请注意:此版本的所有临时修订版将在您购买时提供。这是适用于吊顶电网低压系统和设备的UL/ULC联合标准UL 2577/ULC-S2577的第一版。只有在引用标准（美国和加拿大）的情况下才存在国家差异。然而，加拿大和美国的标准在技术上是相同的。

Please note: All interim revisions for this edition available at time of your purchase will be included.This is the First Edition of the Joint UL/ULC Standard for Suspended Ceiling Grid Low Voltage Systems and Equipment, UL 2577/ULC-S2577. There are national differences only where standards (U.S. vs. Canadian) are referenced. However, the body of the standard is technically identical for Canada and the U.S.