Issue 142 March - April 2021

Please note: The issue content below is just a summary of the articles in the printed magazine.
The articles are not available on-line. Please refer to the printed magazine for the complete article.
Cable production at full capacity

Twelve months on from the first Covid shutdown, business is booming for cable maker Prysmian. Production at the company’s Auckland manufacturing site is running at full capacity and, with orders coming in daily, it looks like the economic recovery is in full swing.

But while Prysmian is managing this surge in demand, the bigger challenge is overcoming the global disruption to supply chains and getting enough raw materials into the country and on time to make the cable the industry needs.

Prysmian’s national trade manager, Nicola Roberts, says Prysmian is doing everything the company can to ensure reliable cable supply and is urging electrical wholesalers and network contractors to help minimise project disruptions by contacting Prysmian much earlier in the development of a project and advising likely demand.

“We are all in this together and by working together we can make every effort to avoid project delays,” she says, “but the only way we can ensure anything like trouble-free supply is by managing our production schedules weeks ahead of normal planning. The more electrical contractors can forewarn their wholesalers of likely demand as projects are being considered, the better we can meet that demand by securing production time as materials become available,” says Roberts.

“The demand for cable is such that contractors and wholesalers can no longer assume there is plenty of available stock to order from a week or two before they want it. It could be a while before you can dig a trench and expect to pick up cable ex-stock to fill it.”

Prysmian’s general manager, Mark Beckham, confirms lead times have extended dramatically and the company is doing everything it can locally and internationally to meet every order.

Standards stray from the law

Ever since the phasing out of scraping earth plugs in the late 1980s, achieving an effective safety regime for powering both imported and locally-built caravans has never been fully resolved.

In more recent years, risk analysis showed that removing the earth-neutral link would make caravans safer, but MEN supporters argued it would make them more dangerous and certainly so without the retrofitting of an RCD.

To complicate the issue many caravans in use in New Zealand were constructed before any requirement for RCDs was applied, and it is a bedrock principle of regulatory development not to create retrospective requirements. A possible exception to this is where such a rule is essential to public safety.

Also adding to the complication is the way the safety of connectable installations is prescribed in the Electricity (Safety) Regulations and whether the law has been carried through correctly into standards cited by the regulations.

In a recent disciplinary hearing (CE No. 22184) according to the EWRB’s findings, all parties to the proceedings accepted that an RCD installed in an imported caravan had to be a type A and the Board ruled that a warrant of electrical fitness (WoEF) could not be issued if the type AC it was imported with remained installed.

ElectroLink asked an inspector, Ian Turner, of Inspection Services Waikato to identify the provisions in the cited standards that give rise to this interpretation. He says before a WoEF on an imported caravan can be issued, an assessment for compliance with Part 1 of AS/NZS 3000 must be carried out as required by Regulation 78 (2) (c).

Missing the connection

The EWRB disciplinary case against an electrical inspector over a warrant of electrical fitness for a caravan reviewed in the last issue of ElectroLink turned on a key issue: is issuing a warrant prescribed electrical work for the EWRB to rule on.

There has been a lot of discussion on this case and, in a letter on page 8, another inspector has challenged the EWRB’s guilty decision. He contends that the Board and the inspector appearing before it have assumed incorrectly that a Type AC RCD in an imported caravan has to be replaced with a Type A for a valid warrant of electrical fitness (WoEF).

These responses show that while there might a higher level of clarity in the rules than some might think, arriving at a reliable level of clarity requires a detailed knowledge of a library of legislation and standards that have become too complex for a person to reasonably assimilate.

What has also emerged from the Board’s investigation of this case is a picture of a government department and its electrical registration board struggling with the law it is responsible for ruling on and the difficulty its legal advisors have in understanding the terms used in the electricity legislation even before they get to work out how they apply.

