Network Infrastructure Blog

The 2017 edition of the NFPA 70® National Electrical Code® (NEC) contains a new Article 840, Part VI requirement addressing premise powering of communications equipment over communications cable. This requirement only applies when the power supplied is greater than 60W (e.g., it does not apply to IEEE 802.3 Type 1 (15W), Type 2 (30W), and Type 3 (60W) PoE implementations). In this case, the maximum ampacity that may be carried by a cable conductor is determined by the conductor gage (AWG) size, number of 4-pair cables in a bundle, and the mechanical temperature rating of the cable as provided in Table 725.144 of the NEC and excerpted below. Note that this table is based on an ambient temperature of 30° C (86° F).

As an example, the maximum ampacity of one 24 AWG category 5e conductor, mechanically rated to 60° C and contained within a bundle of 62-91 cables, is 400 mA (800 mA per pair). Since the developing IEEE P802.3bt Type 4 90W application is targeting an operating current of 960mA per pair, this example product and installation configuration would not be compliant to the NEC requirements for support of this application. To overcome this restriction, the NEC provides a provision to use a limited power or LP-rated cable jacket to support increased ampacity. Another alternative allowed by the NEC is to use cables having larger diameter conductors and/or a higher temperature rating to reach the desired ampacity capability.

Siemon recommends the use of its shielded category 6A and category 7_A cables (having 23 AWG and 22 AWG sized conductors, respectively) for support of 60W and higher power applications because these cables offer the same application support capability as LP-rated cables with the added benefits of greater heat dissipation, power efficiency, bandwidth, and noise immunity. Note that these cables are mechanically rated to 75° C (167° F) and, according to the NEC table (refer to the cells highlighted in yellow), are suitable for support of at least 500 mA per conductor/ 1 A per pair current levels in bundle configurations of up to 192 cables in 30° C (86° F) ambient temperature environments. Siemon has developed bundling recommendations for a much broader range of ambient temperatures. Following these bundling guidelines ensures that an LP-rated cable is not required to support greater than 60W applications within the environments for which Siemon cables are rated.

Wideband multimode fiber (WBMMF), officially designated as OM5, is a recently released fiber medium that is now recognized within both the Telecommunications Industry Association (TIA) and International Electrotechnical Commission (IEC) standards. OM5 fiber specifies a wider range of wavelengths between 840 and 953nm to support wave division multiplexing (WDM) technology and is fully backwards compatible with existing OM4 fiber specifications.

WDM technology provides the capability to either increase transmission speeds or reduce fiber strand counts by a factor of 4. For example, using standard OM3 or OM4 multimode fiber, 100 gigabit speeds require the use of 8-fibers via 100GBASE-SR4. In contrast, using 25GBASE-SR specifications, 100 gigabit OM5 fiber links could be created using 2-fiber 25 gigabit channels on 4 different wavelengths. Similarly, using 100GBASE-SR4 specifications, 400 gigabit OM5 fiber links could be created using 8-fiber 100 gigabit channels on 4 different wavelengths.

However, it is important to note that there are no applications currently under development within the Institute of Electrical and Electronics Engineers (IEEE) to operate over this medium. In addition, because IEEE typically develops applications based on a significant installed base, it is not certain when and if any application will be developed. Further, OM5 carries a significant cost premium over OM4 and a premium will also apply to any future transmission equipment.

The recent release of IEEE 802.3by-2016 (25GBASE-SR) and the pending IEEE P802.3cd (50GBASE-SR) – anticipated to release in 2018 – demonstrates IEEE’s commitment to the development of higher capacity applications over the installed base of OM3 and OM4 multimode fiber. There is also work on singlemode technologies for short reach (500m) applications via the pending IEEE P802.3cd (100GBASE-DR) and IEEE P802.3bs (200GBASE-DR4/400GBASE-DR4) that may provide a case for singlemode fiber to be considered.

As a result of this pricing premium and application uncertainty, at this time Siemon still recommends deployment of OM3 or OM4 8-fiber MPO/MTP connectivity for seamless migration from current standards-based 2-fiber (10GBASE-SR, 25GBASE-SR) and 8-fiber (40GBASE-SR4, 100GBASE-SR4) applications to future applications.

View our full line of OM3 and OM4 Advanced Fiber Solutions.

Published in 2011, the Construction Products Regulation (CPR) defines the fire performance of all construction products. Under this regulation, all construction products and building materials installed in the European Union (EU) must contain the CE mark that provides proof of compliance.

How Does CPR and the CE Mark Relate to Communications Cable?

