Frequently Asked Questions (FAQ)

View below some frequently asked questions and our answers to them. Search on a topic. If you don’t see it covered, just asked our staff.

What is the difference between OM3 and OM4 fiber?

Both OM3 and OM4 fibers are laser optimized, high bandwidth multimode fibers. The standard color for these fiber cables is Aqua. OM4 fibers can carry more traffic than OM3 fibers because they have a higher bandwidth specification than OM3 fibers. Click here to read a Wikipedia article on the differences between multimode fibers.

What is the difference between a fiber optic connector with a PC, UPC , and APC polish?

This designation usually pertains to the return loss specification of the connector. Return loss is the amount of light being reflected back from the connector when it is joined to another connector. Light reflected backwards can interrupt the performance of a high speed laser. This is usually a problem with high speed single mode systems. Return loss is usually a negative number. For PC (Physical Contact) polish performance, the connector must not reflect back more than -40dB of light. For a UPC (Ultra Physical Contact) polish, the connector must not reflect back more than -55dB. For an APC (Angled Polish Connector) polish, the connector must not reflect back more than -65dB of light. Please note that APC connectors can only be mated to APC connectors.

What is the difference between PVC rated cable and Plenum rated cable?

PVC stands for Poly Vinyl Chloride and is commonly used to insulate cables. Unfortunately, when this cable burns from a fire, it emits poisonous and toxic fumes. Plenum cable is typically made with Teflon which does not burn as well and the fumes are not as toxic. Plenum rated cable is typically used in commercial buildings where the ceiling is used as an air return for HVAC systems. These plenum ceilings (where the return air is forced through the ceiling rather than being ducted through air conditioning tubes) have special requirements for cables running through them. Thus, plenum cable must be used in these kinds of situations in order to prevent toxic smoke from being pushed through the whole building in the event of a fire. Since plenum rated cables require higher cost materials to make them, plenum rated cables are typically more expensive than PVC rated cable.

What is furcation tubing?

Furcation tubing is used to beef up the diameter of the fibers protruding from the end of the cable. Many customers prefer ordering cables (micro-distribution) with fibers that have a simple thin 250um plastic coating or a thicker 900um “tight buffered” coating (distribution). While the sizes of these cables are relatively small, the problem becomes one of protection when the fibers emerge from these cables. The thin coatings (250um or 900um) are sometimes too flimsy for the abuse they will receive from installers and equipment during installation. In fact, 250um coated fibers must be “tubed” to at least a diameter of 900um for the connector to even be applied. And there are many customers who want their fibers to be “up-jacketed” to an even tougher covering of either 1.6mm, 2.0mm, or 3.0mm diameters. At these larger diameters, the tubing used typically has Kevlar inside the tube providing for much stronger pull strength, a key attribute when pulling cables through congested cable trays and conduit. Why not order cables with these larger coverings for each fiber (i.e. breakout cables)? You can, but large fiber count breakout cables are typically very very thick cables.

What is an MTP/MPO connector?

Most connectors (LC, SC, FC) have one fiber through them. The MTP/MPO connector has been designed as a “multi-fiber” connector (typically 12 fibers). The MPO connector and subsequent standard was developed in the late 1980’s by the NTT-AT corporation. The MTP by US Conec corporation soon came after that with some additional features like a removable housing, elliptically shaped alignment pins, and the ability to change the connector’s gender. The main thing to remember is that the MTP connector adheres to the MPO standard. Therefore, MTP and MPO connectors are interchangeable.

What are sub-units?

There are typically 12 colored fibers used to construct fiber optic cables. The 12 colors are standard and help installers connect fibers from cable-to-equipment or cable-to-cable. Sometimes, in order to make cables with more than 12 fibers, cable manufacturers will create a second set of 12 colored fibers using the same colors but adding a white dash mark or line along the length of the tight buffer coating. When fiber counts exceed 24 fibers, each of the 12 colored fibers are bundled into their own mini-jacket or sub-unit. The sub-units are then numbered so the installer can identify the blue coated fiber in Sub-Unit 1 versus the blue coated fiber in Sub-Unit 2 (and so on).

What are mini-boots?

Standard boots are typically about 1-1/2 inches long and can be used in most electronic cabinets. Sometimes the space between the electronics and the rear door of the cabinet is such that the door (when closed) will press against the fibers and cause transmission problems from the fiber being “bent”. Mini-booted cables have shorter boots (~3/4”) that may work better in these tight situations. Some customers also opt for angled boots or boots that can be “flexed”.

For copper assemblies – What do you mean by “Where is pin 1 in relation to the cable exit”

This is often asked when configuring a copper cable assembly with a 90 degree hood. Since most connectors are configured in a V shape the configuration depends on which side the installer wants to dress out the cable on. The cables in this situation are often referred to as “left feed”, “right feed” or “standard, “reversed”. Click below for graphical explanation.