Cable Termination is the connection of the wire or fiber to a device, such as equipment, panels or a wall outlet, which allows for connecting the cable to other cables or devices. The three main areas we will discuss are termination used in Telecom, Datacom and Fiber Optic industries. This involves the organizing of cables by destination, forming and dressing cables, and proper labeling as well as creating a connection with a copper or fiber conductor.
In order to begin, there is planning that must take place. Prepare for the termination by developing a strategy for the cable beginning and end, making sure you have the proper tools to complete the job. Remember the cable connection is not complete until all terminations are properly identified and labeled!
Making careful preparations before cable termination takes place will ensure that the job is done properly, and will save you time and money from the onset.
Begin by determining where the termination point is located. If unknown, make sure each cable will reach the farthest point in the wiring closet or equipment room. Next, route the cables to this area making sure the cable length is correct as well as labeling each cable as you go so you can identify it later. Then form and dress the cable by ensuring that all cables are parallel to each other, shaping them into neat bundles using hand tightened cable ties or hook & loop wraps. If a cable is too long, make sure to remark the newly created end the same as before. Once the termination area is set up, use the proper cable management hardware to act as the support and relief. This is important since some cables have specific minimum bend radius requirements. Knowing this will protect the integrity of the cable being installed.
Fault Finding in Electrical Wiring.
A typical electrical circuit consists of an electrical component (pump, light, motors, fan, etc.), any switches, relays, fuses, fusible links or circuit breakers related to that component, and the wiring and connectors which link the component to both the battery and the chassis (which is connected back to the battery to complete the circuit).
If you have the wiring diagram, fault finding is simplified, as you can identify multiple components included in the particular circuit. The possible fault can be narrowed down by noting if other components related to the circuit are operating properly. If several components or circuits fail simultaneously, the problem is likely to be related to a shared power/fuse or earth connection.
Electrical problems usually stem from simple causes, such as loose or corroded connections, a faulty earth connection, a blown fuse, a melted fusible link, faulty sensor or a faulty relay. Before testing the components of the electrical circuit, visually inspect the condition of all fuses, wires and connections in a problem circuit.
The basic tools for fault finding in electrical circuit is a basic Digital Volt Meter (DVOM) which will enable you to check for volt, amperage, continuity and resistance and a test light (for voltage drop and load test) . For more advanced faultfinding a scope can be used.
To find the source of an intermittent wiring fault a wiggle test can be performed on the wiring. This involves wiggling the wiring by hand to see if the fault occurs. Using this technique the fault can be narrowed down to the source of the fault to a particular section of the wiring. Intermittent wiring faults usually occurs due to poor or dirty connections, or a damaged wiring insulation, or internally broken wiring inside the insulation where movement is present (such as wiring going to trunk).
3 Phase Wiring
In a symmetric three-phase power supply system, three conductors each carry an alternating current of the same frequency and voltage amplitude relative to a common reference but with a phase difference of one third of a cycle between each. The common reference is usually connected to ground and often to a current-carrying conductor called the neutral. Due to the phase difference, the voltage on any conductor reaches its peak at one third of a cycle after one of the other conductors and one third of a cycle before the remaining conductor. This phase delay gives constant power transfer to a balanced linear load. It also makes it possible to produce a rotating magnetic field in an electric motor and generate other phase arrangements using transformers (for instance, a two phase system using a Scott-T transformer). The amplitude of the voltage difference between two phases is 3 times the amplitude of the voltage of the individual phases.
The symmetric three-phase systems described here are simply referred to as three-phase systems because, although it is possible to design and implement asymmetric three-phase power systems (i.e., with unequal voltages or phase shifts), they are not used in practice because they lack the most important advantages of symmetric systems.
In a three-phase system feeding a balanced and linear load, the sum of the instantaneous currents of the three conductors is zero. In other words, the current in each conductor is equal in magnitude to the sum of the currents in the other two, but with the opposite sign. The return path for the current in any phase conductor is the other two phase conductors.
As compared to a single-phase AC power supply that uses two conductors (phase and neutral), a three-phase supply with no neutral and the same phase-to-ground voltage and current capacity per phase can transmit three times as much power using just 1.5 times as many wires (i.e., three instead of two). Thus, the ratio of capacity to conductor material is doubled. The ratio of capacity to conductor material increases to 3:1 with an ungrounded three-phase and center-grounded single-phase system (or 2.25:1 if both employ grounds of the same gauge as the conductors).
Constant power transfer and cancelling phase currents would in theory be possible with any number (greater than one) of phases, maintaining the capacity-to-conductor material ratio that is twice that of single-phase power. However, two-phase power results in a less smooth (pulsating) torque in a generator or motor (making smooth power transfer a challenge), and more than three phases complicates infrastructure unnecessarily.
