A split-core current measurement device comprising: a first arm including a first magnetic core portion ; a second arm including a second magnetic core portion; a first sensing element sensitive to changes in magnetic field; the first and second magnetic core portions being shaped so that, when the first and second arms of the measurement device are in a closed configuration, the first and second magnetic core portions cooperate to form a substantially complete magnetic circuit configured to act as a flux guide when the measurement device surrounds a current carrying conductor ; wherein the first magnetic core portion includes a first non-magnetic core discontinuity; and wherein the first magnetic core portion defines a first internal cavity within which the first sensing element is contained such that at least a portion of the first sensing element is located in the first non-magnetic core discontinuity, the first magnetic core portion comprises separate first and second sectors , wherein a first end of the first sector and a first end of the second sector are separated by a non-magnetic clearance (C) due to the presence of the first non-magnetic core discontinuity, and characterised in that the clearance (C) between the first end of the first sector and the first end of the second sector is less than i) a clearance (R1) between the first end of the first sector and a first magnetic shield portion of the first arm, and/or ii) a clearance (R2) between the first end of the second sector and the first magnetic shield portion , to thereby reduce flux leakage between the first magnetic core portion and the first magnetic shield portion. a first arm including a first magnetic core portion ; a second arm including a second magnetic core portion; a first sensing element sensitive to changes in magnetic field; the first and second magnetic core portions being shaped so that, when the first and second arms of the measurement device are in a closed configuration, the first and second magnetic core portions cooperate to form a substantially complete magnetic circuit configured to act as a flux guide when the measurement device surrounds a current carrying conductor ; wherein the first magnetic core portion includes a first non-magnetic core discontinuity; and wherein the first magnetic core portion defines a first internal cavity within which the first sensing element is contained such that at least a portion of the first sensing element is located in the first non-magnetic core discontinuity, the first magnetic core portion comprises separate first and second sectors , wherein a first end of the first sector and a first end of the second sector are separated by a non-magnetic clearance (C) due to the presence of the first non-magnetic core discontinuity, and characterised in that the clearance (C) between the first end of the first sector and the first end of the second sector is less than i) a clearance (R1) between the first end of the first sector and a first magnetic shield portion of the first arm, and/or ii) a clearance (R2) between the first end of the second sector and the first magnetic shield portion , to thereby reduce flux leakage between the first magnetic core portion and the first magnetic shield portion. <EOS>