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Comparison of UK-US Terminology

For the purpose of this guide US terminology is more frequently used.

                          UK                          

US

2-way lighting, switch

switch 3-way lighting, switch

cooker

range

distribution board

distribution panel, breaker panel

earth, earthing

ground, grounding

fitting

fixture

residual current device (RCD)

ground fault circuit interrupter (GFCI)

skirting board

baseboard

strapper

traveler

In general, the word energy refers to a concept that can be paraphrased as "the potential for causing changes", and therefore one can say that energy is the cause of any change. The most common definition of energy is the work that a certain force (gravitational, electromagnetic) can do.

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A transformer that converts a higher voltage current to a lower voltage current is called a “step down” transformer, and can work by either converting high voltage low current loads to low voltage high current loads, or by adding resistance between two circuts circuits to limit the voltage output, resulting in lower power being received on the output side.

A transformer that converts to a higher voltage is caleld called a “step up” transformer, and works by converting low voltage but high currents into high volutage voltage but low currents. A step up transformer does not add additional electricical electrical power to the circuit, it only increases overall voltage.

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The frequency is defined as number of sinusoidal oscillations per second:

  • 50 oscillations per second in Europe (50Hz),
  • 60 oscillations per second in the US (60Hz).

AC is the type of current supplied by electric utility companies because AC voltage can be increased and decreased with a transformer. This allows the power to be transported through power lines efficiently at high voltage and transformed to a lower, safer, voltage for use into businesses and residences. Therefore, it is the form of electrical energy that consumers typically use when they plug an appliance into a wall socket.

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There are two types of AC:

Single-phasePhase

A single-phase current is the most common type of current, and thus is usually the configuration delivered by public networks, but also by a single-phase generator. A single-phase AC current is supplied via two lines (phase and neutral), usually with a 220 V voltage difference between them. Plugs can be inserted in both ways.

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A single-phase load may be powered from a three-phase distribution transformer allowing single-phase lighting to be connected phase-to-neutral and three-phase motors to be connected to all three phases. This eliminates the need of a separate single-phase transformer.

Three-phasePhase

Once Power needs are increased, in the use of large electrical motor for example, constancy and balance pay a key role. Three-phase i s the common current configuration for electricity companies, and can also be produced with a three-phase generator. A three-phase current is the combination of three single phase currents.

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In every circuit there will be resistor(s) and generator(s), their number will the depend of the power requisites. Both components can be grouped depending on the what is required to keep constant, the current or the voltage. There are two basic ways to groups components in series or in parallel. (additional information in Connecting Batteries section)

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Series

The basic idea of a “series” connection is that components are connected end-to-end in a line to form a single path through which current can flow:

  1. Current: The amount of current is the same through any component in a series circuit.
  2. Resistance: The total resistance of any series circuit is equal to the sum of the individual resistances.
  3. Voltage: The supply voltage in a series circuit is equal to the sum of the individual voltage drops.

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Parallel

The basic idea of a “parallel” connection, on the other hand, is that all components are connected across each other’s leads. In a purely parallel circuit, there are never more than two sets of electrically common points, no matter how many components are connected. There are many paths for current flow, but only one voltage across all components:

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All of the aforementioned devices protect users and equipment from fault conditions in an electrical circuit by isolating the electrical supply. Fuses and MCBs only isolate the live feed; with RCDs and RCBOs isolate both the live and neutral feeds. It is essential that the appropriate circuit protection is installed ensure an electrical installation is safe.

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Fuses

A fuse is a very basic protection device used to protect the circuit from overcurrent. It consists of a metal strip that liquefies when the flow of current through it surpasses a pre-defined limit. Fuses are essential electrical devices, and there are different types of fuses available in the market today based on specific voltage and current ratings, application, response time, and breaking capacity.

The characteristics of fuses like time and current are selected to give sufficient protection without unnecessary disruption.

