Kele’s UL Panel Shop: Your Source for Meeting Code

Did you know that when you assemble power supplies, controllers, relays, transmitters, and all that other stuff into an enclosure for your control panel, there’s a rule in the NEC that requires your panel to be listed and labeled as an industrial control panel?

Article 409 of the NEC is devoted to the installation of industrial control panels, which are defined as an assembly of two or more components consisting of:

  1. Power circuit components only, such as motor controllers, overload relays, fused disconnect switches, and circuit breakers;
  2. Control circuit components only, such as pushbuttons, pilot lights, selector switches, timers, switches, control relays; or,
  3. A combination of power and control circuit components.

Articles 100 and 110 of the NEC further insist on listed and labeled equipment where such safety standard exists. An informational note in Article 409 refers the installer to UL 508A as an example of a suitable safety standard for industrial control panels. Kele’s UL 508A panel shop can fulfill your needs for a listed and labeled industrial control panel. Send us those drawings in whatever format you choose, and we can help make your panel conform.

So what is UL 508A all about? It’s all about safety – safety from fire, and safety from personal injury. The standard stipulates everything from enclosure type to wire size. There’s a lengthy part about proper separation of power circuits from Class 2 circuits. There are standards that must be met for every part installed in the panel that is upstream of Class 2 circuits. There are labeling requirements for many different scenarios. There are requirements for overcurrent protection and short circuit protection. In sum, a UL 508A panel is a safe panel.

Why Kele? Our UL Panel shop is authorized by UL to list and label your panel as meeting UL 508A standards. Our staff is regularly trained, and a UL inspector makes sure that our work is up to snuff.

We have recently added an additional 1,800 square feet to our panel shop, for a total of 6,720 square feet.

This means we have the capacity to handle your largest projects.

See below for some pictures. We currently have 23 people on our Panel Team with over 150 years on combined experience in BAS/panel building. We’ve also added a new Panel Review Team that will inspect all panel drawings before the panels are moved into production to eliminate any issues or questions plus a Panel Shop Manager, Lisa Bennett, who will make sure your panel is built to spec, on-time and tested before it ships to you, ready to install.

Call Bennie Crowder today at 888-397-5353 or email us at to get your control panel UL listed. We’ll build it up to the standard, test it, and ship it to you ready to install. Our normal lead time for building panels is 2 weeks or less plus there is an expediting option for quicker shipment.  For more information on our panel shop, please visit

Repeat / NSTA Panel Assembly Area

Custom Panel Assembly Area

Inspection / Pack Out Area

Controls and Cables in Environmental Air Handling Spaces, Ducts, and Chases

First, let’s discuss controls and their enclosures in air handling spaces, ducts, and plenums. Many times, we have to install items in these spaces and it’s important to consider that anything we put in there should either be non-combustible (metal) or else be listed under UL 2043 for use in air handling spaces.

The NEC is what governs this requirement.  Section 300.22(C)(3) states that, “Electrical equipment with a metal enclosure, or electrical equipment with a nonmetallic enclosure listed for use within an air handling space and having adequate fire-resistant and low-smoke-producing characteristics, and associated wiring material suitable for the ambient temperature shall be permitted to be installed in such other space unless prohibited elsewhere in the code.” An informational note included in the code defines UL 2043 as a permissible standard for such a nonmetallic product.

Not many plastic items meet this requirement, so it’s best to stick with metallic enclosures. The purpose behind this limitation is that we don’t want smoke to spread via the air handling systems in the event of a fire – and we certainly don’t want that smoke to originate inside the air handling system.

UL 2043’s title is Fire Test for Heat and Visible Smoke Release for Discrete Products and Their Accessories Installed in Air-Handling Spaces. Anything combustible (that is, not metal) installed in an air handling space should be listed to this UL standard. Confusion comes in when products have been listed to other flame test standards.  A product listed as flame-spread tested to UL 94 V-0 or UL 94 H-2 is NOT the same as UL 2043, and does NOT indicate that the product is suitable for use in air handling spaces. Some inspectors will accept these flame-spread ratings, but of late that number of inspectors is dwindling. They want to see “Plenum Rated” and UL 2043 is the only standard available at this time to apply such a label. UL 94 is a test for flammability only. Smoke is the key to safety in air handling spaces.

