For any type of electrical lighting fixture, there are two different options to consider. One is the use of shunted sockets, and the other is to choose a non-shunted socket.
Both options can be used, but making the wrong choice will result in a lower life cycle for the bulb, and even an increased risk of an electrical short or failure in the lighting fixture. Ensuring the right choice is socket is critical for bulb and fixture performance.
The Shunted Socket Option
All shunted sockets have one path for the electrical current to flow through the socket. The non-shunted options in sockets use more than one path through the socket.
The choice of shunted over non-shunted is really a function of the type of ballasts in use. Fluorescent fixtures that have an instant start type of ballast use the shunted sockets. All other types of fluorescent fixtures, including those that dim, program start or those that are the rapid start or pre-heat types of ballasts, need to have the non-shunted options in sockets to prevent bulb failure and burnout.
The shunted design connects the two contacts within the socket. This allows for the single path of the current moving through the socket. By testing the contacts in the circuit, the presence of continuity in testing is proof it is shunted.
These same types of shunted options in sockets are also used for any type of “plug and play” options in LED bulbs. The non-shunted options in sockets are used for any type of LED bulb that is directly wired.
It is important to ensure any replacement of the socket is done correctly and meets the requirements of the specific ballast and type of light. When in doubt, always test the socket using a voltage meter to determine continuity before placing an order.