By Donna Rider

There are several elements to consider when putting together a commercial HVAC control panel. For a good panel design, consider the environment in which your panel will be used: Is it indoors or outdoors, or is it possible that it might get wet due to cleanup procedures? In addition, certain government guidelines must be met regarding power input and output requirements, the types of components required and energy efficiency. Further, leave enough room in the design to allow proper labeling and a logical layout to make repairs easier.

Where Should You Start

The first step to ensuring best practices during commercial HVAC control panel design is to determine how the control panel will be used. Write down a list of requirements for the machinery this panel is going to control. It may take a few revisions to figure out exactly what your needs are. Be sure to consider future expansion possibilities, so that you leave room in the panel design to accommodate growth.

Choosing Components

Once you have a list of your requirements, organize and precisely define the components you need to accomplish the work. Always start with simple components of relays, switches, etc., as they produce less heat than more complex components and are energy efficient. If necessary, go to programmable logic controllers (PLCs), etc.

For the control box encloser, check the NEMA.org standards. An industrial HVAC system should have a control box enclosure with the rating of, at least, NEMA 4X.

It’s Time to Start the Paperwork

Create a physical layout drawing of the control panel to help visualize how your components will come together, along with an electrical layout drawing to give you an idea of the power needs of the components.

The end result should include functional, input/output, power distribution diagrams and a control box panel layout, along with a table of contents for easy reference.

Lay out components in a logical manner with attention to power needs, heat dissipation and adequate space for expansion. Labeling components is very important, also. Labels on the diagrams must match the labeled components on the control panel, so be sure to allow room for component labels on all diagrams.

Follow Documented Guidelines

NFPA 79: Electrical Standard for Industrial Machinery provides safeguards for industrial machinery to protect operators, equipment, facilities and work-in-progress from fire and electrical hazards.

Check out the National Electric Code (NEC) clearance requirements for power wiring.

Electrical systems are grounded and bonded to the building’s steel structure. The NEC (National Electrical Code) details several regulations pertaining to grounding and bonding, due to safety reasons.

Mounting Wires and Wireway

Provide enough space so that the wiring can be brought neatly to each panel component. A good control panel design allows enough room for the internal panel wiring and the wiring to the input/output terminals. Design the wireway to allow enough space to bring the wiring neatly to each panel component and terminate properly.

A power disconnect switch is commonly located in the upper right of the panel. Best practices for HVAC control panel design is to group similar voltage-rated components together. Start with the components that have the highest voltage levels at the top of the panel, and work down from left to right, placing the lower voltage level components toward the bottom right. This design is logical and helps with troubleshooting.

Biography:

Donna Rider is a Technical Writer with more than 18 years experience researching, developing, managing, and producing on-line documentation and training videos. Ms. Donna Rider gained her expertise in technical writing during her highly successful career in several leadership roles. Specifically, Ms. Donna Rider wrote technical documents to assist the Help Desk Technicians troubleshoot calls from customers at Gateway and Wells Enterprises.

 

Sources:

  1. https://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=79
  2. http://www.oempanels.com/electrical-control-panel-design-basics
  3. https://www.controleng.com/articles/four-aspects-of-good-control-panel-design
  4. https://www.controldesign.com/articles/2016/control-panel-design-starts-with-the-basics
  5. https://www.mpofcinci.com/blog/industrial-control-panel-design-guide
  6. https://www.progress-energy.com/assets/www/docs/business/Grounding.pdf
  7. https://www.osha.gov/dts/otpca/nrtl/ul.html
  8. https://electrical-engineering-portal.com/safety-clearance-recommendations-for-electrical-panel
  9. http://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards?mode=code&code=79
  10. https://www.nema.org/Products/Documents/nema-enclosure-types.pdf