As with so many parts for lighting fixtures, there are options in just about every size and type. This is certainly true for the T-12 sockets were you have the option to choose from shunted and non-shunted models.

For anyone considering their own repair of fluorescent fixtures, understanding the difference between shunted and non-shunted T-12 sockets is important. Replacing an existing socket with the wrong part will result in a significant problem and one that can end up as a more costly repair.

Shunted and Non-Shunted

The shunted T-12 sockets will allow power to flow between the two contacts in the socket, which are the metal insets within the socket. When the electrical voltage meter is set to continuity you will hear a beep when the positive and negative ends are placed on the two metal components.

A non-shunted T-12 sockets connector will not make the beeping noise as there is no flow of electricity. While most fluorescent fixtures will be the shunted variety, there are some non-shunted models out there.

Non-shunted T-12 sockets are typically used with a programmed start ballast. It will have the standard bi-pin base, and from the exterior will look just like the shunted sockets, so you cannot go by looks alone.

Determining the Bulb

For those new to working with fluorescent fixtures, having the right socket for the bulb is critical. The diameter of the bulb is actually what designates the need for T-12 sockets. The diameter of bulb needed for this size of socket is 1.5 inches. For a smaller diameter bulb, typically 1 inch in diameter, you will need to choose a T-8 socket or a T-5 socket for a 5/8 inch diameter bulb.

Besides measuring the bulb diameter, this information should be found on the end of the bulb. You will not typically find any indication of the size on the T-12 sockets, although someone experienced in working with fluorescents will be able to tell the size very easily.

Making a Purchase

When you need more than a few T-12 sockets, buying in bulk makes a lot of sense. Not only do you get a much lower cost per unit price, but you can also choose an online company that has a top reputation.

Many of the best T-12 sockets are made right in the United States. Look for companies that are based out of the USA and also offer all the fluorescent parts you may need to order.

At H.H Fluorescent Parts, we offer a great selection of T-12 sockets for your home, commercial or electrical service needs. To see more or to order visit us online at

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