So what’s the do-all solution?  Use a metal product, or put your plastic product in a metal box.  It’ll never be questioned by an inspector.  Temperature sensors like the Kele KT-D and Precon ST-D are all available with metallic wiring boxes (XH or XW options).  Humidity sensors like the KH-D and HD-20K have metal wiring boxes as well.  Stick with these when in-duct or in-plenum mounting is essential.  Of course, if in-duct or in-plenum mounting is not essential, don’t mount it in there!

Now let’s have a look at wiring in air handling spaces and chases. If not in metal conduit, there is a wide range of choices for low-voltage cabling – plenum and chase ratings have been around much longer than UL 2043, so manufacturers have made listed cables for every application. The important thing to take away from this article is that there are two very different ratings available.  Plenum rating is one, and chase (riser) rating is another.  Be certain that your cable is marked and listed for use in plenums and/or risers as appropriate. Substitutions may be made according to Table 725.154(G) in the NEC.  In general, plenum rated cables can be used in risers, but not the other way around.  Kele’s Model CBL carries both CL3R and CLP3 ratings and thus can be substituted for almost any application.  Here’s a copy of Table 725.154(G), courtesy of the National Fire Protection Association. It illustrates the hierarchy of Class 2 and Class 3 cable types allowed in various spaces:


  • CL3P = Class 3 Plenum
  • CL2P = Class 2 Plenum
  • CL2R = Class 2 Riser
  • CL3R = Class 3 Riser
  • PLTC = Power Limited Tray Cable
  • CL2X = Class 2 Limited Use
  • CL3X = Class 3 Limited Use
  • CL2   = Class 2 General Purpose
  • CL3   = Class 3 General Purpose

Remember, as professionals in the building automation industry we are a part of the team that is charged with preventing the spread of fire and smoke in buildings. By paying attention to what we install in plenums, ducts, and riser chases, we can insure the safety of those who inhabit our buildings.

Green Buildings need Clean Electrical Power for Sustainability

Major changes are taking place in the United States as we all move forward to reduced energy consumption and utilization of renewable energy sources in our homes, offices, campus environments, and factories.

As new technology becomes available with ever increasing returns on investment many owners are ready to become part of the “Green Movement” that is currently taking place all across america. No question about it the time is right for all us to move forward with our Green initiatives.

With this in mind it is important to understand the goal here is to save money across all of our operating budgets. The two basic tenets of a green operation are energy efficiency and sustainability. In order for a building, process or product to be truly “green” it must achieve both of these goals.

There are many products and services available today that can dramatically reduce our consumption, improve our efficiencies, and supplement our energy sources. These new technologies VFDs, LED lighting, Building automation Systems, Solar generation, Battery Storage, to name a few all have one thing in common, they affect the the power distribution in our building in many ways. Many times it is a combination of these building changes that begin to interact with each other.

For example, having re-lamped an entire garage with LED lighting retrofits a hospital was pleased with the energy savings they were enjoying until they had failures of the lights due to to power quality issues in the building during generator operations. All of the energy savings were lost due to the cost of replacement electronics.

Sustainability of the equipment in our buildings is highly dependent on the Power Quality within our buildings. Many repairs or glitches within our systems can be traced back to power quality issues when adequate Power Quality Monitoring is done.

In the past it has been an expensive time consuming effort to have power quality surveys done in the buildings. Most cases these were done after the fact when problems had already caused major disruptions and equipment failures. This reactive method of understanding the Power Quality Dynamics of our building may have gotten us by years ago, but with all of the new changes taking place a more proactive real time Power Quality Monitoring Solution is needed.

The ability to install powerful “Real Time” Power Quality Meters with alarming functions and data collection is now highly cost effective and key to maintaining sustainability of our buildings. These PQUBE Power Quality meters are like the Black box recorder on an aircraft. They sit within the electrical cabinets and switchgear monitoring Power Quality 24/7 in real time.

Once an event is detected they generate alarms and reports as to what the event was, how long it lasted and most important they identify their location which is critical in understanding our buildings operations.

Taking only 30 min to install, and no software to learn the PQubes are the most cost effective and useable Power Quality Meters to date. Their small footprint (about the size of your hand) allow them to be retrofitted into existing electrical panels, transfer switches, and switchboards at many locations within your building.

As we make these major investments in green technologies it only makes sense that we know our buildings Power Quality, real time, all the time. PQube Power Quality meters put you ahead of problems before they become disasters.

