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Current leads, which connect superconducting magnets at the liquid helium temperature and power supplies at the room temperature, are the major source of heat leaking into cryostats, and therefore largely determines the running cost of magnet systems. Heat leak can be reduced by using high-temperature superconductors as the low-temperature (4 K-77 K) segments of current leads. Another method to reduce heat leakage, recently proposed, uses Peltier thermoelectric elements as the high-temperature (200 K-300 K) segments of current leads. These thermoelements effectively pump heat out of cryostats without using separate sources of electricity. The authors carried out experiments and numerical calculations with such Peltier current leads and found out that they reduce heat leak at 77 K by 20-30 percent.