Key Points:

  • Track lighting keeps the fixtures close to the ceiling, preventing them from making the space feel smaller than it is.
  • However, before installing them, it is necessary to calculate the entire track lighting load to ensure that your power supply can handle it.
  • There are two main methods for calculating track lighting load, the area method and the lumen method.

Track lighting systems can provide light fixtures in ceilings that cannot accommodate recessed lighting due to beams or other obstructions. However, before installation, you must calculate the lighting load that your system will have to bear.

But, how is track lighting load in residences calculated?

There are several ways to calculate track lighting load. The area method and the lumen method are the two most commonly used methods. The area method yields an approximation of the load, whereas the lumen method yields a much more accurate result.

In this article, I’ll show you how to calculate track light load using these two methods, as well as some less common ones.

How Is Track Lighting Load In Residences Calculated

Area Method for Calculating Track Light Load

Using this method an approximate calculation is done using the allowed lighting power density. If you’re wondering, how is track lighting load in residences calculated, this is one of the methods used.

In this method, we will need certain variables to calculate the lighting track load. The necessary variables include,

A = Given Floor Area (Square – Meter)

LD = Lighting Load Density (Volt – Amperes per Square – Meter)

To calculate the lighting load, assume L, the number of branch circuits have to be calculated as well. The NEC (National Electrical Code) code provides “Demand Factors” for calculating lighting loads.

The table provided by the NEC for lighting load is as below:

Lighting Load Demand Factors

Type of Occupancy Applied Demand Factor per Voltage (Volt – Amperes)Demand Factor (%)
Dwelling UnitsFirst 3000 or less at From 3001 to 120,000 at Remainder over 120,000 at100 35 25
HospitalsFirst 50,000 or less at Remainder over 50,000 at40 20
Hotels and Motels (Including apartment houses without provision for cooking by tenants)First 20,000 or less at From 20,001 to 100,000 at Remainder over 100,000 at50 40 30
Warehouses (Storage)First 12,500 or less at Remainder over 12,500 at100 50
All OthersTotal Volt – Amperes100

To calculate the lighting load with the area method, we will use this formula:

L = (A * LD) * Demand Factor

For example:

If your household has an area of 200 Square Meters and your required lighting density at any given time is 40 Volt – Amperes per Square – Meter at any given time, then your wattage capacity becomes:

(200 * 40) Volt – Amperes

Or, 8000 Volt – Amperes

Or, 8000 Watts.

As can be seen from the above table, we have to apply a demand factor of 100% and 35% respectively.

So, the approximate track load will be,

(3000 x 100%) Watts + (4000 x 35%) Watts

Or, 3000 Watts + 1400 Watts

Or, 4400 Watts

This is how track lighting load is calculated using the area method. Electricians will often use this method to troubleshoot your system. If you’re wondering how much electricians charge to troubleshoot, that’ll depend on the type of service you require them to perform, ranging from $50 all the way up to $2000+.

Lumen Method for Calculating Track Light Load

Using this method an accurate calculation can be done using engineering formula and standard lighting table values. In this method, we have to check the illumination level, which is calculated in Lux.

Illumination level is the amount of light, in Lux, falling on a surface. It is the luminous flux Lumens spread within the area (in square meters) of a designated space in the building.

1 Lux = 1 Lumen per Square – Meters.

The variables or factors needed to calculate lighting load using the Lumen method are as below:

  • Area (A)
  • Maintaining Illumination (MI)
  • Number of Lights (NK)
  • Coefficient of Utilization (CU)
  • Total Lamp Lumens (LL)
  • Light Loss Factor (MF)

Formula for the number of fixtures needed,

NF = (MI x A) / (NL x LL x CU x MF)

And if you use W Watts per fixture

Lighting Load, L = NF x W Watts

The maintaining illumination is fixed by the NEC, and you can find the coefficient of utilization on the product packaging or printed on the side of its body. The maintaining illumination or MI is an illumination rating provided by the IES (Illuminating Engineering Society) lighting handbook.

For example:

Let’s say, your household has an area of 200 Square Meters and you require 20 lights. The coefficient of utilization is 0.5 and the maintaining illumination is around 1000 lumens. Total lamp lumens are 2000, light loss factor is 30%.

Therefore, the number of fixtures,

N = (1000 x 200) / (20 x 2000 x 0.5 x 30%)

Or, 33.333 Fixtures,

Let’s round it up to 34 fixtures.

So, for 100 watts per fixture, the lighting load will be,

LD = 34 x 100 Watts

Or, 3400 Watts

As you can see, the required track lighting load for the same amount of area is significantly less in the lumen method compared to the area method. Therefore, it is an excellent method to reduce the excessive wattage usage as well as to reduce voltage between neutral and earth.

Summary

In this article, I have covered two of the most common methods that are used to calculate track lighting loads in residences. So, if you were wondering how is track lighting load in residences calculated, you should be an expert on the topic by now.

However, different settings require different methods to achieve an optimal result. Carefully asses your situation and requirements, and then choose the appropriate method that is compatible with your choice and electrical system for the optimal solution.