I recently came across a double ended 480 service entance switchboard with both mains closed and the tie open. surge protection is installed on both service entances. Each surge protector is equipped with a surge counter. The surge counter from one substation recorded around 10 surges, the...
Does anyone know whether ANSI constructed transformers have a tolerance associated with the impedance value stamped on the nameplate?
I am aware ANSI standards allow a +/- 7.5% design tolerance and that UL constructed transformers can have an impedance of +/-10% of the value stamped on the...
I was recently reviewing a ground grid study for an indoor installation and saw something that struck me as odd. The ground grid is installed beneath the basement, air cured, concrete floor of a building. There is steel re-bar inside the concrete slab. Yet the study still lists the resistance...
