During the last years, the large hadron collider (LHC), the most powerful particle accelerator in the world, has been running at CERN in Geneva, Switzerland. It includes four large high-energy experiments and the compact muon solenoid (CMS) is one of them. The electronic read-out for the CMS experiment is designed to process signals in the range of $\mu$ A-mA and digitize them synchronously at 40 MHz. Parts of these electronic systems are located inside of a uniform magnetic field of 4 T and operate under particle radiation. These characteristics have forced us to analyze, propose, and conduct electromagnetic compatibility (EMC) tests on the electronic equipment before integrating it into the detector. This paper presents the description and analysis of the first EMC plan and tests that were applied to a high-energy physics experiment before the installation and commissioning of the electronics system.