An electrically heated tubing bundle includes one or more tubes configured to allow a fluid to flow therethough, and an electrical resistance heater. The electrical resistance heater includes a plurality of heater wires each having a predetermined electrical resistance, the heater wires extending along at least a portion of the one or more tubes, one or more power wires connected to a power supply, and a connection system having a plurality of input and power leads at a power side of the connection system and a plurality of output and return leads at a probe side of the connection system. The one or more power wires are connected to respective power and input leads. Each heater wire is configured for selective electrical connection to an input and power lead and an output and return lead which form lead pairs for each heater wire, such that a plurality of different circuit configurations for the electrical resistance heater are provided based on electrical connections between the heater wires and the lead pairs.