TP EIMSA case studies
TP EIMSA · Put your knowledge to work in context.
TP EIMSA is a professional electrical trade credential for practitioners who install, maintain, inspect and troubleshoot electrical systems and who must work to recognised codes and safety standards. Candidates are typically electricians, maintenance technicians, installation supervisors and inspection personnel who need to demonstrate both practical competence and command of the standards that govern their work. The TP EIMSA case studies are 5 cases and about 4,680 words.
1Nuisance Tripping of an Origin RCD on a Kitchen Board with VFD Loads
A four-star hotel reports that the 300 mA Type AC residual current device at the origin of the TN-S kitchen distribution board trips two or three times a week, always within about ten minutes of the breakfast shift starting. The board feeds twelve final circuits: four 30 mA RCBOs for socket outlets, direct-on-line combi ovens, a 15 kW dishwasher, and an extract hood fan driven by a 7.5 kW variable-speed drive on a 45 m motor cable.
960 words, about 5 min2Motor Feeder Insulation Resistance and Polarization Index at Commissioning
A 200 kW, 400 V three-phase cage induction motor is being commissioned on an industrial site. The feeder is a 4 × 185 mm² copper XLPE/SWA cable, 120 m long, run on a tray with two other loaded cables.
910 words, about 5 min3Cable Derating and Voltage Drop on a Long Ceiling-Void Submain
A workshop submain runs 95 m from the main LV switchboard to a distribution board in a ceiling void. The load is 250 A three-phase, 400 V, power factor 0.85, and the designer has selected a single 4-core 95 mm² copper XLPE/SWA cable.
916 words, about 5 min4Neutral Current Exceeding Phase Current in an Office Submain
A three-phase four-wire TN-S submain feeds thirty workstation clusters in an open-plan office at 400/230 V. Both the line conductors and the neutral are 70 mm² copper, protected upstream by a 160 A moulded-case circuit breaker.
920 words, about 5 min5Periodic Inspection Findings at an Ageing Factory Intake
A periodic inspection is carried out on a 30-year-old factory with a 100 A three-phase TN-C-S supply. The intake has a 25 mm² earthing conductor, while the water service main protective bonding conductor is only 6 mm².
974 words, about 5 min