Fiber Optic Questions from our Training Classes!

Our instructors get a lot of questions from students. We thought everyone could learn something by sharing! Here are a few…

Can a mechanical splice be used permanently?

Yes! They typically have a shelf life of 20+ years and an operating/storage temperature of –40°C to 75°C. However, the splice’s longevity and long-term performance are dramatically affected by the environment it’s installed in.

What is dB?

dB (Decibel) is a logarithmic way of expressing a power ratio. This unit of measurement is widely used in electronics and communication systems. Relative to fiber optic communications, it is used to express signal loss: the ratio of power in versus power out. For instance, a loss of 3 dB indicates that 50% of the optical power inserted at one end of a link is reaching the other end. A 0 dB loss represents 100% of the light reaching the far end — or no loss in a link.

What is a deadzone box?

A deadzone box is a length of fiber  — generally 100 meters to 2 km — used at the launch end of an OTDR to test a link. It can also be a launch cable, ring, or box. Deadzone boxes are used to view the first connector and first few meters of the link under test. Without a deadzone box, an OTDR cannot measure the front end of the link under test to accurately report loss and reflection at the first event.

Do you have a question that we can answer in a future newsletter?  Please send it to Rick Atchison at