Working with lighting is a complex undertaking. It involves the understanding of a variety of diverse components. When they work together correctly, you have a room that can come alive with the warm glow of lamps and other forms of lighting. One wrong step and it can all go horribly wrong. Place the wrong bulb into the wrong socket and you can cause an electrical shortage or worse. This is one reason why it is so important to know what shunted lampholders are.
What Is a Lampholder?
A lampholder has several different names. You can refer to them as:
- Lamp holders
- Lightbulb sockets,
- Lamp sockets
- Tombstones
- Lamp receptacles
- lamp jacks
All indicate the same device – a means of providing electrical connections to the lamp, while giving it mechanical support it in the fixture. Sockets connect the lamp to an electrical circuit. The existence of a lamp holder also makes replacement of bulbs and lights easier and safer.
Sockets or lamp holders come in different sizes and styles. They are also divided into two basic types. These are shunted and non-shunted. The former type is commonly employed for approximately 90% of all fluorescent fixtures.
What Is a Shunted Lampholder?
Shunted lampholders are those that are connected. In other words, they feature electrical contacts that are internally connected. The design provides a single route for the current to flow from the ballast, through the lamp holder to the pins. The positioning of this shunt usually makes them invisible. Basic characteristics of a shunted lamp holder are:
- Both sides of the lampholder join together
- Direct circuit contact at the socket, allowing the energy to move quickly and without any trouble from one contact to the next – i.e. positive continuity
- Performs as a jumper
- Defending the lamp cathode
- Working to provide longer life to the light
- Makes the light come on instantly which is one reason why it is common for use in fluorescent lights
Confirmation of the socket type may be defined by the use of a voltage meter set on “continuity.” A reading of positive continuity indicates the lamp holder is shunted.
Using Shunted Lampholders Correctly
A shunted lamp holder is not appropriate for all types of lamps. In the case of a LED retrofit, for example, the shunted socket requires replacement with a non-shunted type. If the wrong type is employed, serious problems are the result. Not only are you ignoring the stated regulations regarding lamp holders, but also, by placing the wrong bulbs into shunted lampholders you can melt the sockets, destroy the tubes and create the conditions for an electrical fire.