To work as a licensed journeyman plumber in Los Angeles County, you must obtain a journeyman plumber certification from the Department of Public Works Building and Safety Division. Status as a journeyman plumber authorizes you to install, alter and repair plumbing under the employment of a licensed contractor in Los Angeles County. To obtain journeyman plumber certification, you must have at least four years of verifiable on-the-job plumbing experience, and you must pass a certification examination.

Obtain documentation proving that you have four years of experience working under a licensed plumbing contractor in Los Angeles County or elsewhere. Testimonial letters from former employers must be written on company letterhead, must include the contractor’s state license number and must be notarized. If you hold a contractor’s license yourself, your official license documents would suffice as long as they show the required experience. You can use completion of an apprenticeship program as experience as long as you submit a testimonial letter meeting the requirements described above. Take these documents with you to your examination.

Download and print an Application for Examination and Registration from the Los Angeles Department of Public Works website (see Resources). Complete the form and submit it, along with the appropriate fee, to the indicated address. After processing, you will receive an exam notification in the mail, including the exam date, location and associated instructions. Read this document carefully. An example of this notification is available on the Department of Public Works website (see Resources).

Collect the materials required in your exam notification, including your proof of experience documents, picture identification and a copy of the 2006 Uniform Plumbing Code. Look for the plumbing code book at most large bookstores or online.

Take your exam on the appointed date. The exam is based on the plumbing code book, which you will be able to reference in the exam room. Your success on the exam will depend on your working knowledge of the code and your ability to quickly reference the code for purposes of completing exam questions. To pass, you must achieve a score greater than 70 percent.