DM Electrical Exam case studies
DM Electrical Exam · Put your knowledge to work in context.
The DM Electrical Exam is a multiple-choice credentialing assessment for electricians and electrical tradespeople working in the District of Columbia. It is intended to confirm that a candidate can apply electrical theory, code requirements, and safe installation practices on the job, not just recite definitions. The DM Electrical Exam case studies are 5 cases and about 3,403 words.
1Neutral Sizing on a Retrofitted Subpanel
A contractor is adding a 120/240 V single-phase subpanel fed from a 200 A main panel with a 4-wire feeder. The subpanel will supply a 9 kW electric range (nameplate 40 A, 240 V), a 4.5 kW dryer (240 V), six 20 A small-appliance branch circuits, and a 3-ton heat pump with a 25 A minimum circuit ampacity and 40 A maximum overcurrent device.
798 words, about 4 min2GFCI Nuisance Tripping on a Kitchen Circuit
A homeowner reports that a 20 A kitchen countertop receptacle circuit trips its GFCI breaker intermittently, usually when the dishwasher or a countertop appliance runs. The circuit serves eight receptacles, a dishwasher (cord-and-plug, 12 A), and a garbage disposal (1/2 HP).
643 words, about 3 min3Voltage Drop on a Long Barn Feeder
A farm owner wants a 100 A subpanel in a barn 350 ft from the main service. The load is a 5 HP 240 V single-phase motor (nameplate 28 A, 240 V) plus lighting and receptacles totaling 30 A at 120 V.
699 words, about 3 min4Bonding a Corrugated Stainless Steel Gas Line
An electrician is roughing in a new house and notices that the gas piping is corrugated stainless steel tubing (CSST) running through the attic and walls to a tankless water heater, range, and dryer. The plumber has bonded nothing.
631 words, about 3 min5Troubleshooting a Dead Circuit After a Panel Change
After a panel replacement, a homeowner reports that half the receptacles in the living room and one bedroom are dead, while the lights on the same circuit still work. The electrician finds a 15 A circuit that feeds the lights and receptacles.
632 words, about 3 min