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Ministry of Defence BT Inmarsat Science & Technology Facilities Council

SC vs LC - What’s the difference?

Optical connectors, whether SC or LC connectors are used for connection between network devices at data centres and for the connection of fibre optic cable to equipment on customer premises. SC and LC are two of the most commonly used connectors.

Connector 1

So what’s the difference and which one is better between the SC and LC cables?

SC Connectors
An SC connector or square connector, is a fibre-optic cable connector that uses a push-pull latching mechanism similar to that used in common audio/video cables, which makes it very easy to connect and disconnect the cables. A single cable is used for single-direction communication; so if a full duplex mode is required, two cables and two connectors are used in tandem.

Initially intended for Gigabit Ethernet networking, it was standardised into the telecommunications specification TIA-568-A in 1991 and slowly grew in popularity as manufacturing costs came down. Due to its excellent performance it dominated fibre optics for over a decade with only the ST competing with it.

LC Connectors
LC connectors or lucent connectors are examples of small form factor connectors and hold a single fibre in a 1.25 mm ceramic ferrule, half the size of the standard SC ferrule. Considered by some to be the modern replacement of the SC connector, the introduction of LC connector was less successful.

Having half the footprint of the SC connector gives it huge popularity in datacoms and other high-density patch applications, as its combination of small size and latch feature make it ideal for densely populated racks/panels.

So how do they differ?

Size
LC is half the size of SC, as the LC is just 1.25mm. One SC-adapter is exactly the same size as a duplex LC-adapter, therefore LC is more and more common in central offices where the number of connections per area is an important cost factor and efficiency.

Handling
SC is a true push-pull-connector and LC is a latched connector, although there are very innovative, real push-pull-LCs available which have the same handling capabilities like SC.

Age
The LC is the newest of the two connectors, SC is wider spread around the world but LC is catching up. Both connectors have the same insertion loss and return loss capabilities. Generally, it depends where in the network you want to use the connector, no matter SC or LC, even the other different kinds of connector.

Both SC and LC SFP transceivers are designed to achieve fast speed, high efficiency and security. All interconnected large complex databases must be able to receive and transmit data without external interference. You can choose whether LC SFP transceiver or SC SFP transceiver according to your needs.