New energy classifications
Murray Teale explains how changes to the long-standing information and communication equipment safety standard will see the emergence of new energy classifications.
While the industry awaits the ratification of 100W power over Ethernet on generic cabling, changes to AS/NZS 60950.1:2015 Information technology equipment – Safety General requirements, which deals with the delivery of DC power for telecommunication equipment, sees the emergence of new energy classifications.
These new energy classifications will see power exceeding 100W being delivered over telecommunication cabling with commercially available products that are now available, delivering digital power of 1,000W at 2,000m over a single pair.
The delivery of remote powering at this level creates a number of changes to industry, standards and regulations as changes create new challenges to both safety and performance.
New Energy Source Classification
The new published AS/NZS 62368.1:2018 Audio/video, information and communication technology equipment in broad terms addresses three energy classes, – ES1, ES2 and ES3.
These energy sources may be used on telecommunication cabling for remote powering.
Along with the energy source classification, the standard also defined different types of people – put simply
- Ordinary person
- Not skilled or instructed
- Instructed person
- Instructed or supervised by a skilled person
- Who can responsibly utilise safety equipment and procedures for the associated energy source
- Skilled person
- Relevant education, qualification and/or experience to identify hazards and take appropriate actions to reduce the risks to them and others
Along with Energy Source (ES) and ‘type of people’ classifications, the standards also address safeguards including but not limited to, basic safeguards, equipment safeguards, installation safeguards, skilled safeguards and supplemental safeguards.
The basic concept is to ensure that adequate safeguards are put in place. The safeguards will be specific safeguards to protect specific types of people from specific energy sources.
For the different energy sources, the following would appear to hold true:
- ES1 classification is when either the touch current limit or the touch voltage limit is considered safe for an ordinary person to touch.
- ES2 classification is applicable when ES1 conditions have not been met, however is still either touch current limited or touch voltage limited but is a higher level than ES1.
- ES2 is considered to be safe with basic safeguards.
- 100W Power over Ethernet (PoE) and HBase T would be considered to fall under ES2 classification.
- ES3 classification is applicable when ES2 conditions have not been met.
- ES3 circuits have no voltage and no circuit current limit.
- ES3 is classified as hazardous and requires basic and supplemental safeguards to protect ordinary persons.
What are the implications of remote powering?
Remote powering on telecommunication cabling has two primary areas of concern that need to be addressed by standards.
Potential contact with a hazardous energy source and heat rise within cabling causing fire or cable failure.
While LV telecommunications (ES3) cabling has been within AS/CA S009:2013 Installation for customer cabling (Wiring rules) for some time, its application has been typically limited to special applications like EWIS and public address systems; the new energy classification may well see ES3 run over generic or structured cable like systems.
The use of ES3 circuits on generic and structured cabling systems will have to adequately address safety issues and ensure that adequate safeguards are in place to help ensure the safety of the person working on or using telecommunication cabling. This requirement may well require cable providers to have the ability to identity ES3 cable and equipment, and ensure appropriate safeguards are in place.
The heat rise in telecommunications will be affected by ES2 and ES3 circuits as a result of higher current flow. Generic and structured cabling has the challenge that what is put on the cabling system is not controlled by the cable provider. With the ongoing deployment of Internet of things (IoT) technologies using remote powering and the introduction of ES2 and potentially ES3 running over generic cabling, a number of challenges present themselves related to heat rise.
(AS) ISO/IEC TS 29125 Information technology – Telecommunications cabling requirements for remote powering of terminal equipment looks at the issue of heat rise in cable bundles with 500mA per conductor 1,000mA per pair (ES2).
AS/NZS 62368.1 has no limit on current and ISO/IEC 11801:2017 Information technology – Generic cabling for customer premises has channel requirements to 750mA per conductor, which exceeds the work undertaken by ISO/IEC TS 29125. As such ISO/IEC TS 29125 can only really be used as a guide to the effect of powering telecommunication cabling.
ISO/IEC TS 29125 indicates a number of factors effecting heat rise in a cable bundle including the following
- Conductor size
- How many pairs are energised
- Current in each pair
- Cable construction
- Ambient temperature
- Installation conductions such as open air, on tray in ducts, sealed conduit within insulation
- DC resistance unbalance
The challenges for standards in Australia is:
- The suitability of a telecommunication cabling system is dependent on the installation, cable selection and how much power is carried within the cable/cable bundle.
- An IoT device requires both communication and power and twisted pair cabling provides both.
- The adoption of 100W PoE is likely to see higher levels of power used more often
- That the regulatory model does not address who connects services on a generic/structured cabling system.
- It is possible that enough power can be injected into a cable bundle meeting AS/CA S009, AS/NZS 3080 and ISO/IEC 11801 by the connection of approved active equipment to render the cabling non-operational.
- The revised AS/CA S009 currently under development will need to address heat rise, however this standard does not address what services are activated over structured or generic cabling by the end users.
The challenges for industry are
- The concept of service activation by end users may well affect the installed cabling operation, which will have an associated impact on systems supporting safety, security and operational reliability that use twisted pair cabling.
- Cable providers will need to understand the new energy sources classification and how they will be applied within the regulatory framework.
- The rapid ongoing development and deployment of IoT may well see standards lagging technology and the convergence of technologies may see emerging technologies fall outside traditional standards and regulatory framework. As such, the Duty of Care obligations for individuals and organisations may need to be more carefully considered than in the past.