).. (\x,\y-\dy-\i*\dy-2*\dy);
			
			\draw[line width=1.5pt] (\xx,\y-\i*\dy-2*\dy) -- (\x,\y-\i*\dy-2*\dy);

		} 		
	\end{circuitikz}

	
\end{document}