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The 9 steps to designing a low voltage shading solution

The Next Generation in Engineered Shading Solutions


DESIGNING A LOW-VOLTAGE SHADING SOLUTION 1. Defining Expected Functionality 2. Basic Motor Requirements 3. Wireless Control 4. Wired Control 5. Network Control 6. Selecting Power Supply 7. Correct Wiring and Layout 8. Complimentary Controls, Automation Inputs and User Interfaces

9. Shading Integration with Third Party Systems


1. Defining Expected Functionality Projects have a different set of requirements. Without an outline or an understanding of user functionality, a project can be under, or over-specified. It’s important to know the control topology or layout, for local, group, and global control. The need for automation input such as temperature, wind, rain, sun intensity, season, and time of day are significant factors in selecting system components. Knowing if the shading system requires integration with other systems such as lighting, HVAC, AV, building security and fire alarms adds a critical layer of planning. Lastly, does the user require higher level access via smart devices, computers and home automation equipment – both on and off site with remote capability.

2. Basic Motor Requirements Motors are rated by their lifting capacity in Newton Meters (Nm). For most applications, 6 Nm is the sweet spot in the lifting range. This amount of capacity will lift all sizes of shades with plenty of reserve capacity. An additional benefit is that multiple shade units can be coupled together onto one motor in order to minimize cost. For extremely large shades, specialty shades and long arrays of coupled units, a 10 Nm low-voltage motor can also be specified.

The noise created by the motor is a critical factor in providing a premium shading system. A noise level of 35dBA or less, should be the standard for quiet shade operation. Take note that each increase of 3 dBA, doubles the apparent noise emitted by a motor. Super quiet 33 dBA motors come in a larger 45 mm diameter form factor, and are appropriate for use when larger mounting spaces are available and noise reduction is an absolute requirement. Built in motor controllers with multiple input options eliminate most of the costly external control hardware, and provide design flexibility. Motors with an included dry-contact control method is preferred in all cases. Dry-contact is a low-voltage method of control that places all of the electronics within the motor itself. Simple on and off switch connections, signal the motor how to respond.

Programmable soft start and stop functions increase acoustic and visual comfort provided by the shading system. Intelligent motors will accelerate and decelerate rolling InSync Solar | 845.290.6370 | sam@insyncsolar.com | 1 Broadway Park Ridge NJ 07656

speed from programmed stopping positions. Motors that instantly start and stop often create clanking noises when shade hem bars jerk into frames and glass. The snapping on and off of motors is not appealing to users, and puts a strain on all of the components.

A well designed motor will have programmable rolling speed as a built-in feature for those special circumstances where speed may need to be adjusted. As the lifting capacity of a motor goes up, its rolling speed tends to go down. For some clients this may be an issue and adjustable rolling speed is a useful feature on some projects.

A premium motor should maintain a constant speed under all load conditions. This guarantees perfect shade hem bar alignment when multiple units are opened and closed at the same time. Large facades with many windows and shades require perfect alignment as small variances will be very noticeable inside and outside the building.

All motorized shades should have active and programmable obstacle detection. Expensive motorized shades can become damaged when they get block by packages and furniture carelessly left in their travel space. Obstacle detection can mitigate many of these issues by stopping the motor and returning it to a safe position.

Smaller diameter motors are excellent choices for reducing the size of fascia panels and ceiling pockets. At 35mm in diameter, 6 Nm and 10 Nm motors can provide aesthetically pleasing solutions for dual-roller shades, with solar mesh and blackout fabric, that traditionally required large mounting spaces. A 45 mm motor may be required when larger tube diameters are required for very wide shades and specialty units.

Low-voltage motors should be easy to install and program. The standard procedure for commissioning a shading system sometimes requires that each motor be disconnected and setup individually. This takes time and can be a frustrating procedure. Motors that can stay powered on while the system is programmed should be used when designing a project.

Low-voltage motors can run for longer periods of time without overheating. Always check the extended operation period for shade motors. 120 volt AC motors are notorious for short run times and thermal overload time out rests. Low-voltage DC motors have longer run times and usually do not overheat on a regular basis. Always check the continuous run time and look for motor that can run for at least 5 minutes without timing out.

Low power consumption in operation, and while at idle provide long term economy. Efficient DC motors should use less than 70 watts of power with 50 watts or less being the sweet spot. This extends motor life, saves power and reduces overheating. Shading motors with built in wireless and dry contact controllers require power even at idle. Well- designed motors use less than 0.5 watts while in the idle mode.


Low voltage motors should have a UL certificate. To ensure quality engineering, design and safety even low voltage motors should have some form of independent testing to verify performance. Poorly manufactured offshore motors generally do not have this approval and is the main reason for their lower cost.

