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How to place OFC Joint Box in Manholes?

How to place OFC Joint Box in Manholes? : You all know that placing OFC joint box in manhole is not a special technical issue but from the point of view of O&M, this is a very technical and important issue. The purpose of writing the article " How to place OFC joint box" is that many technicians and site engineers do not follow the company's instructions due to which the O&M team has a lot of trouble or if the network has to be extended in the future, it becomes a huge bust.

Each telecom company has its own design but I will tell in this article that best way of how to place OFC Joint Box in Manholes. Maybe you all are considering this topic very lightly, but one mistake made in OFC project bothers you for a long time. Read this article till the end, you all will get to learn a lot.

OFC Joint Box in Manholes

OFC loop (Coil) in Manholes

During OFC Pulling, each manholes and HH have to keep a loop according to the company's instruction. This loop (coil) length can be up to 5–20 m. This is for the future purpose of OFC cut or for the easy splicing from outside of manhole / HH. 

This OFC loop (Coil) is also helpful in pulling the cable back and forth as per the requirement. If a manhole / HH does not have an OFC joint box, then it is sufficient to have only 5 meter loop. Many telecom companies prefer to keep only 3 meter loops. Remember, placing OFC loop (Coil) in manhole / HH is also very important.

Placing Of Joint Boxes in Manholes

When OFC splicing is done inside the manhole, a straight joint can be obtained by selecting a housing with cable inlets on either side. No additional cables should be placed on the manhole wall. The joint box is securely fitted into the cable brackets through a joint support. For better understanding, see the image below- 
Joint Box placing

In congested manholes, where splicing inside the manholes is not possible, it is advisable to perform splicing above ground. In such a case, in order to simplify the installation and handling of excess cable, a housing with inlets on one side should be used. The joint box and the cable slack can be clamped directly to the wall observing the minimum bending radius (i.e. 20 x out- side diameter of the cable).
Cable slack clamping on wall

Place the cable slack in a shape of loop behind the cable supports on both walls of the manholes. The joint is placed on cable racks as usual. Using this racking method creates a loop of slack at each joint location.

Should the fiber cable be cut between manholes, the slack can be pulled in the duct towards the break and repairs may be effected without having to replace the fiber optic cable section. 

Where a side to side cross over must be executed, the fiber cable entering the manhole must be racked over the first bracket nearest and equivalent in level. Raise or lower the fiber cable gradually until it becomes in line with the out duct. Employ cable roller and support for guidance of cable during pulling operation. The fiber cable should be fixed from the ceiling of the manhole by means of a steel rope to avoid sharp bends. Place the cable away from the manhole opening to avoid any hazards.

Cable Protection and Identification

Place the cable in such a way as to avoid rearrangements in the future. Crossing of cables should be avoided where ever possible. Place flexible protective sleeve over all fiber cables through the manholes tunnels and vaults, or any other location where the cable is exposed.

Use tie wraps or clamps of the proper size at all racks to hold the cable and flexible conduit from moving. Place fiber optic cable warning signs on the cable near all duct entrances and at intervals along the cable where it is exposed.

Last Word

I have tried my best to provide you complete information about how to place OFC Joint Box in Manholes , I hope you all liked the information given. This is also a special issue of OFC project about which this article has been written. If you like this article " How to place OFC Joint Box in Manholes ", then share it to others.

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