Power-over-Ethernet or PoE is one of the more exciting electrical technologies today, but the heightened electrical load means Standards must adapt and change. Sean Carroll writes.

PoE is data and power over a single twisted pair cable, either Category 5e, 6 or 6A. It lets network cables carry electrical power, cutting down the number of connections required. PoE brings several advantages to residential and commercial installations, including time and cost savings, flexibility, safety, reliability and scalability.

But despite the benefits of using PoE, combining both cables has led to more power being sent through fewer solutions, and the associated standards look like they also need an upgrade.

“With the increased use of PoE and as business clients try to reduce cost factors, there is a level of difficulty that clients will face in understanding the risks to buildings from heat rise, arcing and electrical shock safety for their workers and for the industry,” Australian Digital and Telecommunication Industry Association (ADITA) secretary Dominic Schipano writes.

Dominic has written on the topic for the ADITA in the past. He adds that there are technical reviews in light of the PoE demands on the Internet of Things and 5G, but any changes to technical standards now being drafted could remove some limits on current and voltage, exposing telecommunications workers, and possibly even users, to the risks of heating and underperformance.

As of July 2020, a proposal to change AS/NZS 3835 Earth potential rise – protection of telecommunications network users, personnel and plant was submitted to Standards Australia. It highlights the fact that this Standard hasn’t changed in 15 years and, even before adding in PoE, needed to be revised.

Given how much the telecommunications industry has changed since this Standard’s last revision, the industry needs to review how incoming technologies like PoE, NBN and networked substations, among others, have impacted the electrical industry. Additionally, are these technologies providing optimised safety environments for telecommunications personnel?

A proposed change to AS/NZS 3835 has been put forth and this article will run over some of the alterations. Some of the suggested changes are run-of-the-mill updates when changing a Standard, this one includes compliance with SG-006 Rules for the structure and drafting of Australian Standards, making use of AS/NZS 62368.1 definitions of “instructed”, “ordinary” and “skilled” as well as removing the carrier centricity and make the revised AS/NZS 3835 telecommunications-user centric.

The meat of the suggested changes is focused on identifying and minimising Earth potential rise (EPR) hazards for life safety.

The net benefit is an improved identification of, and treatments to manage and minimise EPR hazards to both life, safety and equipment. An EPR event may expose personnel, users and structures to hazardous voltages. By revising this standard, the likelihood of related injuries from EPR hazards such as electric shock will be significantly decreased.

Updates to the 3835 Standards will ensure telecommunication personnel are working in safe environments and the safety of people near active work sites will be accounted for. Revisions of the standard will ensure the safety of technical personnel through up-to-date specifications that take into account new equipment and technology, providing measurable assurance benefits for the telecommunication personnel community.

Specific revisions to AS/NZS 3835 that have been suggested include:

• AS/NZS 3835.1 Section 4: Voltage limits – confirm Australian/New Zealand voltage limits and telecom facility location treatments.
• AS/NZS 3835.2.3.2: EPR hazard situations – check all situations for currency, and for the application of ‘modern’ techniques.
• AS/NZS 3835.2 Section 7: Review sections with ‘requirements’ to ensure the scope of mitigations doesn’t include conduit, that 7.4 aligns with AS/NZS 1768 and validate telecom facility mitigation techniques in 7.4 with current practices.

Many of the other suggestions focus on keeping the Standard current, focusing on updating graphs, examples and electrical limits to ensure workers have the appropriate protection.

As for the environmental impact of the revised Standards, electric faults and EPR events have the potential to cause fires. Through an update, the likelihood of a fire and consequent environmental degradation is significantly reduced.

As Dominic mentioned in a 2018 article when PoE was entering the industry: “Business clients are usually more interested in cost factors – and that it works – than in technical details and very few will be technically minded anyway, so will often be unaware of the risks involved, particularly when using older, existing cable never intended for the higher power transfer with PoE.

“Legacy telecommunications building cabling usually has not been rated for the proposed power changes to PoE standards. In short, you could use what is known as Category 5 which in the past was fit for purpose, but future overload can be an issue. With modern cable known as Category 6 and 6A, in broad terms, the difference is cable diameter, so 6A can carry more current, therefore the wattage rating is higher but still safe. It should become common practice that customers are advised of the wattage capability of whatever is installed -existing Category 5, 6, 6A or higher – so any additional items connected over time have their power load factored in.”

For economic impacts, telecommunication network equipment will reflect up-to-date industry needs and safety specifications, ensuring related products on the market are subject to fair competition. The Standard will help support an even playing field of high-quality and safe telecommunications equipment.

The cost savings for updating the 15-year-old Standard come through in damages. It’s not as if new technology is cheaper or easier to protect, but fewer accidents and appropriate protections for workers means less damage.

As Dominic and the ADITA wrote when PoE was entering the telecommunications industry, now is not the time to water down technical standards. A revision of AS/NZS 3835 is not only essential because of its age, but because of technological advances.

It’s the role of the Standards to guide electrical workers safely through their day-to-day jobs. An update to the Earth potential rise guidelines will do this.