3. Wireless Control There are two wireless control methods – uni-directional and bi-directional command flow. In uni-directional command flow, motors only can listen for commands, and controllers can only transmit commands. In bi-directional command flow, motors and controllers have the ability to listen, and transmit information. A bi-directional system allows for the real time flow of commands, acknowledgements, status reports and inquiries across the system.

Motors that have built in wireless control, and concurrent dry-contact provide an economical solution. Wireless control is becoming the de facto standard for shading systems. It provides a wide range of functionality within the range of the radio reception. It’s the perfect solution for local, group and global control. Dry-contact provides an additional concurrent layer of flexibility and control required on some projects. Alone or mixed and matched, within the same system, they provide a cost effective control backbone for any shading project.

Wireless-Mesh-Network motors provide enhanced wireless functionality. Standard wireless motors are usually limited to around 65’ for command reception from wireless

handheld and wall mounted controllers. To address this issue, mesh network motors can both receive and send information. When meshed together, motors will re-transmit signals to more distant motors and significantly extend the wireless range.

Meshed motors provide control feedback across the wireless network. The bidirectional exchange of information in a meshed network allows motors to report their position in real time to the controllers. This feature allows the use of a slider bar for ultimate shade control. A simple touch anywhere on the slider will bring the shades to any position between 0 to 100% of their travel.

Meshed motors use an encrypted rolling code for robust security. The use of an encrypted rolling code greatly reduces false signals across the wireless network. The newer control protocols are 30 times faster in recognizing and correctly acting on commands. Command encryption protects the system from unauthorized users and competing systems in the same vicinity.

4. Wired Control Larger projects and global control may require dry-contact input. Many systems can be designed using only dry-contact control with up to 8 motors on a single switch contact. Master timers, sun sensors, wind sensors, HVAC and security systems that invoke global control usually work best with dry-contact.

Motors should be compatible with a wide array of complimentary lighting, HVAC, AV and security systems. Manufactures often push software driven integration with third- party systems falsely assuming someone can make it all work. The success of these situations is completely dependent on the skill and programming expertise of an expensive systems integrator.

Dry-contact control should be the method of choice for integration and is based on a series of relays that reside on whatever system is designated as the master controller. This will usually be a home automation processor that coordinates all of the connected systems. As shade movement is required, third party relays issue a dry contact command to the shade control unit.

Dry-contact integration clearly establishes vendor responsibility when things don’t work. Since there is no common software and digital data is not exchanged in dry-contact it is easier to determine whose system is having a problem. By acting as a “firewall”, dry- contact eliminates one system taking down all systems. Each system is allowed to live freely in its own world taking data free input and using within the context of its own operating structure.

5. Network Control Network based motor systems may be preferred for higher levels of control on large projects. To un-tap even higher levels of control, network or bus motors can be used effectively. The basic characteristics described above are augmented by centralized

controllers that communicate commands digitally. Motors that have digital and dry- contact capability allow for the design of very powerful shading systems.

Network based systems should be designed carefully. The design and installation of a digital network needs to be performed by experts in digital communication. When done correctly these systems are the pinnacle of shade control and operate with limited maintenance and service. Poor design and installation can create systems that are difficult to commission and operate. Always utilize a shading consultant when contemplating the use of digital control.

The complexity of a network based system adds to the budget. Network based systems provide an almost unlimited level of control to the end user. Before utilizing these systems determine if the project actually requires this level of control. The budget for any shading system increases as the control requirements are expanded. Many projects can be successfully designed and installed using wireless and wired control layouts as an option.

6. Selecting Power Supply Power for shade motors may be wired or battery supplied. Standard wired low-voltage motors require 24 volts of DC power. This power is supplied by transformer panels or plug in transformer units. Motors with internal battery packs are becoming more common and provide autonomous shade units. An autonomous shade unit has built in power and wireless control for a truly “hang and use” solution.

The NEC codes regulate the use of 24 volt power supplies. The NEC has reduced expensive wiring requirements for low-voltage power distribution within a building. In exchange, and to minimize fire and electrocution risk, the NEC has set a limit of 100 watts of power on any single transformer/wire combination.

What does the 100 watt limit mean when designing the power supply system? At the standard voltage of 24 volts DC, no more than 4 amps of power should be provided by the transformer supplying the power. For most installations this means one motor per transformer and one motor per supply line.

Why is the power configuration one transformer per motor? Most low-voltage motors utilize 3 amps or less per motor. Some motors may require only 1.5 amps to function correctly and manufacturers allow two motors per supply line. Power requirements, transformer supply and wiring capacity need to be carefully calculated to avoid overloading a power distribution system. Best practice is one transformer per motor with a dedicated power supply line.

