Wiring For Light And Power

1. Introduction

The Trinidad and Tobago Electricity Commission has set out in this booklet its requirements for Consumer’s Installations and equipment.

This booklet only covers general requirements. Consumers and other interested parties are therefore advised to seek additional guidance and information from the Commission when planning or modifying installations, or purchasing equipment, appliances or other apparatus for which the Commission would be requested to supply electrical energy. In this regard particular attention should be paid to Section 6 below.


2. Definitions

2.1 Commission means the Trinidad and Tobago Electricity Commission.

2.2 Consumer means any person supplied with energy by the commission.

2.3 Main means any electric line which may be laid down or erected by the Commission through which energy may be supplied or is intended to be supplied by the Commission.

2.4 Service Line means any electric line through which energy may be supplied or is intended to be supplied by the Commission to a Consumer either from any Main or directly from the premises of the Commission.

2.5 Installation  means all the electrical wiring and equipment fed from one service line supplying energy to one or more consumers and owned by the Consumer/s or landlord.

2.6 Point of Supply  / Point of Entrance   means the point at which the Commission supplies energy to an Installation serving one or more Consumers.

2.7 Entrance Cable means that portion of the installation between the point of Supply and the meter, and made up in the form of a cable.

2.8 Consumer’s Terminals means the ends of the electric lines belonging to the Consumer at which the supply of energy is delivered from the entrance cable

For a low voltage Installation, the Consumer’s Terminals shall be on the load side of the meter.

For a high voltage Installation, the Consumer’s Terminals shall be on the line side of the meter.


3. Characteristics of Supply

3.1 The Commission supplies only single and three phase alternating current sixty hertz (cycle per second) energy with the following declared voltages and characteristics:

(a) Single phase, 2 wire, 115 volts used for installations with loads up to a maximum of 30 amperes.

(b) Single phase, 3 wire, 115/230 volts for installations with loads up to a maximum of 200 amperes.

(c) Three phase, 4 wire, 115/230 volts from a delta-connected source for installations with combined lighting and power loads up to maximum demand of 199 KVA. Voltage of 230 across phase wires, 115 between either of two phase wires and earthed neutral, and 200 volts between this third phase wire and neutral. (This third 200 volt phase wire must be positively identified with the colour blue throughout the Installation or by whatever means of identification is required by the codes in force.)

(d) Three phase, 4 wire, 230/400 volts from a star-connected source for installation with combined lighting and power loads up to maximum of 350 KVA.

(e) One of the following high voltages depending on the maximum demand of the load, location of the installation and the voltage available at that location:

3 phase 3 wire 6.6 kV
3 phase 3 or 4 wire 12 kV
3 phase 3 wire 33 kV
3 phase 3 wire 66 kV
3 phase 3 wire 132 kV

Accordingly, it is important that the consumer consult the Commission before making plans for an installation to be supplied at high voltage.

3.2 Consumers requiring supplies with utilization voltages other than the Commission’s standard voltages declared in 3.1 (a), (b), (c), (d), and (e) above shall be supplied at one of the Commission’s standard high voltages declared in 3.1 (e) and are required to provide their own transformers.

3.3 The Commission shall supply a Consumer or a multiple occupied premise with only one of the voltages mentioned in 3.1 (a), (b), (c), (d) and (e).

3.4 The Commission reserves the right to change its system and its methods of distribution form time to time within the limits of the Trinidad and Tobago Electricity Commission Act Chapter 54.70 if it considers it advisable for an economical and more efficient supply to the public. Where such changes involve alteration to the Consumer’s installation and equipment the Commission will normally make the changes at its own expense.

3.5 The Electricity Supply Rules made under Section 15 of the Electricity (Inspection) Act Chapter 54.72 provides for variations of six percent above or below the declared voltages.


4. Application for Supply

4.1 Application for supply should be made well in advance of the date the supply is required. Such “Request for Supply” can be made at any of the Commission’s offices listed in the Contact Us section.

4.2 Consumers are advised not to commit themselves to the wiring of their premises before their “Request for Supply” has been considered by the Commission. This is essential if their premises are located more than 30.5m from the low voltage distribution mains of the commission and more so if the request is for 3 phase or high voltage supplies.

