Canadian Electrical Industry News Week

August 10, 2016

Originally ratified by IEEE in 1999 and 2003 respectively, gigabit Ethernet (1000BASE-T) and power over Ethernet (PoE) are two network technologies that today are considered the norm. With both technologies supported by an estimated 85% of the installed cabling base, they have proliferated in tandem over the past decade to the point where the many enterprise entities are deploying, or planning to deploy, gigabit Ethernet in the horizontal LAN environment and more PoE devices than ever before.

While 10/100BASE-T (i.e., 10 and 100 Mbps) applications required only two cable pairs for transmission, leaving two spare pairs of a four-pair twisted cable available for PoE, gigabit Ethernet requires all four cable pairs for bidirectional transmission. In this scenario, PoE is delivered over pairs that are simultaneously transmitting data.

Often referred to as phantom power and accomplished by applying a common-mode voltage between two pairs in a four-pair Ethernet cable, PoE is intended to not interfere with data transmission. However, DC resistance unbalance in a PoE connection has the potential to cause significant problems. While not required in TIA or IEC performance field testing, resistance unbalance is specified in the IEEE’s PoE standards and making DC resistance unbalance testing a field test requirement will go a long way in ensuring that devices get the power and data they need. As we move towards a new PoE standard in the future, to be known as IEEE 802.3bt and capable of up to 100W, that two pair PoE delivery will move to a four pair PoE delivery. Not only will DC resistance unbalance within a pair be a potential cause of problems, but we will also need to consider pair to pair DC parallel resistance unbalance as another source of potential problems.

Understanding PoE and DC resistance unbalance

The IEEE 802.3af standard for PoE was developed to provide remote low-voltage power to devices over twisted-pair data cabling. Power is injected by power sourcing equipment (PSE), which is typically a PoE-enabled switch or a mid-span power device. The power can be used by a wide range of powered devices (PDs) at the other end, including VoIP phones; wireless access points (WAPs), wall clocks, sensors, cameras, access control panels and more.

The original IEEE 802.3af standard allows for delivering a maximum of 15.4 W (13 W available) of power over two pairs, while the current IEEE 802.3at PoE Plus standard increases the allowed maximum power to 30 W (25.5 W available). The new proposed IEEE 802.3bt PoE Plus Plus standard is designed to provide 100W of power when ratified. PoE Plus was developed in response to more power-hungry devices such as higher power WAPs, pan-tilt-zoom cameras, LED display boards and more. In fact, the latest 802.11ac standard for gigabit Wi-Fi has higher power requirements due to more sophisticated signal processing and a higher frame rate that requires PoE Plus. PoE Plus Plus is being developed to provide power to even more power hungry devices such as multiple radio WAPs, CCTV cameras that also include PTZ and heaters, LED data centre lighting, with many more uses being envisaged.

The IEEE 802.3af and 802.3at standards specify two methods for PSE to provide power using two pairs of a four-pair data cable — Alternative A and B. In Alternative B, power is delivered over spare pairs using Pairs 1 and 4. This is compatible with data signals that only use two pairs (Pairs 2 and 3), including 10/100BASE-T applications. In Alternative A, the power is delivered simultaneously with data over Pairs 2 and 3, which is compatible with both two-pair and four-pair applications, including 10/100BASE-T and 1000BASE-T.

In Alternative A, power is transmitted over the data pairs by applying a common-mode voltage. Power is received and returned using the centre tap of a PD’s transformer, which splits the current between each conductor of the pair. When the resistance of each wire in the pair is equal, the DC resistance unbalance (the difference in resistance between two conductors) is at zero, current is split evenly, and common-mode current is achieved.

With IEEE 802.3bt, we move to a 4 pair based system to deliver the required power. We still have our PSE and PD devices, with the current flow now shared among the four pairs.

While devices can tolerate some DC resistance unbalance, too much unbalance causes the potential for saturation of the transformer. This can ultimately distort the waveform of Ethernet data signals, causing bit errors, retransmits and even non-functioning data links. With a four pair PoE system some DC resistance unbalance between the pairs can be tolerated, but if it is excessive, PoE will stop functioning.

What causes DC resistance unbalance?