Limited Power Source (LPS Pass) or Class 2 certification ensures that power supplies are safe. These certifications are printed directly on a power supply and should be required for all low-voltage power supplies. Supplies with these certifications are inherently safe from fire, electrocution, overheating, short circuits, and over-voltage conditions. Do not confuse Class 2 with Class II. Class II refers to the level of insolation used in power supply construction.

Beware of larger power supplies using fuse distribution panels to limit current. A 20 amp power transformer is often fused thru 10 two-amp fuses to distribute power. These power supplies are not LPS Pass or Class 2 certified, and while they are safe in and of themselves, they violate the NEC code when used with low-voltage wire to distribute power.

Codes are written to protect all people including foolish ones. The use of fuses is certainly an acceptable way of limiting power. The NEC however recognizes the approved fuse value can be mistakenly replaced with one of a higher value. Placing a 10 amp fuse in a slot that requires 2 amps, subjects building wire to 240 watts of power. This is two and one half times the maximum limit and dangerous.

What form factors are acceptable for power supplies? The panelized version is usually 10 DIN rail mounted transformers in one electrical enclosure. For larger systems this is the preferred way of providing power. Smaller and simpler plug in transformers can be used where budgeting and space become an issue. These smaller units can be distributed through the project to provide power closer to where the shades are located.

Are plug in transformers safe? Yes, in fact they have the same components used in DIN rail units packaged in a smaller form factor. They are usually limited to 60 watts of power, or 2.5 amps, meaning they may not be suitable for larger motors. There is absolutely no impact on shade performance using this solution.

What to look for if thinking about a battery powered motor. Always look for motors with internal rechargeable batteries. Utilizing USB chargers and cables is a plus for recharging without proprietary components. The best motors can operate for 500 up and down cycles on a single charge, and be recharged 250 times without replacement. Battery motors should have all of the super quiet functionality as that of the power supply versions and operate in exactly the same manner.

7. Correct Wiring and Layout: Always use the correct low voltage power supply wire. Voltage drop is usually forgotten when planning the wiring layout for a project. Voltage drop increases along with the length of the wire run. Systems using low voltage are more prone to a loss of performance when not getting the correct amount of power. A 120 volt light bulb loosing 5 volts of power will work just fine. A 24 volt motor will not operate correctly at 19 volts.

Voltage drop calculators are helpful in choosing the correct wire. Many online voltage drop calculators are available to assist in specifying the correct wire gauge for your system. In any case, do not consider using less than a 16 gauge wire. To minimize on wiring costs consider distributing power panels and transformers around larger projects.

DIN Rail transformers with adjustable voltage outputs are helpful in balancing available power. When the voltage drop exceeds 1 volt, it is time to increase wire size or adjust transformer voltage level. Transformers that can be adjusted individually allow all of the motors to get exactly 24 volts while running. This adjustment compensates for varying lengths of wire creating a balanced power supply system.

Use correctly rated wire for proper insulation protection. Low-voltage power lines often run close to higher voltage cables. The NEC expects low-voltage cables in these situations to have an insulation rating equal to or exceeding the voltages in the surrounding environment. CL and CM, UL rated cables, should always be specified. These cables come rated for 150 and 300 volts. It is best practice to use 300 volt rated cables in all of the wiring specifications.

Use riser and plenum rated wire as required. To minimize flame spread, toxic gases and smoke cables are rated for use in vertical walls and in horizontal ceilings. Wire runs in walls are considered usually riser locations, while ceilings are usually considered plenum locations, especially if conditioned breathing air runs thru these spaces. Plenum rated cable is more expensive than riser rated cable but essential for occupant and building safety.

Remember wire run length increase with travel up, down, and through walls. A straight line distance of 25 feet can quickly become 50 feet as wires rarely take a direct route from point A to B. Not taking this into account can vastly underestimate the amount of wire, installation cost and most importantly voltage drop.

Network based systems require the proper data cables. Cat 5 and Cat 6 cable have become the universal “go to” for almost any project including data. Unfortunately, these cables are designed for ethernet data distribution and may not work correctly with network based shade motors. Most shade control systems use a variant of the serial communication standard and are referred to as RS232, RS485, CAN bus, etc. Each manufacturer may have a proprietary name and protocol for their individual system. Regardless of name or brand data cables need to be specified carefully and should never be referenced generically.

What is the correct data cable for the project? Each manufacture will specify the cable that they have tested and is known to work. Often, they create proprietary expensive cable containing both power and data. The cost of these cables can quickly eat up a budget. Using the wrong cable, associated manufacturer’s equipment and approved wiring layouts often voids warranties and manufacturer support. Proceed carefully when selecting cable. Always use a professional Engineered Shading Solution Consultant on these types of projects.

I know someone who set their system up with cat cable and it works fine. Good for them and they got lucky. There is always room to push a network specification and get acceptable results. However, no one wants to design, purchase and install a system that doesn’t work because the limits were exceeded. There is no known way of predicting with certainty how an “out of spec” cable or wiring layout will work. Fixing the problem, after the fact, is very time consuming and expensive.

