How To: T8 and T12 LED Fluorescent Replacement Tubes

Choosing the right LED fluorescent replacement tubes can be confusing due to the myriad of product types and installation options. We at Michrotech have created this guide to assist in the process and help you make the right choice for your specific projects.

How Do I choose the Right Tube Replacement

The first and most important step in choosing which product is right for you is to decide on the installation method you would like to use. The installation method will largely vary on what type of existing fixture technology you have– either T8 or T12.
To figure out what you currently have installed, it is best to remove a bulb from the fixture and read the markings on the end. This will reveal a lot about your current fluorescent tube and usually indicate if the bulb is T8 or T12.
If no markings are available, the size in diameter of the tube is the easiest way to determine the type you have installed.
T8 tubes are 1-inch in diameter and T12 tubes are 1 1/2 -inch. If you have a tube that is very small in diameter (5/8 inch) you have a T5,and thus the remainder of this discussion will not be of use in terms of helping retrofit this application.
Now that you know what type of tubes you have, the next key is to understand the type of ballast. In general, T8 use electronic ballasts while T12 use magnetic ballasts. Opening the fixture and examining the ballast will give you the ultimate answer as to what type of ballast you have; but, in general, the older the fixture, the more likely it is to have a magnetic ballast.
With the ballast and tube type considerations out of the way, let’s discuss the various replacement options.


Ballast Bypass or Direct Wire LED Tubes?

The oldest but also least expensive and most widely installed option is the ballast bypass or direct wire LED fluorescent replacement tube. Instead of building expensive circuitry inside to enable the function with a ballast, this option instead allows the user to bypass the ballast entirely and run directly off of the line voltage at the installation.
Due to potential safety hazards of interacting with line voltage, (which can be as high as 277V in commercial applications), safety testing organizations such as UL have introduced standards to ensure that this product can be installed safely. The result is that most products in this category have to be installed with the line voltage input into one side of the tube.

Non-Shunted Rapid Start Tombstones are needed


This introduces a unique requirement in that the sockets must be of the T12 or “Non-Shunted Rapid Start” type. If you have a T12 fixture, you are in luck, as you have all the necessary hardware already. T8 fixtures must have the input side sockets changed to T12 sockets of the “Non-Shunted Rapid Start” type, as T8 sockets have a circular conductor that will not allow them to properly separate the line and the neutral sides of the circuit.
While the wiring is actually quite simple and can be performed in minutes per fixture, it is usually recommended, or in the cases of commercial properties required that an electrician perform this task. 
Despite the more complex installation requirements, ballast bypass tubes have large advantages in that their unit cost is lowest versus all other options–an important consideration in the case of a very large project where every dollar counts. For users with T12 fixtures, they offer a compelling option as well due to the necessary socket hardware already being in place. 

T8 Electronic Ballast Compatible LED Fluorescent Replacement Tubes

A relatively new option is the electronic ballast compatible LED fluorescent replacement tubes. As their name might suggest, they are meant to work with electronic ballast installations and therefore will notfunction with magnetic ballasts nor will they function without ballasts. Industry data suggest that this combination alone accounts for over 1.2 billion tube lights, thus they are perpetually growing in popularity. 
Like the universal tube technology described below, installation is as simple as pulling out the old tube and swapping the LED tube in its place. Due to the enormous variety of electronic ballasts on the market, many manufacturers have actually done compatibility testing and have developed a full list of compatible ballasts that their LED tubes will work with.
The downsides to this option are once again a higher per unit upfront cost, alongside the continued worry that if the ballast fails the LED tube will not illuminate. Individuals and organizations have to weigh these potential pitfalls against the ease of installation and lack of downtime. 

Hybrid (T8 Electronic Ballast Compatible /  T8 or T12 Ballast Bypass LED) Fluorescent Replacement Tubes

Some manufacturers have recognized the opportunity to provide LED tube lights that work with Electronic Ballasts (T8) or have the ability to bypass ballasts when the ballast no longer works. This has given rise to a new category, the hybrid tube light. Hybrid tubes work with T8 electronic ballasts but can also be wired directly like a ballast bypass tube light should the ballast fail or if a facility has a mixed environment with T8 and T12 that require both wiring types. This is an advantage for mixed type facilities because the same tube light can be used with a quicker implementation time. Hybrid tubes also allow for the tube light to quickly bypass the ballast if the ballast fails due to their dual operating nature. The primary downside to hybrid tubes are their higher cost and in some cases lower efficiency versus ballast bypass options.

Universal (T8 Electronic or T12 Magnetic) Ballast Compatible LED Fluorescent Replacement Tubes

The newest, most costly but also easiest to install, these LED tubes will literally work with any type of existing technology– be it T8 (Electronic Ballast) or T12 (Magnetic Ballast). The install is as simple as taking out the old fluorescent tube and installing the LED tube. These are a great choice for a homeowner or smaller facilities where the primary goal is total power reduction and no downtime for installation.
The major downside of these options is the up front per unit costs, which can be amongthe highest. Additionally, since the ballast is still in place it is still a maintenance concern. This is especially critical in T12 magnetic applications where new ballasts can no longer be procured.

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