UL 1863 Another relevant standard is UL 1863, Standard for Communications-Circuit Accessories , which includes tests for impact, crushing, flexing, and pulling. UL 1863 requires a UL 94 flammability classification, stating that components using plastic materials to enclose or support current-carrying parts must have a flame class of V-0. It is important to note that UL 1863 certification testing can use a dielectric withstand voltage of either 500 root mean square voltage (V RMS) or 1000 V RMS. Connectivity tested to 500 V RMS can only safely support PoE voltage levels up to 42.4 V DC, while connectivity tested to 1000 V RMS can support voltage levels up to 353 V DC. Since many PoE-enabled devices like wireless access points, light-emitting diode (LED) lights, and digital displays require more than 42.4 V DC, testing to 1000 V RMS is crucial. This higher rating ensures support for all PoE-enabled devices. Unfortunately, manufacturers with RJ45 connectors listed to UL 1863 may not necessarily specify the level of testing, so it is essential to choose products verified for PoE applications. UL 2043 UL 2043, Standard for Fire Test for Heat and Visible Smoke Release for Discrete Products Installed in Air- Handling Spaces , is a critical safety standard required by the National Electric Code ® (NEC ® ) and enforced by local building codes and authorities having jurisdiction. Commonly referred to as "plenum-rated," UL 2043 is required for components used in plenum spaces, which pose a higher fire risk due to air circulation. RJ45 connectivity deployed in the plenum space must be plenum-rated to protect property and lives. Unfortunately, many commodity patch cords on the market are not plenum-rated, primarily because the cable used in the patch cord is not plenum-rated. When using patch cords in the ceiling space, it is essential to verify that the entire patch cord complies with UL 2043, including the cable and the RJ45 plugs on either end.
low risk not making contact, while those set too high can cause increased wear on the contacts, and in extreme cases, deformation of the jack contacts. Out-of-specification jack contact angles are also problematic: an angle that is too steep can reduce the contact area, while one that is too shallow can interfere with the plug housing. • Latch Geometry : The plug’s latch geometry is critical for ensuring the correct contact position. Insufficient latch height or depth can prevent the locking mechanism from functioning correctly, leading to electrical discontinuity if manipulated. A latch that is too high or too deep can make plug removal difficult, causing user frustration and potentially deforming the latch.
RJ45 connectors that do not comply with TIA-1096-A are prone to increased resistance, oxidation, and poor plug-jack alignment. In PoE applications, these issues contribute to the formation of hot spots. In extreme cases, these hot spots can cause thermal runaway, an uncontrolled chain reaction of escalating heat generation and temperature. This can push temperatures beyond the maximum operating limits, potentially causing connectors to melt, damaging network equipment, or even initiating a fire. A significant concern for all RJ45 connectors is the removal of plugs while under PoE load, which can produce an arc within the discharge area (Figure 4). This arc erodes the gold-plated contact surface, and corrosion migrates across the entire contact over time. Continuous unmating under PoE load can eventually cause plug and jack contacts to weld together. Reinserting a plug with corroded contacts can also cause the corrosion inside the jack to slough off, further degrading performance. The design of modern RJ45 connectors should prevent arcing from occurring within the nominal contact area, as corrosion in this area can lead to poor network performance, increased bit error rates, and even nonfunctional links (Figure 5). While no standard currently defines plug removal under PoE load, IEC 60512-99-002, Connectors for Electrical and Electronic Equipment, Tests and Measurements , provides testing guidance to ensure reliability when unmating under PoE load. The latest
revision of IEC 60512-99-002 (Edition 2.1 2025-04) specifies that mated connections cannot exceed a resistance change of 20 m Ω after being subjected to 100 insertion and removal cycles under a load condition of 55 V DC and 2000 mA applied to each conductor. RELEVANT UL STANDARDS: PROTECTING PEOPLE AND PROPERTY RJ45 connectors are also subject to various UL standards, as established by the global safety science leader UL Solutions. These include standards related to smoke density, flammability, and flame propagation. UL 94 A primary safety standard for RJ45s is related to the flammability of plastic materials used for plug and jack housing. UL 94, the Standard for Safety of Flammability of Plastic Materials for Parts in Devices and Appliances , tests the flammability of plastics, with V-0, V-1, and V-2 vertical burn ratings that indicate the material's ability to extinguish a flame after ignition. Of these three classifications, V-2 is the most relaxed, while V-0 is the most stringent. RJ45s that only meet V-1 or V-2 ratings are non- compliant and at an elevated risk of contributing to the spread of flames in the event of a fire. This is especially a concern in PoE applications. When hot spots result in thermal runaway, UL 94V-0 materials play a crucial role in preventing the spread of flames (Figure 6).
AN UNFORESEEN HAZARD: THE PERILS OF MODERN POE TECHNOLOGY
RJ45 connectors were not initially designed for power delivery. However, since the introduction of PoE in 2003, the amount of power delivered along with data has significantly increased: • IEEE802.3af (2003): Type 1 PoE, delivering a maximum of 15.4 W over 2 pairs (up to 13 W at the device). • IEEE802.3at (2009): Type 2 PoE, delivering a maximum of 30 W of power over 2 pairs (up to 25.5 W at the device). • IEEE 802.3bt (2018): Type 3 PoE, delivering a maximum of 60 W over 4 pairs (up to 51 W at the device), and Type 4 PoE, delivering a maximum of 90 W over 4 pairs (up to 71.3 W at the device).
FIGURE 6 : RJ45 plug showing the results of thermal runaway on Pins 7 and 8 caused by a non-compliant RJ45 jack. The use of UL 94V-0 materials allowed the plugs to self-extinguish, whereas materials of a lesser flame rating could have resulted in catastrophic flame spread. Source: Sentinel Connector Systems
FIGURE 4 : Unmating under PoE load causes an arc at the discharge area that can damage the plug and jack contacts. Source: Leviton
FIGURE 5 : RJ45 connectors must ensure that damage from arcing remains in the discharge area and does not occur in the nominal contact area. Source: CCCA
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