A backbone is a term used to describe a main Internet link coming to a building, generally from a service provider. The principles used for bringing a backbone into the building to connect are quite similar, whether the backbone is coaxial cable, fibre optic, or wireless.

Please read the safety section for this module before proceeding with any work. Bringing in a backbone can present dangerous situations such as being on top of buildings, or high up on ladders.

Usually an exterior conduit is installed on buildings to bring wires in off poles, or to bring in lines from an installed wireless antenna. Less often, conduit may be at ground level, bringing the wiring directly into the building via conduit. Conduit is the most common method of bringing in a backbone, and there are some general principles to follow when bringing a backbone in.

The general principles for bringing a backbone into the building are as follows:

• Do not put any holes in the roof to bring wires in.
  
  • If bringing the line through the roof is desired, look for a location where wires already enter the building via the roof (generally found near HVAC - heating, ventilation and air conditioning systems). Here, there is usually a sealed lead conduit. This may be pryed open, and the desired new wires pushed into it. This is shown in the picture below. Be sure to squeeze the lead shut again once the new wires have been inserted, and seal it well with silicone when complete!

  
       

  Left: Gooseneck Ingress. Right: HVAC ingress - lead piping.
  
  

  • If bringing the line into the side of a building, try to use an existing hole, such as a ventilation hole, to bring the wires in. If no holes are available, drill the new hole through as closely as possible to where it needs to go in the building, and put the line straight in. If this means that wires must travel down the side of a building, ensure that they are very well secured to the building. This can be done using screwed-on tie-downs specialized for this purpose, and affixing the wires to them firmly with tie-straps. <show picture of secured ground line.>
    
  • Run a conduit up the side of the building to bring the cabling in. Most exterior conduit can be fit with proper "gooseneck" tops, which help to protect the cables coming in from weather.

  

  
  When pushing cable through these gooseneck tops:
  

  • Be careful not to exceed the bend radius of the cable being installed, particularily if it is fibre optic cable.
    
  • ensure that the cable is not pulled tight right up to the gooseneck. Instead, leave some slack called a "drip loop" - this ensures that water will run down and away from the cable going into the building, rather than straight down the cable into your network!

    
    

No matter what kind of backbone is installed, the main principles are to keep the network safe, and to keep the people and/or animals around the building where the network is installed safe.

• Ensure that cables are secured, protected, and out of reach.
  
• Ensure that cables are protected from wind and weather.
  
• Ensure that any holes in the building are WELL SEALED using silicone or similar sealant. This will keep out weather as well as bugs that may want to nest in the network.
  
• Be careful installing any cabling, and be careful when working at heights. Please read the safety section for this module before completing any installation.