4.3 In all cases requiring mains extensions, the Consumer will be required to grant the Commission all the necessary easements for the construction of such mains as well as any extension thereof to supply other consumers. Such mains with associated equipment shall be and will remain the property of the Commission to operate, maintain and to be utilized as the Commission may decide.

4.4 A Consumer requiring a supply for a period less than 12 months shall be required to pay the full cost of installing and removing all mains and equipment required to provide such a supply together with a percentage of the cost of the reusable materials as determined by the Commission. THIS TOTAL PAYMENT SHALL BE MADE IN ADVANCE.

Charges for energy consumed shall be in accordance with the Commission’s standard tariffs and the Consumer may be required to deposit payment in advance for anticipated energy consumed for a period to be determined by the Commission.


5. Change in Consumer’s Requirements

5.1 The capacity of the system provided by the Commission is designed to guarantee an adequate supply to the Consumer’s Installation for the load requested. Any appreciable increase in load therefore could result in disruption of the supply or damage to equipment. The Consumer is therefore required to give reasonable notice to the Commission of any intention to increase the demand on the system so that adequate facilities could be provided by the commission on its system.

5.2 The Consumer is liable for the cost of repairing any of the Commission’s equipment which is damaged because of the failure of the Consumer to comply with the requirements of (5.1) above.


6. Inspection of Consumer Installation

6.1 The Consumer ‘s Installation shall conform to the appropriate regulations of the Electric Installations (Buildings) Act Chapter 54.71 and other rules or regulations having the force of statue and of any modification applicable to the taking and/or use of electricity within the Consumer’s premises.

Before any Installation can be connected to its system, the Commission shall be presented with an Inspection Certificate of Approval for the Installation. This Certificate is to be obtained from the Chief Electrical Inspector, Electrical Inspectorate Division

6.2 The Commission reserves the right to withhold or discontinue its supply whenever it considers that any Installation is likely to affect the quality of the supply to other Consumers and the Chief Electrical Inspector shall be notified.

6.3 The Commission can inspect an Installation for purposes related to the supply of electricity and can refuse to supply an Installation if it does not meet the requirements of the Commission and or the Chief Electrical Inspector.

6.4 An electrical Installation which has been disconnected from the Commission’s system for a period of more than three months shall be re-inspected and approved by the Chief Electrical Inspector before the Commission will connect hat installation to its system.

6.5 The Commission shall not be responsible for damage resulting from defects in the Consumer’s Installation. The Consumer is advised to obtain the services of a Licensed Electrical Wireman to repair the Installation and obtain an Inspection Certificate of Approval for the work undertaken by the Licensed Electrical Wireman. A defective Installation disconnected from the system by the Commission shall not be reconnected until the Inspection Certificate of Approval has been presented to the Commission.


7. Point of Supply

7.1 The Consumer or his representative is advised to consult the Commission to determine the location of the Point of Supply for a new Installation or an Installation which is to be modified

7.2 The Point of Supply for an Installation supplied at 115/230 or 230/400 volts shall be the Consumer’s Terminals which connect with the Commission’s Service Line and should be located on or near the face of the building nearest to the Commission ‘s distribution pole on which the appropriate voltage supply is available, except in the case where the appropriate voltage supply is available, except in the case where the Consumer provides an underground Entrance Cable.

7.3 In the case where it is necessary for the Commission to install transformers on the Consumer’s premises to supply the Consumer at 15/230 or 230/400 volts the secondary terminals of the transformers shall be the Point of Supply.

7.4 The Point of Supply for a Consumer’s installation supplied at high voltage shall be either the Consumer’s Terminals which connect with the Service Line or the Terminals of the Commission’s disconnecting means or such other point as negotiated between the Consumer and the Commission.


8. Service Line

8.1 The Commission shall provide only one Service Line to supply a building which shall be considered as any structure under one roof.

8.2 The Commission shall install an overhead Service Line to connect to the Point of Supply as indicated in Figure 1.

TRINIDAD AND TOBAGO ELECTRICITY COMMISSIONfig1

 TYPICAL OVERHEAD SERVICE LINE

WITH CONSUMER’S ENTRANCE CABLE ON

CONSUMER’S BUILDING

FIGURE 1

8.3 The overhead line service conductors shall be connected at a minimum height of 3.7 meters above finished grade level or at such greater height as it is necessary to maintain a minimum height of 6.1 meters for clearance of the Commission’s overhead Service Line over roads.

