A coupling interface for establishing an electrical coupling with an electrically conductive article, wherein the coupling interface is adapted to control a plurality of conductive regions (311, 312, 313, 314), each conductive region being switchably coupled (301a, 301b, 301c, 301d) under the control of said coupling interface to a first voltage, said coupling interface further comprising a controller configured to sequentially select each said region and to switch said selected region to said first voltage, wherein each of said plurality of regions other than said selected region is coupled in a measurement condition to a second voltage, said second voltage defining a first potential difference with respect to said first voltage via a respective known resistance, wherein said coupling interface is further adapted to measure a voltage of each of said plurality of regions other than said selected region across each respective known resistance, and to compare each said region voltage to one or more first reference voltage ranges, each said first reference voltage range corresponding to a specified class of electrical device, said coupling interface characterized in that, in a case where a said region voltage falls within a first short circuit voltage range, said interface being adapted to further couple said selected region to a fifth voltage via the respective known resistance, and to switch the respective said region other than said selected region to a sixth voltage, said sixth voltage defining a potential difference with respect to said fifth voltage of opposite polarity to the potential difference defined by said second voltage with respect to said first voltage, and to measure said voltage of said selected region, and in a case where the voltage of said selected region lies in a second short circuit voltage range, considering said article to be a conductive article creating a short circuit between said selected region and the respective said region in a measurement condition and otherwise in a case where any said region voltage corresponds to a respective one of said first reference voltage ranges, to establish respective persistent electrical connections to said selected region and said respective region other than said selected region having a region voltage corresponding to said respective one of said first reference voltage ranges by controlling said switchable coupling (301a, 301b, 301c, 301d) accordingly. wherein the coupling interface is adapted to control a plurality of conductive regions (311, 312, 313, 314), each conductive region being switchably coupled (301a, 301b, 301c, 301d) under the control of said coupling interface to a first voltage, said coupling interface further comprising a controller configured to sequentially select each said region and to switch said selected region to said first voltage, wherein each of said plurality of regions other than said selected region is coupled in a measurement condition to a second voltage, said second voltage defining a first potential difference with respect to said first voltage via a respective known resistance, wherein said coupling interface is further adapted to measure a voltage of each of said plurality of regions other than said selected region across each respective known resistance, and to compare each said region voltage to one or more first reference voltage ranges, each said first reference voltage range corresponding to a specified class of electrical device, said coupling interface characterized in that, in a case where a said region voltage falls within a first short circuit voltage range, said interface being adapted to further couple said selected region to a fifth voltage via the respective known resistance, and to switch the respective said region other than said selected region to a sixth voltage, said sixth voltage defining a potential difference with respect to said fifth voltage of opposite polarity to the potential difference defined by said second voltage with respect to said first voltage, and to measure said voltage of said selected region, and in a case where the voltage of said selected region lies in a second short circuit voltage range, considering said article to be a conductive article creating a short circuit between said selected region and the respective said region in a measurement condition and otherwise in a case where any said region voltage corresponds to a respective one of said first reference voltage ranges, to establish respective persistent electrical connections to said selected region and said respective region other than said selected region having a region voltage corresponding to said respective one of said first reference voltage ranges by controlling said switchable coupling (301a, 301b, 301c, 301d) accordingly.