A current shunt is a high current, low resistance, resistor which is placed in series with the current flow to allow external devices to measure the current. Each current shunt will be calibrated to drop a certain voltage in relation to the current.

E.g. when a 100A/50mV current shunt has 10 mV across it, then the current will be read as 20 Amps. Current shunts are only used in DC circuits.

When using current shunts, it is recommended to size the shunt allowing for at least 40% extra than the maximum expect current.