Three-phase systems may also have a fourth wire, particularly in low-voltage distribution. This is the neutral wire. The neutral allows three separate single-phase supplies to be provided at a constant voltage and is commonly used for supplying groups of domestic properties which are each single-phase loads. The connections are arranged so that, as far as possible in each group, equal power is drawn from each phase. Further up the distribution system, the currents are usually well balanced. Transformers may be wired in a way that they have a four-wire secondary but a three-wire primary while allowing unbalanced loads and the associated secondary-side neutral currents.
Three-phase supplies have properties that make them very desirable in electric power distribution systems:
- The phase currents tend to cancel out one another, summing to zero in the case of a linear balanced load. This makes it possible to reduce the size of the neutral conductor because it carries little or no current. With a balanced load, all the phase conductors carry the same current and so can be the same size.
- Power transfer into a linear balanced load is constant, which helps to reduce generator and motor vibrations.
- Three-phase systems can produce a rotating magnetic field with a specified direction and constant magnitude, which simplifies the design of electric motors, as no starting circuit is required.
Most household loads are single-phase. In North American residences, three-phase power might feed a multiple-unit apartment block, but the household loads are connected only as single phase. In lower-density areas, only a single phase might be used for distribution. Some high-power domestic appliances such as electric stoves and clothes dryers are powered by a split phase system at 240 volts or from two phases of a three phase system at 208 volts.
Singel Phase Wiring
If you’re not electrically minded, think of 1 (Single) phase power like a bicycle where only one leg (phase) is pushing on one pedal rotating around a crankshaft axis (neutral).
- Mechanically, power is calculated as leg pressure (Foot Pounds) times speed (Rotating Speed).
- Electrically, power is calculated as leg force (Voltage) times flow (Current).
Single Phase power is a two wire Alternating Current (AC) power circuit. Most people use it every day because it’s the most common household power circuit and powers their lights, TV, etc. Typically there’s one power wire and one neutral wire and power flows between the power wire (through the load) and the neutral wire.
- In the US, 120V is the standard single phase voltage with one 120V power wire and one neutral wire.
- In some countries, 230V is the standard single phase voltage with one 230V power wire and one neutral wire.
A home’s electrical panel — what electricians call a service panel but what most people know as their “breaker box”— serves as the switchboard for the entire house’s electrical system. The panel receives power from the utility company and distributes it to the individual circuits that supply all of the fixtures, outlets and other devices in the home. Learn the basics of electrical panel wiring; it’s a good first step to understanding your home’s electrical system and is essential to performing safe repairs and upgrades.
Types of Panels
It’s important to note that not all electrical panel wiring uses breakers, although that’s been the standard for over 50 years. The precursor to the breaker-type panel is the fuse panel, which uses disposable fuses (instead of breakers) to protect the circuits from shorts and overloads. To shut off the power to an individual circuit, you have to remove the fuse.
While most homes have a single service panel, or “main” panel, it’s not uncommon to have a secondary panel, called a subpanel, that is supplied by the main panel. A subpanel essentially is a small version of a main panel and may be installed when a main panel has no room left for adding circuits or to provide power (and easy panel access) to a house addition or new garage.
Behind your service panel door are the columns of circuit breaker switches, with the ON/OFF levers that you click over to the ON side whenever a breaker trips. The inner panel surrounding the switches conceals the guts of the electrical panel wiring.
Here’s what’s back there:
Three heavy-gauge service cables enter the panel from the electric meter. One of these is the neutral line, and it connects to the neutral bus bar — a metal strip with numerous screw terminals — inside the service panel. The two other lines are the hot lines. These connect to the two hot bus bars in the panel via a large “main” circuit breaker. Each hot line carries 120 volts of power.
A panel must also have a heavy grounding wire (usually bare copper) that connects to the neutral bus bar on one end and to a grounding rod driven into the ground on the other end. In houses with metal water pipes, there may also be a ground wire between the panel and a nearby cold-water pipe.
All of the remaining cables going into the panel are the individual circuit cables from the house (and subpanel, if you have one). The hot wire (usually black or red) from each cable connects to a circuit breaker, while the neutral wire (usually white) connects to the neutral bus bar.
Circuit breakers are the primary safety devices in your electrical system and they are integral to electrical panel wiring. A breaker automatically “trips” and shuts off power to a circuit if it senses an overload, which can be caused by plugging in too many appliances on one circuit, or by a short. A short can result from things like loose wires, damaged insulation or a curious kid sticking a coat hanger into an outlet (ouch).
