Low Voltage Wiring & Fiber Optic Cabling

Wiring is something often overlooked but forms the foundation of any network. There are many different types of cables of all sorts of scenarios. Knowing which one to use can be confusing but we know all the different options, ups and downs of every cable type. We also understand the importance of testing and labeling each line. Without testing its very hard to tell if the cable was installed properly other than it partially functions or not. A high end testing tool can tell you everything from what type of cable is being used to the pin out and the throughput. Without labeling performing any kind of work in the future is next to impossible as you will have to track down where each line goes.

Unshielded Twisted Pair (UTP)
Is the most commonly used type of copper cables that utilizes twists in the pairs to eliminate electromagnetic interference and crosstalk. Which is the signal on one wire jumping to another causing interference. Since there is less shielding the cables are cheaper but work fine in most environments.

Unshielded Twisted Pairs (UTP) Cable Unwrapped

Unshielded Twisted Pairs (UTP) Cable Unwrapped

Shielded Twisted Pair (STP)
Copper cables utilizing shielding and twists to eliminate electromagnetic interference and crosstalk. These cables are best suited for locations with high electromagnetic interference such as heavy industrial environments. These cables cost more but have a much higher performance rating of +10 gigabit and work in scenarios their unshielded cousins UTP just won’t.

Shielded Twisted Pairs (STP) Cable Unwrapped

Shielded Twisted Pairs (STP) Cable Unwrapped

Fiber Optic Cables
Fiber optic cables use light instead of electricity to send data down the cable. Because of this they are immune to electromagnetic interference and crosstalk. They are capable of much greater distances and come in two flavors multi-mode and single-mode. Both cables are capable of speeds of +100gbit but multi-mode is good for about 500 meters where as single-mode is capable of 10 to 200 kilometers without needing a repeater. Obviously single-mode is going to cost more but when going from building to building there really is no other option. Single-mode cables are run along the ocean floor to connect continents together and are absolutely vital in the operation of the internet. It is a common misconception that satellites provide these links. Satellites are too costly to launch and then impossible to upgrade as the technology advances. Multi-mode is generally used as up-link connections between switches and routers within the same building or buildings that are within 500 meters of one another. Fiber optic cables work by shooting a laser down a thin glass tube with an outer plastic shielding. Like UTP & STP they come in plenum or PVC however they also can be made armored protecting the strands from being cracked by stretching or turning to abruptly which would cause the light to travel back the way it came referred to as refraction. Fiber optic cables often contain many strands anywhere from 1 to 864 each acting independently of one another. When running fiber optic cables it makes much more sense to have extra strands for expansion because running these cables can be extremely costly and running a cable with 1 strand costs practically the same as running a cable with 864. The cable its self will cost more for each additional strand but compared to the costs of running it dwarfs that of the cable. So especially when running along the ocean floor you’re going to want the maximum number of strands. Each strand can be leased to another company as their own individual line allowing for more profits from a single cable. There’s also a technology called Dense Wavelength Division Multiplexing (DWDM) which allows for several different wavelengths of light to be sent down a single strand. Now a single strand can carry several 100gbit signals making their capacity near limitless. Now for companies that cant afford to lease their own strand can lease a unique wavelength on a shared strand giving the operator of the cable additional revenue streams or the ability to add bandwidth capacity to existing cables that already have all the strands in use. Now to connect two fiber optic cables together or putting an end connector on requires a special tool called a plasma fusion splicer. Which actually heats then fuses the two pieces of glass together that has very low tolerances so it is important that it’s done perfectly. This is why these tools are so expensive ranging from $2000 to $50,000 and require a tester which in some cases is built in to the fusion splicer to certify the connection is done properly. The more expensive splicers can actually fuse multiple strands at once which can save a lot of time when dealing with an 864 strand cable.

Structure of a Fiber Optic Cable Diagram

Structure of a Fiber Optic Cable Diagram

Multi Stranded Fiber Optic Cable

Multi Stranded Fiber Optic Cable

Cable Management
Cable management can be crucial especially in large networks. Being able to diagnose, find and replace cables can be a daunting task in some networks. A network with proper cable management promotes, labeling, better air flow, cable trays, velcro / zip-ties, easier management and maintenance. Not to mention it just looks better and more professional.

Bad vs Good Cable Management

Bad vs Good Cable Management

Transceivers
Most commonly referred to as the small form-factor pluggable (SFP) which is a compact, hot-pluggable network interface module. That allows for a single switch, router or network interface card to support several different cable types depending on the application. As stated above there are lots of cable types each having their own unique properties. By using transceivers each port can use the cable type that best suits the requirements of its use. Making the devices much more agile and able to adapt to all the scenarios so that you don’t need a new device every time your cable requirements change. Which will save money and increase the lifetime of the device. Most device manufactures including Cisco, Juniper and Brocade offer their own transceivers that a very expensive but covered by their support warranty. However other manufacturers make generic models that are essentially the same except much cheaper but that wont be supported by the device warranty. Keep in mind you need a transceiver for each port on either end of the cable. So this can add up quickly to the overall cost of the equipment but they’re only needed for the ports in use. They also help increase the lifetime of the device because when one fails the transceiver can just be replaced instead of the entire device.