8.4 In order to meet the clearance requirements in 8.3 above or any other requirements the Consumer shall where necessary provide and maintain in accordance with the Commission’s specification a structure on the building or intermediate supporting structure’s on the premises to support the Commission’s overhead Service Line.

8.5 The Commission does not under normal circumstances provide underground Service Lines. Consumers can however provide underground Entrance Cables as part of their installations to locations specified by the Commission. It is preferred that for 115/230 and 230/400 volts installations the Consumer’s Terminals at the Point of Supply be located at a pole furnished and maintained by the Consumer on his premises at a location at the boundary of his property and nearest to the Commission’s distribution pole as indicated in Figure. 2.

 TRINIDAD AND TOBAGO ELECTRICITY COMMISSIONfig2

TYPICAL OVERHEAD SERVICE LINE

WITH CONSUMER’S ENTRANCE ON

CONSUMER’S PRIVATE POLE

FIGURE 2

 


9. Consumer’s Entrance Cable

9.1 The Commission shall connect only to a single Consumer’s Entrance Cable at the Point of Supply to a building.

9.2 Consumer’s Entrance Cable shall be in either rigid metallic conduit treated against corrosion or other approved non-corrosive enclosures or shall be concentric or tamperproof cable from the Consumer’s Terminals at the Point of Supply to the metering equipment and should preferably continue to the Consumer’s main switch. If conduit is used, only standard conduit elbows and fitting to facilitate pulling of the cable shall be allowed. Splicing of consumer’s entrance Cable shall not be permitted.

9.3 An approved weather had or gland is required at the Consumer’s Terminals at the Point of Supply and a minimum of 0.5 meters of cable must be left for connection to the Commission’s Overhead Service Line. Attachment to the Commission’s conductors shall be made a point no less than 0.3 meters from the weather head.

The Consumer is required to provide and install terminating lugs for connecting to cables with conductor sizes larger than 95mm2.

9.4 Multiple occupancy buildings with accommodation for two or more Consumers shall not be supplied unless the Entrance Cable is adequate to supply the entire number of Consumers.

9.5 The size of a Consumer’s Entrance Cable for a building with two or more metered Installations supplied at 115/230 or 230/400 volts shall not be less than 16 sq. mm. This cable size is for copper conductors, rubber, polythene or PVC insulated. Other approved cables can be used with equivalent current carrying capacities.


10. Meters

10.1 In general all electrical energy supplied to a Consumer at a single location shall be metered by a single meter.

10.2 The Commission shall furnish, install, connect and maintain meter(s) required for the measurement of electrical energy and maximum demand for billing purposes. These meters shall remain the property of the Commission.

10.3 Outdoor meters sockets shall be supplied by the Consumer and shall conform with the American National Standard Institute’s Standard ANSI C12.7 for watt hour meter sockets.

10.4 Outdoor socket type meters shall be installed for single phase 115/230 volts Installations up to a maximum of 200 amperes. The Consumer shall furnish and install the Entrance Cable and meter socket. Meter sockets of the ringless type are acceptable but must be provided with an approved means for sealing the cover.

Consumers should obtain advice with respect to the selections of either the 100 or 200 ampere meter sockets for their Installations.

10.5 Meter Sockets shall be installed on an outer wall of the premises. Meters whether installed indoor or outdoor, shall not be located over doorways, along stairways or directly under water pipes or drainpipes and shall be mounted free form shock, vibration and mechanical injury.

10.6 In a building elevated more than 2.4 metres above ground the meter shall be located on one of the supporting columns of the building.

10.7 Meters shall be accessible for reading and testing at all times and located so that the tops of the meters are not over 1.8 metres of less than 1.5 metres above floor or finished grade. A clear space of at least 0.9 metres in front of all meters must be available at all times.

10.8 Where the Commission decides to install an indoor type meter the Consumer shall provide a meter-board for mounting the meter. Meter-boards shall be sized for the Consumer’s Tariff, as shown in fig. 3 and shall be made form 19 mm hardwood stock free from knots set plumb and level and securely fastened to substantial supports.

