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Lumens vs. Candela

What do You need to Know About Lumens and Candela?

Lumens and candela are both lighting measurement units, but they measure different aspects of a lighting device. Knowing about the difference between lumens and candela will help you choose lighting devices that suit the needs of your workplace. More importantly, this knowledge will ensure that you are not cheated by your lighting supplier who may try to convince you about the merits of a lighting device by quoting impressive lumens or candela numbers that are not relevant for your needs.

Defining Lumens and Candela

Lumens refers to the total amount of light emitted by a lighting apparatus and is denoted by L. The higher the lumens value of a lighting device, the greater is the area lighted up by it. On the other hand, candela refers to the amount of light emitted by a lighting device in a particular direction. Candela is denoted by cd.

The lumens unit does not consider the spread or divergence of the light being emitted by the device. But the candela value of a lighting device is concerned primarily with a focused beam of light. For instance, a standard fluorescent lighting device that emits a wide-spread beam can have a rating of 1,700 lumens and 135 candelas. But if the light emitted from this apparatus is narrowed and made to shine within a 20-degree beam, then its candela value will increase to 18,000.

Candela is also known as candlepower, and the reference is to those times when the candle was the primary source of illumination. The word candlepower was substituted with the term candela in 1948, and one candela is approximately equal to one candlepower produced by a candle of specific dimensions. In this context it is worth mentioning that the term Maximum Beam Candlepower (MBCP) is often used to refer to the maximum intensity of the focused beam of light emitted usually from the center of the lighting device, which is usually the source, and projected in a single direction.

The difference between lumens and candela can be better understood in the context of a comparison between a pencil torch and an incandescent or a fluorescent bulb. The torch has a high candela value because its light is concentrated into a single point and is projected in a single direction as a high-intensity beam. While buying a torch, you need not be concerned about its lumens value because you will only use this device to illuminate a very small area. On the other hand, an incandescent light or a fluorescent light bulb has a low candela value but a high lumens value because it emits a greater amount of light spread over a larger area than the pencil torch.

Why do You need to Know About the Difference Between Lumens and Candela?

Knowing about the difference between lumens and candela will help you choose the appropriate lighting device for your business premises. For instance, you need to install lights in your office premises to illuminate the objects in an area, like corridors and storerooms, so that your employees can move around easily without bumping into things. In such cases, you will need to concentrate on the lumens value of a lighting device.

The greater the lumens value, the more will be the amount of light emitted by the device, and the larger will be the area that will be illuminated by it. On the other hand, some of your employees may work with intricate devices and need overhead lights to shine directly on the objects they are working with. In such cases, you will have to buy lighting devices after comparing their candela values. Do not allow a retailer or a supplier cheat you into buying an expensive lighting device that has a higher lumens value but will not be suitable for your business needs.

Both the terms lumens and candela are generally used to measure the luminous efficacy of lighting devices used in industrial settings. The following equation roughly describes the relation between candela and lumens:

1 candela = 12.57 lumens

However, it must be noted that the lumens and candela values of various lighting devices cannot be directly compared to make a wise buying decision. The reason is explained below.

Make the Comparison

Because lumens and candelas measure two different aspects of luminous intensity, the performance of two lighting devices cannot be compared using both these parameters. The best way to ensure that you buy the most appropriate device for your business premises is to compare the lumens value (or the candela value) of two lighting devices and their corresponding watts. Watts refers to the amount of energy consumed by a lighting device during a specific period of time. When you buy lights after comparing like parameters, you can find energy-efficient devices that not only suit your business needs but also optimize your operational investment.

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