DC resistance unbalance within a pair and between pairs can occur in a PoE data link for a variety of reasons. While problems with transformers such as an offset centre tap can occur at both PSE and end devices, DC resistance unbalance is more often caused by poor workmanship, inconsistent terminations and subpar cable quality.

Poor installation practices have long been at the crux of network performance problems. Practices such as ensuring minimum bend radius and maintaining pair twist as close to the point of termination as possible are key to meeting performance parameters, especially in higher frequency applications like 1000BASE-T and 10GBASE-T. While PoE relies more on the DC resistance of a specific length of cable rather than high-frequency transmission characteristics, there are some installation practices that matter.

Consistency in individual conductor terminations is important to preventing DC resistance unbalance. Punching down the individual conductors to the proper IDC tower of a network jack displaces the conductor’s insulation to expose the copper and make the connection.

Ensuring proper and consistent seating during this practice isn’t always easy. A certain amount of force is required to seat the conductors, and inexperience, hand fatigue and larger conductor gauge sizes can all impact the ability to maintain consistency. When two conductors of a pair carrying PoE are terminated inconsistently, DC resistance unbalance can occur. Using the correct termination tool can help increase termination consistency and avoid DC resistance unbalance in PoE systems (see sidebar on termination tools).

Conscientious terminations must also be coupled with precision manufacturing processes as the overall quality of the cable and connectivity can also impact DC resistance unbalance. Manufacturing quality UTP cable requires careful selection of copper conductors and the use of stringent controls to maintain the proper physical geometry of the cable. When a poor quality cable exhibits variations in the diameter, concentricity (roundness), contour and smoothness of the copper conductors, there is a higher risk for DC resistance unbalance in PoE systems.

One of the growing concerns in the industry today is the significant amount of cables containing copper coated aluminum (CCA), copper coated steel and other non-standard conductors masquerading as Category 5e or even Category 6 cables. While these cables can be appealing to those looking for inexpensive networking solutions, CCA cables are not compliant with industry standards and do not support PoE applications due to their increased DC resistance, which can be 55% greater than for a solid copper cable of the same diameter. The greater resistance results in greater heating of the cable and lower voltage available at the powered device.

Unfortunately, testing for DC resistance is not always enough to determine support for PoE as some CCA cables will pass DC loop resistance testing for shorter links. However, regardless of link length, CCA cable will typically feature DC resistance unbalance on pairs due to lack of consistency across conductors (see sidebar on DC loop resistance vs. DC resistance unbalance). It should also be noted that both the ANSI/TIA and ISO/IEC standards require twisted pair data cable to be 100% copper.

Read Part 2: testing for DC resistance unbalance within a pair and between pairs.


This article was originally published online by Fluke: http://www.flukenetworks.com/content/white-paper-dc-resistance-unbalance-testing-easy-low-cost-insurance-your-poe-systems.

 

Contractors! You Deserve Better.

You Deserve BetterContractors! You Deserve Better | Win $2,000 Grand Prize from LEDVANCE, THE WORLD'S LEADING VERTICALLY INTEGRATED LIGHTING COMPANY

OFFERING SYLVANIA AND LEDVANCE BRANDED LIGHTING PRODUCTS IN CANADA


You deserve better and LEDVANCE wants to make sure you know it. Enter for a chance to be one of over 190 winners with the grand prize including $2000 and a SYLVANIA Work Light!

Read More


Changing Scene

  • Prev
E.B. Horsman & Son (EBH) has announced their Victoria branch has moved to a new location as ...
Canada’s Building Trades Unions has been selected as an intermediary for the Apprenticeship Service ...
More skilled trades workers can seek certification in Nova Scotia with changes the Province is ...
Procore Technologies, Inc. has announced it is working with Amazon Web Services (AWS) to ...
The federal governemnt has officially launched a call for proposals (CFP) for the  ...
The Electrical Contractors Association of BC (ECABC) has announced the impending departure of ...
The Minister of Employment, Workforce Development and Disability Inclusion, Carla Qualtrough was at ...
The launch of the Apprenticeship Service stands to help overcome financial barriers employers face ...
The National Electrical Trade Council (NETCO) is pleased to announce that they will be rolling out ...
43 years ago, Steve Silverstein bought a table saw and a delivery van and began a revolution in the ...


