Memory SNC1D - Drawing Circuit SymbolsVersión en línea Drawing symbols for circuits. por Ms. S Munawar Ammeter: measures current, Connected in series. Switch: opens and closes the circuit. Fuse: Safety device that has a metal conductor which melts at high, dangerous current levels. Wire: conductor, allows electrons to flow. Battery: electrical energy source. Voltmeter: measures voltage. Connected in parallel. Resistor: general load, converts electricity to heat. Lamp/light bulb: specific load, converts electricity to light and heat.