The technique is used in situations such as ECGs[2] and precision low-current measurement where leakage current would otherwise swamp or alter the measurement. Any situation in which the source to be measured has a very high output impedance is vulnerable to leakage current and if sufficient insulation is not practical then a driven shield will improve performance. Coaxial cable is well suited for use as a guard, if electromagnetic shielding is also required then triaxial cable should be used as depending on the type of buffer circuit any noise on the guard may be amplified in the output.[3]