Click on the relevant figures below to see details

fig3

FIGURE 3

10.9 Meters for a residential/commercial multi-storey and multi-occupancy building shall be grouped in one location on either the basement or ground floor in an accessible location. Where there are more than six metered Installations in the building, the Commission shall permit the installation of groups of not less then six meters on the basement floor, the ground floor and accessible locations on any of the upper floors. Each meter circuit must be positively identified with the Installation to which it is connected.

10.10 The Commission shall provide outdoor socket type class 200 meters for all new 115/230 and 230/400 volts, three phase Installations with loads of up to 200 amperes per phase for Consumers. Consumers shall, therefore, be required to provide ringless type outdoor 200 ampere, 7 jaw meter sockets for such Installations. The Consumer may consider it an advantage to install a meter socket with by-pass facilities, since this would enable meter testing without disruption of supply.

10.11 Three phase, 115/230 volts and 230/400 volts Installations loads up to maximum of 200 amperes per phase shall be metered by whole current or self-contained socket type meter. For loads between 201 and 500 amperes per phase current transformer metering shall be provided by the Commission. The Consumer shall furnish and install the current transformer cabinet and meter-board (see fig. 3) and meter cabinet where necessary. The meter cabinet shall be sized to accommodate the appropriate meter board shown in fig. 3 and shall have a minimum depth of 25.4 cm.

Between the Current Transformer Cabinet and the meter board of the meter cabinet a 20 mm conduit properly terminated and bushed containing three 1.5mm2 identified red, white, blue and four 2.5mm2 identified red, white, blue and black 600 volts insulated conductors must also be provided and installed by the Consumer.

The conductors between the current transformers and meter should not be more than 15m in length. Lengths of not less than 0.9 metres must be provided outside the two ends of the conduit to permit connection to the Meter and the Current Transformers by the Commission as indicated in fig. 3. The Consumer or his Contractor shall obtain the Current Transformers from the Commission and install them in a Cabinet on the supply side of the Main Switch.

10.12 Three phase, 115/230 volts and 230/400 volts Installations requiring loads in excess of 500 amperes per phase shall be supplied and metered at high voltage by the Commission. The metering unit shall be installed by the Commission on a Distribution Pole supplied by the Commission or the Consumer, or in the Consumer’s Transformer Substation subject to the conditions of the supply.

10.13 A Consumer shall at his own expense provide a new and approved location for the meter whenever the meter becomes inaccessible for reading and testing by reason of any building or other changes made by the owner or occupant.

10.14 Only authorized employees of the Commission and Government Electrical Inspectors are permitted to break meter seals to carry out inspection or testing of the meter and/or installation. All other persons are forbidden to interfere with metering and associated equipment.

10.15 The Commission shall not permit pilot lights, voltmeters, ammeters or any Consumer’s equipment to be connected to the secondaries of its metering transformers or associated metering equipment.


11. Consumer’s Installation

fig5

11.1 A Consumer shall furnish, install and maintain all wiring, equipment, and apparatus, except the meter/s, connected with his Installation from the Point of Supply

11.2 Any accessible part of the Consumer’s Installation between the Point of Supply and the load side of the metering equipment shall be sealed by the Commission. The Consumer shall provide the means by which the Commission can apply its seals.

11.3 All equipment furnished by the Commission and installed in the Consumer’s premises shall always remain the property of the Commission and may be removed therefrom either for servicing or when no longer required for the particular Installation.

11.4 The portion of the Consumer’s Installation between the Point of Supply and Main Distribution Panel shall be subject to the approval of the Commission in addition to the normal approval of all other authorities having jurisdiction.

11.5 The minimum sizes of Main Switches or Circuit Breakers permitted on Consumers’ Installations are as follows:-

Characteristic of Supply Minimum Current Rating of Main Switch
115 volts, 2 wire, 1 phase 30 amperes
115/230 volts, 3 wire, 1 phase 60 amperes
115/230 volts, 4 wire, 3 phase 60 amperes
115/400 volts, 4 wire, 3 phase 60 amperes

11.6 In building with more than one separately metered Consumer’s Installation a metal splitter box with a suitably sized Circuit Breaker for each Installation shall be installed between the Consumer’s Entrance Cable and the meter socket s by the Consumer/s or Landlord. Provision shall be made on the splitter box for the Commission to apply its seals or locks. Each Circuit Breaker in the splitter box shall be suitably identified with the Consumer’s Installation connected to it.

