When it comes to installing high bay lights—and correctly spacing them—in a large space, there’s good news and bad news. The good news is that the lights available today are radically better than those available only ten or twenty years ago. The lights are powerful, efficient, and flexible enough to light any space. The bad news is manageable, don’t worry—it is simply that there are many factors to consider. It can be a little confusing.
Let’s run through the major issues. The goal here is a basic literacy on the topic. We’ll save the complex formulas for another time.
Spacing Lights According to Application
Your application should be one of the top guides in spacing your lights. In short, some spaces need more light than others. Manufacturing facilities, big box stores, workshops, and warehouses with a lot of product handling require the most light and a high lighting power density (LPD) (which we’ll get to in a minute). Storage rooms, gyms, and warehouses with low activity require less lighting.
There is no guide to exactly how much light is needed for each application, but knowing what end of the spectrum you’re on (use-wise) will help you get started. It sounds obvious, but the more light you need, the more lumen capacity you need to install. (Brightness is measured in lumens.) Also, if you your facility needs good visibility, you will have to be more careful in designing the spacing—if your lights are too far apart, you risk creating gaps in your coverage.
Floor Area and Ceiling Height
Perhaps the two biggest factors to consider in spacing high bay lights is your floor area and your ceiling height (or, more specifically, your mounting height). These issues are fairly common sense. The more space you have, the more lights you’ll need; and the higher your ceiling is the more light you will need from each source..
This calculation, at its simplest, resembles a basic middle school math problem. You are roughly taking the square footage of your facility and dividing it by the coverage of a single light. That gives you the number of lights you will need. (For example, if your floor is 1000 square meters, and a single light covers 100 square meters, then you will need around 10 lights.) But it’s not quite that simple. You also need to calculate how high your lights will be mounted. The higher you raise a light, two things happen. The beam gets wider (more light!). But the beam also gets weaker (less light).
You would also need to take into account the shape of the space—rectangular, square, irregular, etc. There is little need, for example, to install a light near a wall. Ideally you want the lights evenly distributed across your ceiling. Again, some of this is common sense.
Most high bay lights will come with specs that tell you the shape and intensity of the beam. This information is sometimes called the fixture’s photometrics. For example, a UFO LED light (the saucer-shaped lights popular in warehouses) like the IntrinsiX CIRCA light has a spec sheet that indicates an “average illuminance effective figure” for its beam. The photometric shows you that the width of this light’s beam (and square footage of coverage) at different distances (i.e. mounting heights). It also shows you the light’s intensity at those distances; this is measured in lux (symbol: lx). A lux is a unit of light’s intensity and is the equivalent of one lumen per square meter.
By using these two numbers—the width and intensity of the beam at different heights—for a particular high bay light, you can begin to calculate how many lights you need for your space and how far apart they need to be.
But there are also some rules of thumb that people in the industry use. One of them is that the mounting height is roughly equal to the distance between your lights. In other words, if an light is mounted 20 feet up, it should be roughly 20 feet from its neighboring light.
That rule of thumb is great for giving you a rough idea of how to space your high bay lights, but there will be long-term benefits if you can get a more accurate figure. A little bit of number crunching goes a long way. Also, there are many experts out there who can help you with this calculation, including those at Duralec who have been doing this for years.
The Type of Light Fixture Matters
The two most common kinds of LED high bay lights vary in how they distribute light. These lights are the (aforementioned) UFO light and the linear light. The UFO light is roughly a point source and casts its beam in the shape of a cone. Its area of coverage is roughly a circle.
The second kind of light is a linear high bay light and resembles a flat-panel fixture. As you might expect, its area of coverage is more like an oval. These shapes need to be factored into the overall spacing of your lights.
Another fixture feature that affects spacing is the option for dimming. Many LED high bay lights come with dimmability, and this feature gives users more options in how they mount their lights. For example, having dimmable lights would allow you to space the lights more closely for powerful brightness and visibility but would give you the option of running the lights at lower wattages at certain times of day or in certain sections of your facility. The end result is a lighting array that is flexible in its brightness and efficient in its energy use.
When Correct Spacing Is Required by Building Codes
In some cases, a certain amount of lighting is required by building codes or workplace-safety regulations. The Occupational Safety and Health Administration (OSHA), for example, requires that employers “shall ensure that each work area and walkway is adequately lighted whenever an employee is present.” This standard specifies different light intensities for different types of work spaces (warehouses versus changing rooms versus offices, etc.). Another standard is the International Building Code’s (IBC) requirement for proper lighting in exit areas and passageways. This code requires different lighting power densities (LPD’s) for various egress areas. The code measures LPD’s in watts per square foot. Other lighting standards have been published by the National Fire Protection Association (NFPA) as well as the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE).
In some cases, meeting these standards would require that you create the proper degree of spacing to provide the necessary lighting intensity. However, the standards do not mandate an amount of spacing. Being mindful of proper spacing is key to meeting these lighting standards.
The Benefits of Correct Spacing of High Bay Lights
When designing a network of high bay lights, it’s important to try to get the spacing right the first time. No one wants to do an installation twice. Figuring out the spacing on paper—perhaps with the help of an expert—could save you loads of trouble and money during the process.
There are many long-term benefits, as well. Correct spacing will ensure that your lights work at their most efficient levels. Planning it correctly might prevent you from over-buying and having more capacity—and energy usage—than you need.
A well-spaced grid will also ensure the most effective lighting. Proper lighting is necessary not only for visibility and productivity but also for worker safety. LED high bay lights are ideal for worker wellbeing, as well, as they are free of flickering and limit eye strain and fatigue. A well designed array that produces high-quality light also looks professional and attractive.
To discuss the issue of how to space high bay lights in any kind of situation, feel free to reach out to a Duralec expert today. We have years of experience creating lighting solutions across the Midwest.