Test.com has two free electrician exam practice tests that use questions that are similar to the ones in the actual licensing exam. The first practice test is for journeymen and the second is for master electricians. Test.com scores the practice exams and provides explanations for the answers.
For more practice, JadeLearning.com offers 600 questions, as well as 17 learning modules that are specific to the electrician exam, with a 30-day subscription to the website. ElectricianPracticeTests.com also offers several practice tests for free with detailed explanations for correct answers. NECQuestions.com also has learning packages for electrician exams, each with different access to practice questions depending on the price.