11.7 Where there are seven or more separately metered Consumers’ Installation in a building, a main disconnecting means or Circuit Breaker shall be installed between the Consumers Entrance Cables and the group of Circuit Breakers in the splitter box by the Consumer/s or Landlord. Provision shall be made for sealing or locking of this switch or breaker by the Commission.

11.8 Where a Consumer requires a supply in a building already wired with one or more metered Installation, he should consult the Commission before any work is done. In all such cases adequately sized Entrance Cable and splitter facilities shall be provided by the Consumer.

11.9 Where the Commission considers it necessary to install Transformers and associated equipment on a Consumer’s premises to supply the Consumer, the Consumer shall furnish, construct and maintain an enclosure according to the Commission’s specification and without charge to the Commission.

11.10 The Commission shall not provide a supply at high voltage to any Consumer unless the Consumer guarantees in writing that every portion of the Consumer’s Installation which is for use at high voltage will be maintained in a safe and efficient state to the satisfaction of the Commission and an authorized person will be available at all reasonable times for switching.

11.11 The Consumer shall furnish and install a high voltage Circuit Breaker as the primary disconnecting means for an Installation with a maximum demand in excess of 800 KVA. The Consumer should conform with the Commission’s Specification with respect to the rating and rupturing capacity of the Circuit Breaker. The limits of the Consumer’s protection setting shall be stipulated by the Commission to ensure discrimination with the protection of the Commission’s system.

It is recommended that the Consumer maintain an adequate supply of spare parts for the normal maintenance of his circuit breaker and ancillary apparatus.

11.12 Figs. 4 to 9 show examples of typical Installations and locations of the Service Line, point of Supply, Entrance Cable and Consumer’s Terminals. In all cases, maintenance of all wiring, equipment and apparatus in the Installation is the responsibility of the Consumer/s and/or landlord and not of the Commission.

fig4

TYPICAL INSTALLATION

Single Metered Low Voltage Supply

FIGURE 4

fig5

TYPICAL INSTALLATION

Multi-Metered Low Voltage Supply (6 meters or less)

FIGURE 5

fig6

TYPICAL INSTALLATION

Multi-Metered Low Voltage Supply (7 or more meters)

FIGURE 6

fig7

TYPICAL INSTALLATION

Single Metered High Voltage Supply

FIGURE 7

fig8

 

TYPICAL INSTALLATION

High Voltage Supply with Multiple Low Voltage Metering( 6 meters or less)

FIGURE 8

fig9

TYPICAL INSTALLATION

High Voltage Supply with Multiple Low Voltage Metering( 7 or more meters)

FIGURE 9


12. Motors And Miscellaneous Apparatus

12.1 The starting current of motors and inrush current of other apparatus such as welders and X-ray machines shall be such as not to impair the quality of supply rendered by the Commission to Consumers.

12.2 Motors up to 750 watts in size can be supplied at either 115 or 230 volts, single phase

12.3 Motors of over 750 watts and up to 5,600 watts in size can be supplied at 230 volts either single or 3 phase depending on the supply available in the district except that single phase motors rated between 3,750 and 5,600 watts shall be arranged for no load starting.

12.4 Motors of over 5.6 kilowatts in size shall be supplied at 3 phase an must be arranged for .reduced voltage starting. The Commission will be prepared to consider on written application, direct-on-line starting of motors of these sizes where the supply to the Consumer’s Installation is at high voltage.

12.5 Other apparatus not larger than 2.5 kilovolt-amperes in size can be supplied at either 115 or 230 volts, single phase.

12.6 Apparatus larger than 15 kilovolt-amperes in size and up to and including 15 kilovolt- amperes can only be supplied at 230 volts, single phase.

12.7 Apparatus larger than 15 kilovolt-amperes in size can only be supplied form a 3 phase supply.

12.8 In certain areas where only a single phase supply is available, an application to the Commission for the installation of apparatus mentioned in paragraphs (12.4 ) and (12.7) will be specially considered by the Commission.