Breakers are rated for the power draw of each circuit. Standard breakers carry 120 volts and either 15 or 20 amps (amperes). High-voltage breakers carry 240 volts and 30 or more amps. The amp rating is the number stamped on the end of each breaker switch lever. All panels should have an index label on the panel door listing the main devices on each circuit (e.g. “kitchen plugs,” “dryer,” “living room lights”).
Now that you know a little about electrical panel wiring, the most important rule to remember is: Always shut off the power to the area where you’ll be working. Before inspecting or removing a switch or other household device, for example, switch off the breaker serving the device’s circuit. And before doing anything with the panel — including removing the inner cover — shut off the main breaker. This cuts the power to all of the household circuits at once. However, the service cables and the points where they connect to the panel are always powered, so don’t go near them!
Advances in the design and quality of electrical components have made it possible for electrical systems to run for years without noticeable problems. While wonderful feats of engineering, well-designed electrical systems can lull building owners and operators into a false sense of security—right up until the moment the system fails. It’s for this reason, among others, that electrical maintenance is such an important part of commercial building operations.
What is Electrical Maintenance?
Electrical maintenance covers all aspects of testing, monitoring, fixing, and replacing elements of an electrical system. Usually performed by a licensed professional with a complete knowledge of the National Electric Code and local regulations, electrical maintenance covers areas as diverse as:
– Digital communication
– Electrical machines
– Lighting systems
– Surge protection
With an increased reliance on both data collection and machinery run by computer software, electrical maintenance is more vital than ever. The failure of a single component in the electrical system can cause extensive downtime or data loss.
Preventative Electrical Maintenance
Early identification of problems is a key aspect of electrical maintenance. For instance, should a back-up generator sit idle until needed, it may not start due to a number of factors. Old fuel clogging a fuel filter, uncharged starting batteries, or start switches left in the wrong mode can all prevent a smooth transition to backup power. These are basic problems, easily identified and addressed through preventative maintenance.
One of the major challenges to electrical maintenance is the nature of electrical wiring. It can be difficult to pinpoint the location of specific problems as the system is built into the building. Thermal imaging has become increasingly important in the industry for its ability to identify issues with both electrical connection points and equipment operation. By catching such problems early, electrical maintenance helps reduce unexpected power outages and protects equipment from damage.
What is electrical maintenance? It’s an aspect of building operations no commercial facility should be without. While large scale operations may have their own on-staff electricians, smaller facilities may find it more financially viable to contract with a licensed professional for scheduled electrical maintenance and servicing.
An electrician works on commercial, residential, agricultural and industrial projects. There is a direct relationship between the nature and quality of the product required and the payment made by the customer. Therefore the electrician has a continuing responsibility to work professionally in order to meet the requirements of the customer and thus maintain and grow the business. Electrical installation is closely associated with other parts of the construction industry, and with the many products that support it, normally for commercial purposes.
The electrician works internally, including the homes of customers and on small and major projects. He or she will plan and design, select and install, commission, test, report, maintain, fault find and repair systems to a high standard. Work organization and self-management, communication and interpersonal skills, problem solving, flexibility and a deep body of knowledge are the universal attributes of the outstanding electrician.
Whether the electrician is working alone or in a team the individual takes on a high level of personal responsibility and autonomy. From working to provide a safe and reliable electrical installation and maintenance service, in accordance with relevant standards, through to diagnosing malfunctions, programming and commissioning home and building automation systems, concentration, precision, accuracy and attention to detail every step in the process matters and mistakes are largely irreversible, costly and potentially life threatening.
With the international mobility of people the electrician faces rapidly expanding opportunities and challenges. For the talented electrician there are many commercial and international opportunities; however these carry with them the need to understand and work with diverse cultures and trends. The diversity of skills associated with electrical installations is therefore likely to expand.
A Substation receives electrical power from generating station via incomingtransmission line and delivers electrical power through feeders and this is used forcontrolling the power on different routes. Substations are integral part of a powersystem and form important part of transmission and distribution network of electrical power system.Their main functions are to receive energy transmitted at high voltage fromthe generating stations, reduce the voltage to a value appropriate for local distributionand provide facilities for switching some sub-station are simply switching stationsdifferent connections between various transmission lines are made, others areconverting sub-stations which either convert AC into DC or vice-versa or convertfrequency from higher to lower or vice-versa.The various circuits are joined together through these components to a bus-barat substation. Basically, Sub-station consists of power transformers, circuit breakers,relays, isolators, earthing switches, current transformers, voltage transformers,synchronous condensers/ Capacitor banks etc
Air Conditioning Installations and Service
Air conditioning (often referred to as AC, A/C, or air con) is the process of removing heat and moisture from the interior of an occupied space, to improve the comfort of occupants. Air conditioning can be used in both domestic and commercial environments. This process is most commonly used to achieve a more comfortable interior environment, typically for humans and animals; however, air conditioning is also used to cool/dehumidify rooms filled with heat-producing electronic devices, such as computer servers, power amplifiers, and even to display and store artwork.
