sentences:  Ungrounded metal objects close to electric field sources such as neon signs or conductors carrying alternating currents can have measurable voltage levels caused by capacitive coupling.Since voltages detected by high-impedance instruments disappear or become greatly reduced when a low impedance is substituted, the effect is sometimes called phantom voltage (or ghost voltage).The term is often used by electricians, and might be seen, for example, when measuring the voltage at a lighting fixture after removing the bulb.