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Miniature Circuit Breaker (MCB)

An MCB is a modern alternative to fuses, and are maybe centrally located in buildings – usually called a “fuse box” or “braker box”, or attached to specific equipment. They are just like switches, turning off when an overload is detected in the circuit. The basic function of a circuit breaker is to stop the flow of current once a fault has occurred. The advantage of MCBs over fuses is that if they trip, they can be reset without having to replace the whole MCB. MCBs can also be calibrated more precisely than fuses, tripping at exact loads. Circuit breakers are available in different sizes from small devices to large switch gears which are used to protect low current circuits as well as high voltage circuits.

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Residual Current Device (RCD)

Residual Current Devices (or RCDs) are designed to detect and disconnect supply in the event of a small current imbalance between the Live and Neutral wires at a pre-defined value - typically 30mA. RCDs can detect when a live conductor touches an earthed equipment case, or when a live conductor is cut through; this type of fault is potentially dangerous and can result in electric shocks and fires.

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RCDs can be wired to protect a single or a number of circuits - the advantage of protecting individual circuits is that if one circuit trips, it will not shut down the whole building or distribution system, just the protected circuit.

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Residual Current Breaker with Overcurrent (RCBO)

An RCBO combines the functions of a MCB and an RCD in one unit. CRBOs are a safety device which detects a problem in the power supply and is capable of shutting off in 10-15 milliseconds.

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There are two ways to ground devices:-

  1. System or Service Ground: In this type of ground, a wire called "the neutral conductor" is grounded at the transformer, and again at the service entrance to the building. This is primarily designed to protect machines, tools, and insulation against damage.

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  1. Equipment Ground: This is intended to offer enhanced protection to the people themselves. If a malfunction causes the metal frame of a tool to become energized, the equipment ground provides another path for the current to flow through the tool to the ground.

A major precaution to grounding to be aware of: a break in the grounding system may occur without the user's knowledge. Using a ground-fault circuit interrupter (GFCI) is one way of overcoming grounding deficiencies.

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More than 3 mA

Painful shock- cause indirect accident

More than 10 mA

Muscle contraction – “No Let Go” danger

More than 30 mA

Lung paralysis, usually temporary

More than 50 mA

Ventricular fibrillation, usually fatal

100 mA to 4 A

Certain ventricular fibrillation, fatal

Over 4 A

Heart paralysis, severe burns

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Safety Equipment

To avoid or reduce the damaging effects current can have in a human body, is highly recommended to use protection equipment and take precautions when handling electrified circuits and equipment. 

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Part of avoiding an electrical fire includes properly sizing, using and maintaining the electricity system, however hazards can occur regardless and fire suppression tools should be in place. Fire extinguishers are the most reliable mean to do it, however the appropriate fire extinguisher must be used or the extinguisher itself may be ineffective.

Fire Extinguisher Classes Per Region:

American

European

UK

Australian/Asian

Fuel/

heat source

Heat Source

Class A

Class A

Class A

Class A

Ordinary combustibles

Class B

Class B

Class B

Class B

Flammable liquids

Class C

Class C

Class C

Flammable gases

Class C

Unclassified

Unclassified

Class E

Electrical equipment

Class D

Class D

Class D

Class D

Combustible metals

Class K

Class F

Class F

Class F

Kitchen Grade (Cooking oil or fat)

Electrical fires need to be put out by a substance that is non-conductive, unlike the water or foam found in class A fire extinguishers. If someone attempts to put out an electrical fire with something like water, there is a high risk of electrocution since water is conductive. This is why class C fire extinguishers exist; the substances that can be found in these types of extinguishers are monoammonium phosphate, potassium chloride, or potassium bicarbonate. Another option would be a class C extinguisher that contains carbon dioxide. CO2 is great for suppressing fires because it takes the fire’s oxygen source away as well as diminishes the fire’s heat since the CO2 is cold when expelled from the extinguisher.

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It is often possible to reduce electricity consumption without degrading the quality of service by improving the energy management, focusing on reducing the demand, and choosing the correct supply.

  • Energy demand management: minimize energy consumption without reducing quality of service and avoid unnecessary energy consumption.
  • Energy supply management: selecting the best main and back-up power supplies in accordance to the particular situation, properly sized to optimize investment and running costs.

