Electrical resistivity tomography Electrical resistivity tomography Electrical resistivity tomography (ERT) or electrical resistivity imaging (ERI) is a geophysical technique for imaging sub-surface structures from electrical resistivity measurements made at the surface, or by electrodes in one or more boreholes. If the electrodes are suspended in the boreholes, deeper sections can be investigated. It is closely related to the medical imaging technique electrical impedance tomography (EIT), and mathematically is the same inverse problem. In contrast to medical EIT, however, ERT is essentially a direct current method. A related geophysical method, induced polarization (or spectral induced polarization), measures the transient response and aims to determine
Electrical room that handle flammable gases or liquids, or combustible dusts, special electrical rooms may be prepared that have ventilation and other measures to prevent an explosion hazard that would otherwise exist with electrical equipment in hazardous areas. For large installations, it may be less costly overall to use a special room than to install a large number of devices that are resistant to the hazardous conditions. Similarly, in wet or corrosive environments, electrical equipment may be separated in a room that can be protected from the atmospheric conditions. Building code and electrical code regulations will dictate minimal working space around equipment