THE (RS-485 Network) TERMINATOR Or The Dance of the Data Pulses

If you’re involved with building automation systems you know (unless you’ve been living under a rock like the guy in that insurance commercial) that the modern trend is to connect all your building controls together on networks. Networks make it easy to add or move control nodes as your building control needs change since the nodes all connect to the network in a consistent, simple manner.

Obviously the various monitoring and control nodes on a building automation network must be able to talk to each other over some sort of medium. Both wired and wireless networks (or a hybrid combination of the two) are possible. Almost all wired networks deployed for building automation use twisted-pair communications cables. There are three popular types of twisted-pair communication schemes in use:

RS-485 (BACnet MSTP, Modbus RTU, Metasys N2 protocols)
FT-10 Free Topology  (Lontalk protocol)
Ethernet (BACnet IP, Modbus TCP protocols)


Today we are going to discuss the RS-485 twisted pair communications scheme and the significance of a little component called the “network termination resistor.”

A twisted-pair communications cable, as the name implies, has two insulated signal conductors twisted around and around each other at a consistent (N turns per inch) twist rate. Twisting the insulated conductors around each other reduces noise radiating outward and also improves immunity to external noise pickup. Twisted pairs are especially beneficial when used with a certain type of transmitter and receiver hardware known as “differential” signaling hardware which is used in RS-485 communications.

Twisted-pair communications cables have an electrical property called “characteristic impedance.” A cable’s characteristic impedance could be simply described as “how the cable looks to a high speed data pulse traveling down the cable” without getting into a lot of electromagnetic theory.

A cable’s characteristic impedance is expressed in units called “ohms.” You don’t need to worry about what an ohm is for purposes of this article.

Those of you who have some electrical experience are thinking that maybe you can measure the characteristic impedance of a cable by attaching your DC ohmmeter to the conductors and taking a reading. Sorry, it won’t work! You’ll just measure infinite resistance or pretty close to it. A cable “looks different” to a high speed data pulse than it does to a steady state DC voltage applied to it.

Sometimes a data cable will have its characteristic impedance stamped on the cable jacket, sometimes not. Most twisted-pair data cables will have an impedance somewhere between 100 and 150 ohms. A data cable specifically marked for RS-485 applications will have a characteristic impedance fairly close to 120 ohms.

Now as a data pulse travels down a twisted-pair data cable, you might say it “gets used to” the cable’s characteristic impedance. As long as the cable’s impedance doesn’t change unexpectedly the data pulses happily propagate along:

*** RS-485 WIRING TIP #1:

RS-485 will sometimes work with only the twisted pair connected between nodes, but you have a much better chance of making it work reliably if you also run the RS-485 Signal Common wire between the nodes. This topic really deserves its own tech article and we aren’t going to delve into it any deeper today! Just remember to provide the signal common hookup whenever possible.

Now RS-485 architecture allows many nodes to co-exist on a communications cable. So the transmitted data pulses will be read by all attached nodes. To keep from loading the transmitter too heavily, each RS-485 receiver has a high-impedance (12000-96000 ohm) input.

At each intermediate node (nodes not connected at the ends of the cable), the data pulses arrive on a 120 ohm twisted pair and leave on a 120 ohm twisted pair. The high impedance receiver inside the node does not load down the line, and so the data pulses happily travel on to the next node on the line:

*** RS-485 WIRING TIP #2:

For intermediate nodes on an RS-485 line, DO NOT make “stubs” that “tee” into the main twisted-pair trunk line! Run the incoming pair and the outgoing pair directly to the screws on the intermediate node as shown above.

So our data pulses are happily traveling down the twisted-pair communications cable being read by each intermediate node on the line until they come “to the end of the line” (cue ominous background music!).

At the end of the line, the data pulses traveling on the 120 ohm twisted pair suddenly encounter the high-impedance input of the last receiver on the line. This is known in transmission-line theory as “impedance mismatch” and it isn’t good!

When the data pulses hit the impedance mismatch at the end of the twisted pair, some of the energy in the pulses is literally reflected backwards up the line where it collides with the other data pulses. If the energy reflections are bad enough, the RS-485 receiver may not be able to interpret the data pulses correctly:

Obviously we’re going to have to do something about the impedance mismatch at the end of the line!  Fortunately, there is an inexpensive fix for this.  A small electrical component (a 120 ohm resistor) can be purchased and wired across the ends of the twisted pair.  Then, when the data pulses get to the end of the line they continue to see an impedance of 120 ohms due to the presence of the resistor.  Instead of reflecting, the energy travels into the 120 ohm resistor where it is converted into miniscule amounts of heat, and the data pulses fade away gracefully:

The 120 ohm resistors are inexpensive and easily obtained from distributors.