Air conditioners often use a fan to distribute the conditioned air to an occupied space such as a building or a car to improve thermal comfort and indoor air quality. Electric refrigerant-based AC units range from small units that can cool a small bedroom, which can be carried by a single adult, to massive units installed on the roof of office towers that can cool an entire building. The cooling is typically achieved through a refrigeration cycle, but sometimes evaporation or free cooling is used. Air conditioning systems can also be made based on desiccants (chemicals which remove moisture from the air) and subterraneous pipes that can distribute the heated refrigerant to the ground for cooling.
In the most general sense, air conditioning can refer to any form of technology that modifies the condition of air (heating, cooling, (de-)humidification, cleaning, ventilation, or air movement). In common usage, though, “air conditioning” refers to systems which cool air. In construction, a complete system of heating, ventilation, and air conditioning is referred to as HVAC.
A Certificate of Compliance (COC) is a document that verifies that the electrical installations such as the plugs, lights, DBboard, geyser and wiring in a home comply with the legislated requirements as detailed in the Occupational Health and Safety Act.
“Prior to May last year, when these regulations were updated, a COC remained valid indefinitely and could be transferred with no limitations, unless changes were made to the electrical installations. This meant that sellers could merely provide the purchaser with the COC received when the seller originally bought the property, provided no changes were made,” explains Adrian Goslett, CEO of RE/MAX of Southern Africa.
To protect the buyer, a clause was often included in the Offer to Purchase, requiring a ‘current’ COC to be provided by the seller. The term ‘current’ as used in the Offer to Purchase often stipulated that the COC may not be older than three months, provided no changes had been made to the electrical installations during the previous three months. As such, the obligation to provide a ‘current’ COC was a contractual one stipulated in the Offer to Purchase, rather than a statutory obligation, since the law did not prescribe any timeframe.
“Last year the regulations in this regard were amended and now only an Electrical Certificate of Compliance (ECOC) issued within the last two years will be considered valid, provided no changes had been made to the electrical installations during this time. Thus, unless agreed to in the Offer to Purchase as a condition of sale, the buyer no longer has a right to demand a “current” ECOC and, if the buyer does insist thereon, it will be for the buyer’s account,” explains Goslett.
The new regulations also demand that the electrician issuing the ECOC must register with the relevant authorities annually, not once-off as was previously the case. “Sellers should therefore ensure that the electrician used is correctly registered with the Electrical Contracting Board of South Africa and the Department of Labour, by requesting to see the contractor’s registration card and accreditation certificate. This is particularly important in light of the fact that electricians no longer have to guarantee the electrical system is in working order, but only that it is safe, and the new requirement that a test certificate must accompany the ECOC,” says Goslett.
The conveyancer would obtain the original ECOC from the seller before registration. This means that the seller must get a certified electrician to inspect the electrical installations, if the ECOC in the seller’s possession is older than two years or if any changes had been made to the electrical installations during this time. An ECOC that is not older than two years, if no changes were made to the electrical installation during this time, is freely transferable. If any alterations or additions were made, the owner must obtain a certificate of compliance for at least the addition or alteration.
Since an ECOC cannot be amended, if the property is to be transferred to a new owner and any work has been done on the electrical system, a new ECOC must be issued at a cost of around R600 upwards, even if certificates of compliance for additions or alterations were obtained.
If any repairs are required before an ECOC can be issued, the seller would need to affect and pay for these repairs to obtain the ECOC.
Where a seller disagrees with a registered electrician regarding the compliance of the electrical system to the regulations, the seller can dispute the findings with the Chief Inspector.
The seller should not incur any significant costs if the electrical installation has been maintained and if a valid certificate of compliance for at least the additions or alterations was issued by any person who undertook electrical work at the premises. However, since many banks insist on a copy of the ECOC before a home loan is registered, and the conveyancer cannot proceed with the registration of the transfer without a valid ECOC, sellers should be aware that this issue can delay the transfer process.
“Purchasers on the other hand, should instruct the conveyancer to furnish them with the original ECOC after registration, since the legislation requires a property owner to be able to produce a valid certificate of compliance on request to an inspector,” he concludes.