Last Updated: December 16, 2020

Kathleen Skelton
When it comes to fiber installations, cleanliness is the key to success.  Whether the work is in buildings, on construction sites or outdoors in trenches for fiber ducts, there is at a minimum, dust.  Dirty connectors cause the highest percentage of fiber optic network failures.  It might seem odd that dirt would rank above polishing errors, bad splices, broken connectors or excessive bends when talking about fiber failure but dirty end-faces do rank the highest.

Cisco had this information under their Inspection and Cleaning are Critical section ( that illustrates the delicacy of the situation:  “A 1-micrometer dust particle on a single-mode core can block up to 1% of the light (a 0.05dB loss). A 9-micrometer speck is still too small to see without a microscope, but it can completely block the fiber core. These contaminants can be more difficult to remove than dust particles. By comparison, a typical human hair is 50 to 75 micrometers in diameter, as much as eight times larger. So, even though dust might not be visible, it is still present in the air and can deposit onto the connector.”

In addition to failures due to the light loss, there is the possibility of equipment failure and the nightmare of unexpected costs for troubleshooting, replacing and fixing damages.

The International Electrotechnical Commission (IEC) created Standard 61300-3-35, which provides guidelines about the size and amount of dirt and contamination for single and multi-fiber end-faces and also specifies both the pass/fail requirements for endface quality and a process to verify the connector meets these requirements.

Visual inspection can reveal that there is potential trouble with dust or dirt but remember, many times this might not be visible.

There are solutions to ensure that clean fibers will provide clean connections. Very simply, in addition to using clean test cords and keeping them clean at all times, the step of cleaning connectors during the installation phase must become a mandatory part of the process.  Every company needs to have an approved cleaning procedure.

Prevention is that simple. Cleaning saves time and money.

FOC helpful tips on ensuring clean fiber connections include:

  • Following approved cleaning procedures is the first step in prevention
  • Clean connectors maximize the performance of the network and reduce repair cost

Fiber Optic Center is your resource to help answer your technical questions.  Email your questions to our AskFOC tool at   Our Technical Team will answer your questions.

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