Sooner or later a growing business needs the network in a second building. It might be a shop behind the office, a warehouse across the yard, or a new building on the same property. There are three ways to get it there: copper cable, fiber optic cable, or a wireless bridge. They are not equally good, and the cheapest one to install is often the most expensive to live with.
Why copper between buildings causes trouble
Running an ordinary network cable to the other building seems like the obvious choice. It has two problems.
The first is distance. Copper Ethernet is limited to 100 metres, and that includes the patch cords at each end. The cable route is always longer than the straight line between the buildings, because it has to go down a wall, through a trench or conduit, up the other side and across to the network equipment.
The second problem is electrical, and it is the more serious one. Separate buildings often have separate electrical services and separate grounding. The ground in one building is rarely at exactly the same voltage as the ground in the other. A copper cable joins the two, and current can flow along it. The result can be anything from intermittent errors to dead switch ports.
Lightning makes it worse. A strike does not need to hit the cable or the building. A nearby strike can induce a surge on a buried or overhead copper run, and that surge arrives at the equipment on both ends. Surge protectors that are properly bonded at each building reduce the risk, but they do not remove it.
Fiber is the default for a permanent link
Fiber carries light through glass instead of electricity through metal. That solves both copper problems at once. There is no electrical path between the buildings, so there are no ground loops and nothing for a lightning surge to travel along, provided the cable is an all-dielectric type with no metal in it. Armoured fiber cable does contain metal, and that armour has to be bonded correctly.
Distance stops being a concern. Multimode fiber carries 10 gigabit for a few hundred metres, and singlemode fiber carries it for many kilometres. For a new run between buildings, singlemode is often the better pick, because it places almost no limit on future speeds.
Fiber also ages well. To go faster later, you change the optics at each end and leave the cable alone. It is worth installing more strands than you need on day one, since the extra glass adds little to the cost and gives you spares.
The real cost of fiber is usually the pathway: trenching, conduit, or an aerial run. If there is already a conduit with space in it between the buildings, the job gets much simpler.
You may not need to pull new fiber
If fiber already exists on your property, do not assume a problem means replacing it end to end. Fiber can be joined by fusion splicing, where a machine aligns two glass strands and melts them together. A good splice loses only a tiny fraction of the signal, far less than a connector does.
That opens up some practical options. A cable that was cut by an excavator, crushed, or chewed by rodents can be repaired at the damaged spot, with the splices protected in a sealed enclosure. An existing run can be extended to reach a new building or a relocated network room. Damaged or dirty connectors can be replaced by splicing on new factory-made ends. Unused strands in an old cable can be terminated and put to work.
Testing tells you which of these applies. An instrument called an OTDR sends light down the fiber and shows where a break or bad joint is and how far away, and a light source and power meter confirm the total loss from end to end. Before accepting a quote to replace a fiber run, have it tested. The fault is often in one place.
Where a wireless bridge fits
A wireless bridge is a pair of directional radios, one on each building, pointed at each other. It is a legitimate option when a cable is impractical: across a public road, a paved lot you cannot cut, a waterway, a property you lease, or for a temporary site.
It needs a clear line of sight, and that has to stay clear. Trees grow, and a path that works in winter can fail when the leaves come out. Radios in the 5 GHz band reach further but share the airwaves with everyone else nearby. Radios in the 60 GHz band are very fast over short distances but lose signal in heavy rain, which matters in this part of the world.
A well-installed bridge on solid mounts with proper grounding can run reliably for years. It is still outdoor equipment that needs maintenance, and its speed is less predictable than fiber.
How to choose
- Permanent link and you can get a cable across: install fiber.
- Fiber already there but faulty or too short: test it, then repair or extend it by splicing.
- No way to dig or string a cable, or a short-term need: use a wireless bridge.
- Copper: only for short runs within one building's electrical system.
Uninexus does fiber fusion splicing, termination and testing in-house, and installs wireless bridges where they are the better fit. If you have two buildings to connect, or an old fiber run that has stopped working, send us a note describing the site and we can tell you what your options look like.