To manage both demand and supply management, a proper diagnostic to understand the installation power and energy needs is required. Continued diagnostics it will be necessary at each step of the energy management process, mainly:

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Buying a generator may not be very expensive, but generators require fuel and maintenance and running costs can be quite high. Inversely, battery and solar systems require significant investments but will have very low running costs. Initial and running costs must be considered when choosing a power supply. As an example; (estimations)


Estimated Operating Costs:

Proposed

back

Back-up

Initial

cost

Cost

Total

cost after

Cost After 1

year

Year

Total

cost after

Cost After 2

years

Years

2kVA generator

600 €

14,600 €

28,800 €

Battery system

4,800 €

9,300 €

13,900 €

Solar (covering 30% of energy needs)

6,500 €

9,600 €

12,900 €

 

 

          Simulation of the global cost during 24 months (fuel price = 1€/L)

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Advantages

Disadvantages

Simple and cheap

Locally available

Limited nuisances


Short outages as the generator must be started when the grid go down

UPS and/or regulator necessary

Fuel supply and stock necessary

Maintenance required for the generator even if it is rarely used

Recommended for

-          Building connected to a public grid with long unpredictable outages

-          Building connected to a public electricity grid in a deteriorated security context

-          Building connected to a public electricity grid and used for a limited duration

-          Emergency back up when required

 

Generator + Generator

In a generator only configuration, electricity is provided by a two or more generators. For using two generators:

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Advantages

Disadvantages

Well-known technology

Locally available

Limited initial costs


Permanent noise and maintenance hassle

High running cost

Short outage as generators are switched

UPS and/or regulator required

Fuel supply and stock required

Limited reliability and frequent maintenance

Time consuming handling the system.

Recommended for

-          Isolated building with high energy needs

-          Isolated building used for a limited duration

-          Emergency back up when required

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Grid + Batteries

In this configuration, the main power supply is the electricity provided by a local power company, while the back-up is a battery system that provides a limited autonomy to the installation in case of outage.

Advantages

Disadvantages

24/7 electricity without outage and micro-outage

High reliability

Good electricity quality

Easy to add solar supply

No nuisances

Grid dependent

Local purchase and maintenance not always possible

Battery room required

Higher initial cost than a generator

Back-up generator may still be necessary

Limited lifespan of the batteries (2 to 5 years) and possible environmental impact of batteries disposal

Recommended for

-          Building connected to a public grid with short and frequent outages

-          Building connected to a public grid with night outages

-          First step towards Solar system installation

 

Generator + Batteries

In this configuration the main power supply is a generator that provides electricity during peak hours. The back-up is a battery system that accumulates electricity when the generator is running and supply the installation during low consumption hours. 

Advantages

Disadvantages

24/7 electricity without outage or micro-outage

No nuisance during low consumption hours (night…)

Good electricity quality

Better reliability and service-life of the generator

More flexibility on power consumption

Easy to add solar supply


Fuel supply and stock required

Minimum daily running duration for the generator to reload batteries

Local purchase and maintenance may not be possible

Battery room required

Higher initial cost than generator alone

Back-up generator may still be necessary

Limited lifespan of the batteries (2 to 5 years) and possible environmental impact of battery disposal


Recommended for

-          Isolated office or compound

-          First step towards Solar system installation

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Public Grid OR Generator + Solar

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The first thing to evaluate when looking for a generator is its size - how much power can it generate?

Power rating is standardized as ISO-8528-1, the most common standards are:

ISO Generator Rating

Load Rating

Run Time Limitations

Prime Rated Power (PRP)

Rated for a variable load

This power is available during unlimited hours of usage with variable load factor. An overload of 10% is possible during maximum 1 hour every 12 hours but not exceeding 25 hours per year.

Continuous Operation Power (COP)

Rated for a constant load

This power is available during unlimited hours of usage with a fixed load factor. No overload allowed.

Emergency Stand By Power (ESP)

Rated for a variable load

This power is available only during 25 hours per year with variable load factor. 80% of this power is available during 200 hours per year. No overload allowed.

Most of the time, only PRP is relevant when purchasing a generator. When acquiring a generator, check if the power of the generator is indicated without reference to a standardized rating method. If no rating model is indicated, either consult it with the manufacturer or obtain documentation from the seller.

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