Government of CanadaThe federal governemnt has officially launched a call for proposals (CFP) for the Zero-Emission Vehicle Awareness Initiative (ZEVAI). The initiative’s 2022 CFP will help fund new and innovative projects that aim to increase awareness and knowledge of ZEVs and charging and refueling infrastructure thereby increasing public confidence in these vehicles and their economic and environmental benefits.


Natural Resources Canada will provide funding through non-repayable contributions of between 50 and 75 percent of the total eligible project costs, with a maximum funding of up to $300,000 per project. The CFP will close on August 18, 2022.

Read more


 

Omnicable joins ETIMETIM North America announced that OmniCable has joined the product classification standards organization. Headquartered in West Chester, PA, OmniCable has 24 locations throughout North America, and also owns Houston Wire & Cable (HWC). The company partners with many electrical manufacturers and only sells to distributors.

According to John Dean, Director of Marketing & E-Commerce, OmniCable/HWC, “The wire and cable industry is often called commodities, but there are very distinct features and attributes for the different products our manufacturers produce. 

Read More

 


 

Atkore United Poly SystemsAtkore Inc. announced that it has acquired United Poly Systems, a manufacturer of High Density Polyethylene (HDPE) pressure pipe and conduit, primarily serving telecom, water infrastructure, renewables, and energy markets.

“We are pleased to complete the acquisition of United Poly Systems, which strengthens Atkore’s product portfolio, expands our manufacturing capacity and further enables us to meet HDPE customers’ needs,” stated John Pregenzer, President of Atkore’s Electrical business. “HDPE pipe and conduit is a growing market that is expected to benefit from U.S. infrastructure legislation, and United Poly Systems is a great addition to Atkore. We welcome these employees and look forward to working together to continue to serve and support our customers.”

Read More


 

Canadian Electrical Contractor Discussion Group: Can You Count the Deficiencies?

EIN CECD 400Have you ever been called to fix the work of a 'handyman'?

"Was supposedly done by a"certified ' electrician....told the homeowner that he got a $266 permit....no record at TSBC. Can you count the deficiencies?"

"There is a second panel change in the triplex also.......even more deficiencies. Think the guy was a glorified handyman. Ones not obvious: 240 BB heat hooked up 120....drier on 2p20....range on 2p50....water heater fed with 2c14 Bx on 2p15."

Go HERE to join the discussion

 


 

Grimard is more competitive and produces estimates 3X faster with Procore

Procore

When the pandemic lockdowns started in March of 2020, Grimard (an electrical contractor) had to decide whether to shut down its operations entirely or implement a new platform with people who were now freely available for work. Once they implemented Procore, they found a way to efficiently communicate with stakeholders and offer full transparency in terms of project costs and planning. It also allowed Grimard to utilize historical data to make project estimates more accurate. Grimard was able to streamline its bidding process, which made it more attractive to potential clients and helped the business grow.

Read More


 



 

Iron+EarthThe RenuWell Project partners are excited to announce the groundbreaking of two pilot sites located near Taber, Alberta. These pilot sites are the first of their kind to repurpose inactive oil and gas infrastructure as a foundation for renewable energy development and job creation.

When operating, the solar projects will generate 2,030 MWh annually – enough electricity to power 280 average Alberta households or irrigate 11,700 acres of farmland for an average year. This is roughly equivalent to $200,000 in electricity sales per year with 1,100  tCO2e savings in GHG emissions. Over a 25-year lifespan, the projects will generate 50,750 MWh, with GHG emission savings of 28,420 tCO2e.

Read More


 

David O'ReillyBy Elle Bremmer

Recently, I had the pleasure of sitting down with David O’Reilly, Vice President Home & Distribution and Secure Power Divisions with Schneider Electric Canada for a discussion regarding the Wiser EnergyTM smart home solution, the Wiser Approved training program, and his thoughts on several different subjects, including sustainability and future technologies currently in the works at Schneider Electric. David has been with the company for five and a half years in his role.

We recently published a study (version en français ICI) from Schneider Electric showing a strong interest from Canadians in smart home technology. 

