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How To Calculate T5 vs 400 Watt Metal Halide High Bay Wattage


Difference in Wattage: 400 Watt MH to T-5 High Bay

Calculating the cost benefits between a 400 Watt MH compared to a T-5 High Bay Fluorescent is a relatively simple calculation.  Calculating energy efficiency is actually simple subtraction problem. 

Looking at the 2 different fixtures above, we have to find the rated wattage of each fixture.   

A 400 Watt Metal Halide is rated at 456 Watts.

A 4 lamp T-5 High Bay (Depending On Manufacturer) is right around 200 Watts.fluorescent-t5-vs-400-watt-metal-halide

Now that we have that, we can do the math.

456 Watts - 200 Watts = 256 Watts Difference or 56% Less Watts. 

With this information we can now determine how much each of the fixtures will cost us annually.   

How To Calculate Kilowatt Hour (kwh)

A watt is only part of the calculation when figuring out how much your fixture is costing you.  But in order to show you how a watt fits in, we have to do a little more complicated math. 

By utilizing the wattages between the 2 fixtures, we can determine the cost difference between the 400 Watt MH and the T-5.  This will help you to understand how to determine the kwh. 

Here is the equation we need to use in order to do the math:

Fixture Quantity x Fixture Wattage = Total Watts.

Total Watts / 1000 = Kilowatts.

Kilowatts x (Hours of Usage) = Kilowatt/Hr.

Kilowatt/Hr x (Cost of Energy) = Annual Cost.

How Much Does It Cost?

Let's assume you have the following:

We are going use just 10 fixtures for this example (Fixture Quantity)

456 Watt Fixture (Fixture Wattage for Each) - or -

                                 200 Watt Fixture (Fixture Wattage for Each)

2000 Hours (Hours of Usage)

$.10 Per Kilowatt/Hr (Average Energy Rate Charged)

Annual Cost of the 400 Watt MH cost?

10(Fixtures) x 456 (Watts Each) = 4560 Watts.

4560 Watts / 1000 = 4.56 kw.

4.56 kw x 2000 hrs per year = 9120 kwh (Kilowatt) Annually.

9120 kwh x .10 = $912.00 to operate 10, 400 Watt Metal Halide for 1 Year

Annual Cost of the T5?

10 (Fixtures) x 200 (Watts Each) = 2000 Watts.

2000 Watts / 1,000 = 2.0 Kw (Kilowatt).

2.0 Kw x 2000 hrs per year = 4000 kwh (Kilowatt Hour).

4000 kwh x .10 = $400 to operate 10 T-5 High Bay Fluorescent

What's the Difference?

$51.60 Per Fixture Annual Savings

456 Watts - 200 Watts = 256 Watts.


$912 - $ 400 = $512 In Annual Savings (PER FIXTURE) or 56% Savings.

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Need Help?

Hovey Electric looks for the best lighting applications to satisfy the needs of our clients.  Each facility is a little different than the last. 

Typcially we need to see the inside of your facility first hand to determine what type of lighting you have now and to measure the lighting levels. 

Hovey Electric can perform a complete audit of your facility to determine what is right for you, for FREE.  Let's take a look at your facility, it's FREE and no obligation required.


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