DC Plumber study guide
DC Plumber · Work through your exam, one topic at a time.
The District of Columbia Plumber License Examination is the assessment used by the DC Board of Industrial Trades, under the Department of Licensing and Consumer Protection (DLCP), to decide whether an applicant is qualified to hold a plumbing license in the District. It serves apprentices moving up to journeyman status, experienced plumbers relocating from other jurisdictions, and master-level candidates who intend to contract, supervise, and pull permits. The DC Plumber study guide has 8 sections and about 3,284 words.
01Plumbing Code and Regulations: How the District's Code Is Built and Applied
The code domain tests whether you can find the rule that governs a job in the District and apply it in the right order. DC enforces plumbing requirements through Title 12A of the District of Columbia Municipal Regulations (the Construction Codes).
439 words, about 2 min02General Plumbing Knowledge, Materials, and Fixtures
Copper: Type K for buried service, Type L for general distribution, Type M for above-ground dry locations. Joints by lead-free solder, brazing, or listed press fittings.
396 words, about 2 min03Water Supply and Distribution Systems
Minimum 8 psi residual at the fixture under flow; maximum 80 psi static. Above 80 psi a pressure-reducing valve is required, with a strainer, access, and a thermal expansion tank downstream, because the PRV creates a closed system.
377 words, about 2 min04Drainage, Waste, and Vent Systems
Slope is 1/4 in per ft for pipe 2 1/2 in and smaller and 1/8 in per ft for 3 in and larger. Sizing uses drainage fixture units (DFU) from the code table, accumulated along the run, then converted to pipe size for the building drain, building sewer, and branches.
448 words, about 2 min05Fixtures, Fixture Fittings, and Water Heaters
A water closet needs about 15 in from centerline to a side wall and 30 in of clear width, with working space in front. Accessible fixtures follow ICC A117.1: clear floor space, insulated or protected supply and drain pipes under lavatories, and lever handles.
412 words, about 2 min06Fuel Gas Piping and Gas-Fired Appliances
The District adopts the International Fuel Gas Code with amendments; the gas chapter governs materials, sizing, installation, and testing. Acceptable materials include black steel pipe, corrugated stainless steel tubing (CSST), and copper where the code permits it.
393 words, about 2 min07Backflow Prevention, Cross-Connection Control, and Potable Water Protection
Backsiphonage is caused by negative pressure in the supply; backpressure is caused by downstream pressure higher than the supply. The device must match the mechanism as well as the hazard.
417 words, about 2 min08Safety, Tools, and Job-Site Practices
Excavations: a protective system is required at 5 ft depth; a competent person inspects daily; spoil and materials stay at least 2 ft back from the edge; a ladder is provided within 25 ft of travel. Confined spaces: permit-required spaces such as vaults, pits, and large tanks need atmospheric testing before entry, an attendant, and rescue provisions.
402 words, about 2 min