This part of IEC 61334 applies to electrical equipment to be used in distribution line carrier (DLC) systems on both medium-voltage (MV) and low-voltage (LV) distribution networks. It specifies the requirements (frequency bands, output levels, spurious emissions, etc.) for MV and LV distribution networks respectively. It specifies disturbance limits in the frequency range from 3 kHz up to 30 MHz. The upper frequency limit has been fixed at 30 MHz according to the CISPR recommendations for conducted disturbances. It does not specify the signal modulation methods nor the coding methods nor functional features. Environmental requirements and tests are not included. NOTE – In most countries the transmission is subject to regulation. Compliance with this standard does not imply permission to establish communication on a public supply network, between public supply networks and consumer installations, or between consumer installations where this would not otherwise be allowed. The object of this standard is to limit mutual influence between signal transmission equipment in electrical installations and between such equipment and other equipment. In addition, this standard is intended to limit interference caused by signal transmission equipment to sensitive electronic equipment. In some cases, interference caused by other electrical equipment may lead to misoperation of the mains signalling equipment. Guidance on proper use and warning of improper use are included in the installation and operating instructions supplied with each item of equipment. Where appropriate, a notice is attached securely to each product giving the substance of the following warning: Mains signalling must not be used to control equipment that could become a hazard to people or property if it inadvertently operates or fails to operate in any way.