In its judgement on case CE No. 22184 the EWRB placed a lot of store in ascertaining definitions of the key terms and then arguing about those definitions. While this approach is helpful for the Board’s lawyers to progress their training on the electricity legislation, it shifts the focus to semantics and away from the regulations relating to the issue that caused the disciplinary hearing.

Why EtherCAT is a fieldbus of choice for industry

Modern industry requires devices to ‘talk’ to one another, that is to exchange data via communication. The number of devices, the amount of data involved and the distances between devices make hardwiring totally impractical. Networking is thus an integral and indispensable feature of today’s automation systems.

Industrial networks fall into two categories: data networks and fieldbuses. Data networks interconnect industrial controllers such as programmable logic controllers (PLCs) to each other (where they can share data), to computer systems (such as databases, SCADA systems and alike), to the Internet and more.

Fieldbus networks gather data from remote devices installed over a wide area on the factory floor, into a central controller. These devices include I/O blocks, motor drives, servos, cameras and more.

Fieldbuses present some unique challenges for network designers. They need to work over cable runs of some distance and, most importantly, must achieve real time performance. Working in real time (also known as ‘determinism’) means the time delay between when a message is sent and received is within a prescribed limit.

Motion control applications, for example, require real time performance in order to be able to synchronise motor movements. Special considerations within the network are needed to achieve this.

Wireless lighting controls are here – why aren’t we using them?

Intelligent wireless lighting controls can be a cost-effective way to save energy, particularly for lighting retrofits.

Some local businesses are already using wireless lighting control systems successfully. However, there is a lot more scope for their use in warehouses, offices, retail and hospitality settings as control cabling is not required, making connectivity much easier.

How does it work?

The Internet of Things (IoT) has allowed wireless control of a wide range of digital devices including LED lamps and luminaires. The luminaire becomes another node on a mesh network that can also include digital sensors, HVAC and security systems, even appliances.

The system works using radio frequency (RF) with a protocol like Casambi or Bluetooth to communicate with a chip near or inside the luminaire. This chip in turn instructs the luminaire control gear. The human interface can be by either smartphone, tablet, or a RF on-wall switch.

In its simplest form the system can switch the luminaire in response to information from a presence sensor or timer, or dim lighting up or down in response to input from a daylight sensor.

The luminaires forward signals to other luminaires across the mesh network, so the control signal needs to reach only one luminaire to control all of them. This means the system will still work if one or more fixtures have failed.

It also allows for installation of wireless controls in areas where the controller would not otherwise be able to communicate with all luminaires because of distance limitations or obstacles to the RF signal. Additionally, this makes retrofit installations clear-cut and separate from existing wired circuits and much easier to specify, procure and project manage.

Lighting design using bollards

Bollards are short posts usually used to separate moving vehicles from people and buildings, but with an added light source, they can also make the surroundings safer and more attractive at night.

When lighting bollards are used in shared pedestrian/vehicle areas like carparks and multi-unit housing developments, they are usually required to provide a light level that meets national lighting standards, obtrusive light restrictions and local council bylaws.

Depending the classification of the site, these standards will dictate the level of illuminance needed on the ground. Most of these areas must also have a certain amount of light on vertical surfaces.

Vertical light will help people identify and assess someone walking towards them, a visual quality that makes people feel safer at night. Vertical light also helps drivers to see people and obstacles that may be in the shared zone.

Bollard lighting on its own is unlikely to meet standards as most modern bollards have little or no upward light component, lighting only up to their own height. They probably won’t give sufficient light at 1.5 metres where the vertical illuminance is measured.

Bollards with upward light distribution are now uncommon because of the drive to reduce light pollution. However, a second light source like a pole-mounted area luminaire can provide the vertical light component.

Shared areas and public paths usually need to meet light uniformity requirements as well. That is, the lighting design needs to avoid creating excessive contrast between areas of light and dark on the path as dark shadows can hide obstacles (like abandoned scooters) and the shadowing can make some people feel apprehensive or unsteady on the path. Once a product is selected, the correct product spacing is needed to provide the required uniformity.