*** RS-485 WIRING TIP #3:

Only place 120 ohm termination resistors at the ENDS of the RS-485 twisted-pair cable.  Do not install termination resistors at any of the intermediate RS-485 nodes:



120 ohm network termination resistors placed at the ends of an RS-485 twisted-pair communications line help to eliminate data pulse signal reflections that can corrupt the data on the line.

We have heard anecdotal stories about how adding termination resistors did not help, and in some cases made matters worse!  That’s always possible, real-world network installations don’t always follow the assumptions made for a “typical” installation.  But on the whole the termination resistors will help network performance more often than they will hurt it.

Remember, network termination resistors are yet another tool in your network installation/troubleshooting toolkit.  They are not a cure-all for all network problems.  Keep a bag handy, and use them when it helps!


What Are Power System VARs?

Most people involved in building automation are familiar with kW, which is the rate at which a building is consuming energy from the power company. But there is another power system parameter known as VAR/kVAR which is less well understood. In this article we will attempt to dispel some of the VAR mystery.

The term “VAR” stands for “Volt-Amperes Reactive.” Guess we’re done here, right? What’s that? You were hoping for a little more explanation. OK, let’s dig a little deeper.

First, for any readers that are complete newbies to power monitoring, let’s explain the ‘k’ prefix frequently found on power system readings. “k” simply means “times 1000.” So three kV is three thousand volts, two kW is two thousand watts, one kVAR is one thousand VARs, etc…

What is a VAR?

Let’s begin our VAR discussion by saying that some of the electrical loads in a building (motors, transformers, classic style fluorescent lighting ballasts) use rising and falling magnetic fields to perform their intended functions. We call these “inductive” loads. When an inductive load is drawing power from the power company, some of this power is used to build up the load’s magnetic field during one part of the power cycle. The magnetic field stores part of the energy being delivered to the load.

Here is the interesting part – at a later point in the power cycle, the magnetic field which was built up earlier collapses. When that happens, the energy that was stored in the magnetic field is converted back into power which is returned to the power company! So with inductive loads, extra power is “borrowed” from the power company temporarily but is later “returned” to the power company. The extra power needed by inductive loads essentially bounces back and forth between the power company generator and the loads. This power is called reactive power and given the name VAR (Volt-Amperes Reactive) power.

VAR power does not show up on a conventional kW-only power meter. The kW meter only shows power that is actually consumed by the load. However, many modern electronic power meters such as Kele’s endicator will display both kW and kVAR power being drawn by a load.

Are VARs a problem?

So… if VAR power is not actually consumed by the load, but is returned to the power company, then there is no problem, right? Wrong. The extra VAR power, even though it’s not consumed by the load, causes larger currents to flow through the power company’s generators and power distribution system. So the power company has to install beefier generators and distribution equipment to handle that extra current flowing. Therefore they are not happy when a customer’s load is drawing high VARs.

To discourage customers from presenting high-VAR loads to the power system, the power company will sometimes install a VAR meter on a commercial or industrial building and tack a penalty on to the power bill if the VAR reading goes over a certain limit. This is normally not done for residential customers (good news for your home power bill).

How can I compensate for a high-VAR inductive load?

The good news is that there is a way to compensate for a high-VAR inductive load. There is an electrical component called a “capacitor” which also draws reactive power but stores the energy in an electric field instead of a magnetic field. Now, here’s the cool part – the capacitor stores and releases its reactive energy at the opposite times of an inductive load. That is, just as the inductive load needs extra energy to build up its magnetic field the capacitor is ready to give up the extra energy stored in its electric field, and vice-versa.

So by installing the correct amount of capacitance in parallel with an inductive load, the extra reactive power needed just cycles back and forth between the capacitor and the inductive loads, and the power company does not ever see the reactive power on their system.

Note we said the “correct amount” of capacitance. The value of the capacitance must match the value of the load inductance for complete cancellation of the reactive power seen by the power company. Of course, in the real world they won’t be perfectly matched; but still, the reactive power seen by the power company can be reduced to a low level.

