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Why are the two wires to the H2N electrode contacts twisted, and does it affect the 2-wire principle?

While H2 electrode contacts without net have untwisted wires in line with the 2-wire principle, the H2N contacts have wires twisted close to the hand+net. This is necessary to prevent the net from getting detached by movements of the two wires. The twisting thus has the function to stabilize the contact. Electrically speaking, there is no significant difference between contacting the two wires at the twist or a few millimeters later at the net. The untwisted configuration has in principle the advantage of cancelling any resistance in the remaining 2-3 mm of the Pt. But the twisted configuration has the advantage of getting a well-defined point of common voltage and current. In the worst case, and untwisted H2 can have several contact points to the sample where the local voltages and currents are slightly different. In both cases, it is the resistance of Pt over a few mm which is the cause of the behaviours, which for all realistic purposes will be negligible. The important thing is that both the twisted and untwisted contacts represents 2 wires all the length of 40-50 cm up the hot zone of the ProboStat, hence canceling all that resistance in the Pt wires.

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