8. Complimentary Controls, Automation Inputs and User Interfaces: The four levels of control are motorization, automation, integration and Wi-Fi based. Each of these terms means something different when designing a shading system. As the level of control increases the complexity of the system design, and the corresponding budget, increases as well. This is why it is important to ascertain the control expectations of the client before specifying the requirements of any shading system.

Motorization comes in two varieties for shading systems. The first approach is what is referred to as “Set and Forget” control. This is an “unsupervised” motorized control technique where a button is pressed and the shades move to their programmed position. The second approach is referred to as “supervised” control where the user must hold a button for the shades to continue movement. Whenever children can come into contact with the shade itself it is always prudent to use supervised control. Yes, obstacle detection can assist in preventing entrapment, but supervised control adds an additional layer of safety.

What is automation? Automation is a process that allows motorized shades to accept input from sensors and other shade control devices. When input is received the shades will automatically perform pre-programmed movements without the need for user interaction. Automation also permits repetitive and predictable shade movement when certain conditions exist. The best examples would timer and calendar controllers, interior light intensity and temperature sensors.

9. Shading Integration with Third Party Systems

Integration ties the shading system into other building systems. Integration is the process of combining the functionality of several different systems together. Shading is often expected to work in in conjunction with lighting, HVAC, AV, security and fire alarm systems. Integration is dependent on having a central building controller that is programmed to call up each system individually or in groups to perform a certain function.

Shading system integration can be “tenant” or “access permission” based schemes. “Tenant” based systems do not usually provide a concurrent shade control system. Rather, the shades are merely a system that can respond to a centralized automation system when the proper commands are issue. An “access permission” system is a fully functional shading system that allows a third party permission to issue shading commands when they are needed.

“Access permission” systems are easier to diagnose and determine vendor responsibility. When integrated systems fail it can sometimes be difficult to determine vendor responsibility. Having a fully functioning shade control system, even a basic master control, can quickly determine if the shades are at fault. Some clients may not want two sets of controls in an area for aesthetic reasons. Here a master or group control switch, located in an IT closet, is all that is needed to sort things out.

User input control comes in a variety of formats. The most common forms of user control are wall mounted switches and handheld controllers. Advanced systems may have remote sensors and controls that operate the shades in a concurrent fashion. When properly combined the array of controls is designed to satisfy the project’s operational requirements. Well-designed shading systems should allow users to add-on and modify existing controls without having to completely re-design the system. The use of phone and tablet control is a feature many clients like.

Dry Contact wired wall switches. Dry contact push button wall switches are available with 2 to 12 buttons and many configurations in between. Most users are looking for a Decora style switch face and cover plate in colors available for standard electrical switches and outlets. Custom label engraving should be considered to assist users in their command selection. Use caution when placing low voltage switches in wall boxes containing high voltage. If in doubt about safety do not gang low and high voltage devices.

Wireless wall switches are a simple way to provide fixed control points within a space. To provide the easiest installation these units are surface mounted anywhere and use regular AA batteries as their source of power. Life expectancy of the batteries is 2 years with 10 uses per day. Single channel and six channel units are available for a Page 15 of 16 range of flexible control options. When meshed with bidirectional motors control range extends out up to 500 meters for larger projects. Touch-less wall-mounted controls use hand gestures to invoke shade movement and are great for use where gloves are worn, places where infection control is required or wherever wet dirty hands may damage button controllers.

Wireless handheld remotes provide portable control and advance shade control. These controllers are comfortable on a tabletop, in your pocket or hanging on a wall as a multipurpose hand / wall controller. Advanced units can control an entire project with 99 channels and an LCD screen to provide more programming and control options. Bidirectional controllers will have a slider touch bar to allow “go to positioning” at any point from 0 to 100% of travel. Timer and calendar functions are useful controller options and are available on the LCD versions of handheld controllers.

Wi-Fi controller apps are becoming the preferred way to control shading systems. When the power of a Wi-Fi network is coupled with the shading system a full range of remote functionality becomes possible. A Wi-Fi bridge module resides on the local network as an addressable device. Phones and tablets can access this address and issue commands, even from remote locations. These commands are converted into wireless signals that are sent out to the individual shades. Higher level commands are possible since the app is capable of issuing complex commands based on things like time, day, date, shade group, shade position, etc.

Advanced network devices for building management are available for larger shading projects. Often a project will require a building management system. Shades are a key component in any building management system and require intelligent control overlays. Using DIN rail mounted modular components a wide variety of shading devices can be tied together for control via a PC, browser, tablet, LAN connection or Wi-Fi network. Since the design of these systems involves careful design and engineering a shading consultant is usually recommended for these projects.

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