Various SFP Transceivers

Various SFP Transceivers

Patch Panels
A patch panel is used to go from riser cable with a solid core to a patch cable that has a stranded core. With the other end going to the keystone jack and the patch cable plugging in to a switch. It is also used to label and organize all the wires. This needs to be placed in an equipment rack or mounted to the wall so it doesn’t move. Each wire needs be connected to the patch panel using a punch down tool. This needs to be done correctly maintaining the twists in the cable or you risk near end crosstalk which will create errors and adversely affect the performance.

RJ-45 Wiring Patch Panel

RJ-45 Wiring Patch Panel

Keystone Jacks
This is a standardized form of jack and face plate combination so you can have a single face plate that through a modular design allows several types wires hook up to it.

Various Keystone Jacks

Various Keystone Jacks

PVC vs Plenum Cables
There are two choices of material that wraps around the wires PVC and Plenum. PVC is cheaper but releases noxious gases when burned. Where as plenum does not release any gases and is rated for open air pathways. Plenum can be mandated by the building code depending on where you are located but is far more expensive that PVC.

PVC vs Plenum Cable Jacket

PVC vs Plenum Cable Jacket

PVC vs Plenum Cable Pathways Diagram

PVC vs Plenum Cable Pathways Diagram

Power Management & Equipment Racks

A rack is really a necessity when dealing with even a small amount of servers and networking gear. The rack gives something to mount all the equipment to preventing it from getting knocked over or moved in any way. The rack can also be mounted to the floor or the wall so that it cant be moved either. A rack can come fully enclosed with a locking mechanism to keep out unauthorized users from touching and in some cases even seeing the equipment. This is especially prevalent at data centers because this is how space is sold and separation of one client from another.

48u Full APC Enclosed Equipment Rack

48u Full APC Enclosed Equipment Rack

Rack Unit (U)
This is a standardized form of measurement used on equipment racks that equals 1.75 inches. When purchasing a rack or any rack mountable equipment the size of the device will be measured in “U”s. A full rack is between 42u-48u and a half rack is 22u-24u.

Rack Units (Us) Diagram

Rack Units (Us) Diagram

110/120 Volt AC  vs.  220/240 Volt AC  vs.  48 Volt DC Power Feeds
All business grade IT equipment will run at 110/120 volt AC and 220/240 volt AC. When possible we want to run  a higher voltage such as 220 or 240 volt AC. The reason being it is more efficient so 20 amps of 220 volt AC is the same as 40 amps of 110 volt AC. The higher voltage is also more efficient so you will use less overall power at the higher voltage. Finally there is 48 volt DC which is by far the most efficient and will use least amount of overall power. The reason being there’s no ac to dc conversion since all electronic equipment runs on DC or direct current there’s no loss associated with the conversion. The downside is most data centers don’t offer this and all of your networking gear has to have 48 volt DC power supplies. These power supplies are cheaper since there’s no conversion happening however since less are made they are harder to find and sometimes more expensive just due to the fewer numbers manufactured.

Power Distribution Units (PDU)
A power distribution unit is a device fitted with multiple outputs designed to distribute electric power, especially to racks of computers and networking equipment located within a data center. Data centers face challenges in power protection and management solutions. Advanced forms of PDUs referred to a switched PDUs will let you log in to them remotely that displays the power usage of every port including the totals and allows you to power cycle individual ports turning the power off and on. APC makes a zero U PDU that mounts to slots in the back of the rack so as not to take up any additional space in the rack its self allowing for the maximum amount of servers and switches. They are made in 110/120 volt AC  and 220/240 volt AC models with a variety of outlets.

Various Power Distribution Units (PDUs)

Various Power Distribution Units (PDUs)

Uninterruptible Power Supplies (UPS)
Provides power to equipment in the event of an outage utilizing an array of batteries. Also provides power conditioning which protects against over and under voltage power events. Each UPS is rated for a certain amount of wattage that determines the load the UPS can handle and how long the batteries can sustain said load. Most UPSs at maximum load will only last for 15 minutes on battery power. To increase this time you can purchase batter extenders or larger UPSs with a higher wattage rating. Manufactured in 110/120 volt AC and 220/240 volt AC models. With step down transformers for going from 220/240 volt AC to 110/120 volt AC.

Uninterruptible Power Supply (UPS) Diagram

Uninterruptible Power Supply (UPS) Diagram

Automatic Transfer Switches (ATS)
Automatically switches between two or more power feeds such as a generator, backup batteries or a second utility circuit / grid keeping equipment powered on in the event of an outage, failure of equipment or a circuit. Made in all shapes and sizes ranging from 110 volts to 1000s of volts and 20 amps to 1000s of amps.

Automatic Transfer Switch (ATS)

Automatic Transfer Switch (ATS)