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This Book was ranked at 10 by Google Books for keyword cat 5 wiring diagram. For simple installations the foregoing information may be given in a schedule, with a durable copy provided within or adjacent to each distribution board or consumer unit. This installation, or part of it, is protected by a device which automatically switches off the power supply if an earth fault develops.
Test quarterly by pressing the button marked ' V or 'Test' The device should switch off the supply and should be then switched on to restore the supply.
If the device does not switch off the supply when the button is pressed seek expert advice. Great care should be taken before undertaking extension, alteration or repair that all conductors are correctly identified,. The warning notice must have the wording in Figure 6.
This information must be positioned so as to be visible to a person who is modifying or extending the circuit Figure 6. Figure 6. Final circuits 7. For other voltages, the maximum circuit length given in the table must be corrected by the application of the formula. U 0 is the supply voltage. The conditions assumed are that: i the installation is supplied by a b c ii iii iv v vi a TN-C-S system with a maximum external earth fault loop impedance, Ze, of 0.
Method for cable type covered by Table 4D5 with a current rating factor of 0. Notes: 1 Wherever practicable, a cable should be fixed in a position such that it will not be covered with thermal insulation. The tables assume heating including water heating cables are not grouped. For cables of household or similar installations heating and water heating excepted , if the following rules are followed derating for grouping is not necessary: i Cables are not grouped, that is, they are separated by at least two cable diameters when installed under insulation, namely installation methods , , and For other groupings, ambient temperatures higher than 30 C or enclosure in thermal insulation, cable csa will need to be increased as per Appendix 6 of this Guide.
The length represents the total ring cable loop length and does not include any spurs. The total number of fused spurs is unlimited but the number of non-fused spurs is not to exceed the total number of socket-outlets and items of stationary equipment connected directly in the circuit. A non-fused spur feeds only one twin or multiple socket-outlet or one permanently connected item of electrical equipment.
Such a spur is connected to a circuit at the terminals of socket-outlets or at junction boxes or at the origin of the circuit in the distribution board. A fused spur is connected to the circuit through a fused connection unit, the rating of the fuse in the unit not exceeding that of the cable forming the spur and, in any event, not exceeding 13 A.
The number of socket-outlets which may be supplied by a fused spur is unlimited. The circuit is assumed to have a load of 20 A at the furthest point and the balance to the rating of the protective device evenly distributed. For a 32 A device this equates to a load of 26 A at the furthest point. The circuit is assumed to have a load equal to the rated current l n of the circuit protective device, evenly distributed along the circuit Where this is not the case, circuit lengths will need to be reduced where voltage drop is the limiting factor, or halved where load is all at the extremity.
The most onerous installation condition acceptable for the load and device rating is presumed when calculating the limiting voltage drop.
If the installation conditions are not the most onerous allowed see column 4 of Table 7. See note 1 to Table 7. However, the circuit cables must not require RCDs as per v and vi above, that is, circuit cables must be enclosed in earthed steel conduit or have an earthed metal sheath or be at a depth of 50 mm in a wall or partition without metal parts socket-outlet circuits in industrial and commercial premises where the use of equipment and work on the building fabric and electrical installation is under the supervision of skilled or instructed persons.
While these factors have generally been allowed for in the standard final circuits in Table 7. See Table 7. The distributor needs to be consulted as to the prospective fault current at the origin of the installation. Except for London and some other major city centres, the maximum fault current for V single-phase supplies up to A will not exceed 16 kA. In general, the fault current is unlikely to exceed Consumer units incorporating protective devices complying as a whole assembly with BS or BS EN are suitable for locations with fault currents up to 16 kA when supplied through a type II fuse to BS or BS 88 fuse rated at no more than A.
The difference between the two is the condition of the circuit-breaker after manufacturer's testing. Icn is the maximum fault current the breaker can interrupt safely, although the breaker may no longer be usable. Ics is the maximum fault current the breaker can interrupt safely without loss of performance. The lcn value in amperes is normally marked on the device in a rectangle, e. For domestic installations the prospective fault current is unlikely to exceed 6 kA, up to which value the I will equal Ics.
The short-circuit capacity of devices to BS EN is as specified by the manufacturer. Cartridge fuses to BS These are for use in domestic and similar premises, Cartridge fuses to BS Three types are specified: fuse links with a full-range breaking capacity for general application fuse links with a full-range breaking capacity for the protection of motor circuits fuse links for the protection of motor circuits.
Guidance on selection is given in Table 7. Type C or 3 may be necessary in highly inductive circuits such as banks of fluorescent lighting Wot suitable for general use Suitable for transformers, X-ray machines, industrial welding equipment, etc.
Note: ln is the nominal rating of the circuit-breaker. Disconnection times The protective device must operate within 0. Appendix 2 provides maximum permissible measured earth fault loop impedances for fuses, circuit-breakers and RCBOs.
A cable passing through a joist or ceiling support shall: i be at least 50 mm from the top or bottom, as appropriate, or ii have earthed armouring or an earthed metal sheath, or III be enclosed in earthed steel conduit ortrunking, or iv be provided with mechanical protection sufficient to prevent penetration of the cable by nails, screws and the like Note: the requirement to prevent penetration is difficult to meet.
Cables through joists Maximum depth of notch should be 0. M a x i m u m depth of notch should be 0. Holes in the same joist should be at least 3 diameters apart. In domestic and similar installations, cables not installed as per i, ii, iii or iv but complying with v shall be protected by a 30 mA RCD. In domestic and similar installations, cables installed in walls or partitions with a metal or part metal construction shall be either: a b installed as ii, iii or iv above, or protected by a 30 mA RCD.