Read More


 

Product News

  • Prev
Ericson has launched upgraded versions of their line of Harsh and Hazardous Lighting Solutions. ...
Designed for quick and easy installation, this strong and durable baseboard is easily recognizable ...
The Lithonia Lighting® ESXF LED Floodlight is an all-in-one flood that gives ultimate versatility ...
STARFISH WiFi enabled mobile app controlled. Customize and save various light scenes or utilize the ...
The 8540 Pro profile is designed to disappear into the structure, merging the light source with the ...
Keystone’s DirectDrive DX2 is a UL Type B line voltage tube offering single- or double-ended wiring ...
This voluminous Hubbell® Gangable Device Box offers smooth flat external sides and flush ears that ...
The EarthTronics LED Adjustable Wall Packs has a slim profile design. They can be locked into any ...
Klein Tools introduces new phone Thermal Imagers, one for Android® Devices and one for iOS Devices, ...
The tri-power countertop pop-up receptacle from Hubbell Wiring Device - Kellems® provides power ...


Ericson String LightsEricson announces upgraded versions of their extremely capable line of Industrial String Lights and SL, LED Stringlights. These new and updated products have several key features important when safe, code compliant lighting for industrial workspace is necessary.

Infinitely capable, these ruggedly built products have several industry leading & exclusive features including:

Industrial String Lights:

  • A United States Navy Specification since before WWII, they’re time and application tested...

 

Read More


 

 

Intermatic Pool and Spa SolutionIntermatic Incorporated announced its new P40000 Series Load Centers, a set of next-generation panels for pool-only applications, as well as its new PE24GVA 24-Volt Valve Actuator, an easy-to-install valve actuator that allows for tool-free cam adjustments. Both solutions remove obstacles for pool service professionals while delivering lasting performance.

“Intermatic load centers and valve actuators have been the preferred choice of pool professionals for more than 30 years,” says Brian Lamberty, product marketing manager at Intermatic. “The PE24GVA and P40000 Series build on that tradition, helping pool professionals streamline service calls while setting the standard for quality and performance.”

Read More


 

 

Klein Tools Zipper BagsKlein Tools introduces new Stand-up Zipper Bags, in a 2-Pack with 7-Inch and 14-Inch sizes, both designed to handle tough jobsite conditions and stand up so tools and small parts can be easily accessed when working.

Stand-up Zipper Bags, 7-Inch and 14-Inch, 2-Pack (Cat. No. 55559)

  • Perfect for storing pliers, wrenches, screwdrivers, drill bits and other small tools and parts
  • 4 1/2’’ tall zipper bags come in two sizes:
    • 14’’ (36.6 cm) dark gray
    • 7’’ (17.8 cm) royal blue


Read More


 

Emerson HV SafetyThe Occupational Safety and Health Administration (OSHA) estimates 350 employees are killed annually in electrocution accidents, which roughly equals one fatality per day. In the face of these dangers, OSHA officials and industry safety consultants alike recommend eliminating potential hazards on work sites, rather than simply relying on contractors or employees to follow safety guidelines.

To help safeguard employees from electrocution, Emerson has launched its Appleton™ Powertite™ Lock Collar, a device that fastens over plug and connector connections and is secured with a padlock, preventing unauthorized personal from disconnecting the cable connection once in place. 

Read More


 

Peers & Profiles

  • Prev
Watt’s the Word is a recently launched Electrical Industry Podcast hosted by Zack Hartle and ...
Allana Kellett-Jamieson loves working in the electrical sector and is proud of the great focus ...
As the head of ABB Canada's electrification business unit, Éric Deschênes is no newcomer to the ...
Karen Pullen knows what it’s like to be the only woman on a construction site, and as a proud ...
As of February 2021, Martin Stephenson is the new President and CEO of Signify Canada.   ...
This past July, Kerith Richards, who has worked for Service Wire Company for the last seven years, ...
EngWorks was formed in 2004 as an electrical engineering and consulting firm by Allan Bozek, “After ...
Headquartered in Concord, Ontario, Mercury Lighting services national retail, ...
Among the recipients of the 2021 Clean50 Awards announced last month is Carolina Gallo, Vice ...
Sarah Silverstein is a principal with Liteline along side her two brothers Mark and Daniel. ...

Copper $US Dollar price per pound

Kerrwil Publications Great Place to Work. Certified December 2019 - December 2020

538 Elizabeth Street, Midland,Ontario, Canada L4R2A3 +1 705 527 7666
©2022 All rights reserved

Use of this Site constitutes acceptance of our Privacy Policy (effective 1.1.2016)
The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of Kerrwil