We demonstrate a low-crosstalk 2 x 2 thermo-optic switch with silicon wire waveguides. The device is based on a 2 x 2 array of Mach-Zehnder interferometer (MZI) switches. Lowest crosstalk levels of -50 dB and -30 dB are obtained for 'bar' and 'cross' switching states, respectively. An intersection in the switch is important for low-crosstalk operation. The power consumption of one MZI element switch is 40 mW and the total power consumption of the device is at most 160 mW.