If your building has a relatively constant inductive VAR load, then a fixed bank of capacitors can be installed for “nominal” reactive power cancellation. If your building has inductive loads that are dynamically cycled so that the inductive VARs fluctuate a lot, there are “smart” controllers that can measure the instantaneous inductive VARs and switch different values of capacitance in or out of the system to maintain on-the-fly dynamic cancellation of the inductive VARs.


The inductive VAR load presented by a building to the power company is always undesirable. You may or may not be penalized by the power company for a high-VAR load, depending on your situation. Capacitor banks can be added to a load to cancel the inductive VARs seen by the power company. Capacitor banks can be provided as fixed-value or dynamically-adjusted devices depending on whether your inductive VARs are steady or fluctuate widely. Kele’s endicator power monitor will give your building automation system the information it needs – both kW and kVAR, to control capacitor banks and minimize those utility penalties if they are causing you a pain in the wallet. Call Kele today to find out how!

Does Your Building Own its Energy Destiny?

Those of you who have read some of my past blogs have probably gathered by now that I’m fascinated by the intersection of building automation, energy and the coming Internet of Things (IoT) revolution. What captivates me most about this collision of previously tangentially related and/or non-existent industries? The monumental shift of perception I believe we are witnessing of the relationship between buildings and energy.

Historically, buildings have been viewed simply as high intensity energy users and rightfully so. Today, commercial buildings alone account for upwards of 40% of all electricity usage in the US at a cost of roughly $160 billion annually. Building automation arose decades ago to serve the need of not only assuring environmental comfort and safety but also helping lower a building’s energy load and the corresponding energy expenses borne by owners/occupants. There has been amazing progress in building automation and energy efficiency (e.g., better materials, mechanical and electrical systems controls advancements) and grid technology (e.g., smart meters, interval pricing, demand response capabilities) since those first days, but buildings are still simplistically viewed as merely a consumer of energy. Increasingly, however, owners are beginning to rethink their building’s relationship with energy and envision value they can derive from these capital-intensive, physical footprints far beyond a place to simply conduct business that only consumes (no matter how efficiently) energy. People are starting to talk about buildings both as tangible, competitive advantages and sources of new revenue streams and energy is the common denominator.

I read an article today that does an excellent job of highlighting this shift in mindset. The article’s author, Erich Gunther of IEEE (Institute of Electrical and Electronic Engineers), uses the term Smart Buildings 1.0 for the first integration interval of building automation and grid technology where the initial focus has fittingly been on increasing the bottom line via energy efficiency, demand response opportunities and automation technology advancements. The next phase, which he logically calls Smart Buildings 2.0, is, “less about efficiencies and more about corporate energy destinies”. This iteration implies greater control over where, how and when energy is both generated and consumed by a building. Some call this next step in energy control the ability to “island” or go “net-zero”.

So when and why might this ability to control ones “energy destiny” be important? That’s a bit of a rhetorical question, as most folks understand that a business’ productivity level is still very much tied to its access to reliable energy. During major power outage events resulting from natural disaster or grid failure, which have doubled (it’s important to note) over the period 2001-2008 according to Energy Information Administration (IEA), a business’ operations can grind to a halt without a holistic energy strategy/contingency plan while its competitor, located on the other side of the country (or world for that matter) and unaffected by the event, quickly picks up where they left off taking the customer relationship with them.  Control of ones “energy destiny” quickly begins to look like a vital piece of a proactive, forward thinking organization’s Business Continuity Plan.

Under Smart Buildings 2.0, business continuity, viewed through the lens of energy independence, will focus more on renewable, onsite sources of energy generation that allow a building or campus to continue business-as-usual during momentary grid outages and keep mission critical, customer facing functions up and running even in the event an outage that lasts for weeks. Although Gunther only touches on this lightly, I believe the building automation system will be the key enabler of an organization’s ability to ramp up or down power generation and/or consumption and dictate the hierarchy of where onsite generated energy is delivered. I believe that orchestrating both supply (i.e., power generation) and load (i.e., power consumption) side actions will be a critical function of tomorrow’s intelligent building automation/management systems. As buildings become more “energy autonomous” in the future, building automation systems will evolve dramatically to empower this complex level of inter-dependency with the grid and some level of self-sufficiency.

What role(s) do you see building automation systems playing in enabling an organization to own its energy destiny? I’d love to hear your thoughts on this or other energy related news affecting our industry.