12.9 Single phase appliances and motors supplied from 3 or 4 wire Installations shall be so connected that the operating current unbalanced will be a minimum.

12.10 Motors and appliances such as refrigerators, air conditioning units, video recorders, computers, microprocessor controlled equipment and television sets should be provided with devices for protection against voltage fluctuations, and other variations from normal supply conditions.

12.11 Three phase motors, apparatus and other equipment should be protected against single phasing conditions.

12.12 Consumers with voltage sensitive equipment must provide their own stabilizing equipment to meet the limits of the sensitivity of their equipment. In such cases the Consumers should consult the Commission before finalizing plans for installing such equipment.

12.13 Fluorescent and other lighting fittings of inherently poor power factor must be corrected to a value of at least 0.8 before being connected to any Installation supplied by the Commission.


13. General Information on the Commission’s Practices

13.1 Consumers are advised to provide adequate capacity in their Installation for reasonable use of appliances and equipment and in this respect proper planning of their installations is essential.

13.2 In view of the ever increasing use of electricity energy resulting in increasing load demands from Consumers it is recommended that spare capacity of at least 20 to 25% should be provided whenever Installations are being rewired and new switches, panels, feeders and circuits are being installed.

13.3 Electrical equipment must be used by Consumers bin such a manner as not to cause unusual voltage fluctuation or other disturbances to the Commission’s system. The Commission will require Consumers at their own expense to install suitable apparatus to limit such voltage fluctuations and disturbances. The Commission reserves the right to take whatever action it considers necessary to correct or prevent such disturbances from unduly affecting the quality of supply to other Consumers.

13.4 Consumers shall be responsible for the Commission’s equipment installed on their premises and in the event of any loss or damage to the property of the Commission caused by or arising out of carelessness, neglect or misuse by the Consumers or other unauthorized parties the cost of making good such loss or repair shall be paid by the Consumers.

13.5 The use of the Commission’s poles, towers, structures or other facilities for the purpose of fastening or supporting any radio equipment or any wire, ropes, signs, banners or anything of any nature or the locating of same in such proximity to the Commission’s Installations as to cause or be likely to cause interference with the supply of electricity is prohibited by the Commission and the Commission shall have the right to move such items without notice unless consent has been given by the Commission in writing.

13.6 The Commission shall use all diligence in supplying a regular and uninterrupted supply and will not be liable for damage occasioned by the interruptions which the Commission could not reasonably have foreseen and guarded against or where such interruptions are necessary for repairs or changes in the Commission’s generation, transmission or distribution equipment.

13.7 Consumers shall notify the Commission when their supply is interrupted or unsatisfactory.

13.8 Consumers and the general public are requested to notify the Commission of any defects, trouble or accidents affecting the Commission’s system or the supply of electricity.

13.9 Consumers shall permit identified and authorized employees of the Commission to enter their premises for purposes related to the supply of electricity.

13.10 Employees of the Commission are forbidden to demand or accept from the public or any Consumer reward for services rendered or to make, modify or alter any rates, terms, conditions or contracts or to waive negotiated contracts, rules and regulations under the Act by which the Commission operates.

13.11 Electrical energy purchased from the Commission shall be used by the Consumers only for the purpose specified in the applications and conditions for supply. Consumers shall not retail or otherwise dispose of electrical energy except with the written consent of the Commission and/or through the obtaining of he necessary licences as required by the Trinidad and Tobago Electricity Commission Act Chapter 54.70

13.12 The Consumer shall be charged for the use of electrical energy under the tariff which is most appropriate in relation to the use for which the Consumer requires the supply and/or the characteristics of the supply.

13.13 All previous notices, instructions, regulations or advice issued by the Commission which in any way conflict with the information contained in this booklet are now considered null and void.

13.14 The Commission reserves the right to impose upon the Consumer any further requirements not inconsistent with these regulations or to amend these regulations as may be deemed necessary in the interest of the Consumer and the Commission.

13.15 Rules and regulations in this booklet are not intended to conflict with existing rules and regulations of the Electricity (Inspection) Act Chapter 54.72 or any other authorities having jurisdiction.