As of 10th June 2016, copper and fiber telecommunications cabling is now subject to the CPR with a one year transition period. This means that as of 1st July 2017, all copper and fiber cables supplied to EU member states must comply with the regulation and carry the CE marking. With CPR specifications developed and adopted by EU member states, the regulation facilitates trade between EU member states for any construction products that are intended to be permanently incorporated into a building.

It’s important to note that the CE mark does denote quality—it means that the product meets standards for health, safety and economy of energy. It also only relates to cables intended for permanent installation, which excludes non-fixed cabling infrastructure components such as patch cords and jumpers.

For more background on CPR, visit: Construction Products Regulation (CPR)

 What are Euroclasses?

Under the CPR, existing IEC 60332 flammability ratings will be replaced by different reaction to fire performance known as Euroclasses. There are seven Euroclasses—A, B1, B2, C, D, E, and F—whereby A is the most flame retardant and F is the least. The requirements for the Euroclasses are outlined in the recently published standard EN50575, Power, control and communication cables – Cables for general applications in construction works subject to reaction to fire requirements.

 Who Determines what Euroclass is Required?

EU member states are required to follow CPR and each EU member state will decide which Euroclasses to adopt for their specific construction standards and regulations. Euroclasses B through D are considered low fire hazard cables and must meet EN 50399 Flame Spread testing in addition to EN 60332-1-2 while Euroclass E need only meet EN 60332-1-2 and Euroclass F has no determined performance. Broad use of Euroclass D and E is expected for residential and standard commercial premises throughout the EU.

 How Does the Regulation Impact Cabling Manufacturers?

Any cable manufacturer wishing to sell fiber and copper communications cable into EU is required to test their cables for CPR compliance with a “notified body” required to certify test results. Manufacturers must then draw up a Declaration of Performance (DoP) and affix the CE mark to its cable products and product labels. The purpose of the DoP is to hold manufactures responsible for conforming to the declared specification. As previously noted, all manufacturers supplying copper and fiber cables to EU member states must issue a DoP and affix CE marking to cable by 1st July 2017.

 What is Siemon Doing to Prepare for CPR Compliance?

As a leader in the structured cabling industry, Siemon is currently working with Notified Bodies to test its existing copper and fiber cables and establish Euroclass specifications. We are on schedule to receive Euroclass D and E certification for the bulk of our copper and fiber cables and are targeting to offer CPR compliant product with CE marking by the end of this calendar year. Further communication regarding product availability will be forth coming, and Siemon will continue to monitor all standards, trends and adopted Euroclasses within the EU and adapt cables where necessary.

A Closer Look at Plug and Play MPO/MTP Assemblies

Maybe you’re one of the data center managers that tries to save a little with cheaper fiber assemblies from generic assembly houses. But do you really know if these assemblies are viable for your high speed fiber links?

When it comes to plug and play multi-fiber MPO/MTP cable assemblies used in data center backbone 40 and 100 gigabit fiber links that handle larger sets of complex data from multiple sources, performance is more critical than ever—especially considering the more stringent channel loss requirements of these next generation speeds.

Siemon Labs recently completed comprehensive testing on the performance of plug and play MPO/MTP assemblies, and we can absolutely tell you that not all MPO/MTP assemblies are created equal.

We tested random samples of MPO/MTP and MPO/MTP-to-LC assemblies acquired via standard distribution from four different low-cost assembly houses and from Siemon to TIA and IEC standards for end face geometry, cleanliness, optical performance and mechanical reliability. Each assembly was also tested to Siemon’s specifications which are more stringent to ensure superior performance and application assurance. What did we find?

As detailed in the white paper “A Closer Look at Plug and Play MPO/MTP Assemblies,” the majority of the generic assemblies failed to meet minimum standards requirements across the range of performance-critical parameters. Siemon was the ONLY manufacturer to pass ALL the parameters for ALL tests. In fact, three of the four assembly houses had assemblies that didn’t even offer an insertion loss performance that would allow for the use of a cross connect in a 40 or 100 gigabit channel. And all samples from one of the assembly houses completely failed cable flex mechanical reliability testing with the cable jacket completely pulling out of the rear of the crimp sleeve!

Is this the kind of quality and performance you want to rely on for your high speed data links? Probably not.

Thankfully, Siemon plug and play fiber assemblies are manufactured using the highest quality materials and via rigorous process control over end face geometry, cleanliness and mechanical reliability to ensure superior optical performance. In other words, your high speed fiber transmission can rely on our assemblies.