For installations under the supervision of a skilled or instructed person, such as commercial or industrial where only authorized equipment is used and only skilled persons will work on the building, RCD protection as described above is not required.
Note: Domestic or similar are not considered to be under the supervision of skilled or instructed persons. For example, cables should not be in contact with or run alongside hot pipes.
D e f i n i t i o n s of v o l t a g e b a n d s Band I circuit: Circuit that is nominally extra-low voltage, i. Band II circuit: Circuit that is nominally low voltage, i. Note: Fire alarm and emergency lighting circuits must be separated from other cables and from each other, in compliance with BS and BS This is to prevent mains voltage appearing in telecommunication circuits with consequent danger to personnel. BS recommends that the minimum separation distances given in Tables 7.
Minimum separation distances between internal low voltage electricity supply cables operating in excess of 50 V a. Notes: 1 2 Where t h e LV cables share the same tray then the normal separation should be met.
Where LV and telecommunications cables are obliged to cross, additional insulation should be provided at t h e crossing point; this is not necessary if either cable is armoured. Under these circumstances, if line and neutral conductors or switch feeds and switch wires are not run close together, there may be interference with the induction loop. This can occur when a conventional two-way lighting circuit is installed. This effect can be reduced by connecting as shown in Figure 7.
T Figure 7. Further guidance is given in the IEE. A way of satisfying this requirement is to install socket-outlets and controls throughout the dwelling at a height of between 4 5 0 m m and m m from finished floor level. See Figure 8A in Appendix 8. Because of the sensitivity of circuit-breakers and RCDs fitted to consumer units, consumer units should be readily accessible. The guidance given in Approved Document M applies to all new dwellings. Note that if a dwelling is rewired there is no requirement to provide the measures described above providing that upon completion the building is no worse in terms of the level of compliance with the other Parts of Schedule 1 to the Building Regulations.
In a standard house single storey or multi-storey with no storey exceeding 2 0 0 m 2 floor area , the basic requirement can be met by installing interlinked smoke alarms as follows: 1 2 3 4 in circulation areas between sleeping places and places where fires are most likely to start, e.
See Figure 7. Positioning of equipment Equipment should be positioned as follows: i ii iii iv ceiling m o u n t e d alarms and detectors must be fixed at least 3 0 0 m m f r o m the walls and luminaires. They should not be fixed in bathrooms, showers, cooking areas or garages, or any other place w h e r e steam, condensation or f u m e s could give false alarms.
They should not be fixed over stairs or openings b e t w e e n floors. Wiring of smoke and heat alarms The detectors and alarms are required to: a b be linked so that the operation of o n e will initiate all units mains p o w e r e d smoke detectors may be interlinked by radio be permanently wired with an i n d e p e n d e n t circuit from the distribution board c o n s u m e r unit , or supplied f r o m a local, regularly used lighting circuit there should be a means of isolating t h e supply to the alarms w i t h o u t affecting the lighting.
N o t e : Where all circuits are protected by RCDs there is advantage in supplying fire detectors and alarms from regularly used lighting circuits. Other than for large houses the cables for the power supply to each self-contained unit and for the interconnections between self-contained units need have no fire survival properties and needs no special segregation. Equipment having a protective conductor current exceeding 10 mA should be connected by one of the following methods: i permanently connected to the wiring of the installation, with the protective conductor selected in accordance with Regulation The permanent connection to the wiring may be by means of a flexible cable ii a flexible cable with an industrial plug and socket to BS EN , provided that either: a the protective conductor of the associated flexible cable is of crosssectional area not less than 2.
Spurs, if provided, require high integrity protective conductor connections Figure 7. Ring final circuit supplying socket-outlets. Socket-outlets must have two terminals for protective conductors. One terminal to be used for each protective conductor, of a minimum size of 1.
Keep close to circuit conductors to reduce emc effects. Because of the presence of water, these locations are onerous for equipment and there is an increased danger of electric shock because of immersion of the body in water. The additional requirements can be summarised as follows: all the circuits of the location must be protected by 3 0 mA RCDs socket-outlets are not allowed within 3 metres of zone 1 the edge of the bath or shower basin ill protection against ingress of water is specified for equipment within the zones, see Table 8.
Supplementary bonding of locations containing a bath or shower is required unless all the following requirements are met: all circuits of the location meet the required disconnection times, all circuits of the location are additionally protected by 3 0 mA RCDs, and all extraneous-conductive parts within the location are effectively connected via the main protective equipotential bonding to the main earthing terminal.
SELV, the safety source installed outside the zones. The following mains voltage fixed, permanently connected equipment allowed: whirlpool units, electric showers, shower pumps, ventilation equipment, towel rails, water heaters, luminaires. Fixed permanently connected equipment allowed. General rules apply. Switchgear m A accessories None allowed. Only 12 V a. SELV switches, the safety source installed outside the zones. Only switches and sockets of SELV circuits allowed, the source being outside the zones, and shaver supply units complying with BS EN if fixed where direct spray is unlikely.
Socket-outlets allowed 3 m horizontally from the boundary of zone 1. The space under the bath is: Zone 1 if accessible without the use of a tool Outside the zones if accessible only with the use of a tool. Note: BS has further requirements for underfloor heating in Regulation Every installation must be inspected and tested during erection and on completion before being put into service to verify, so far as is reasonably practicable, that the requirements of the Regulations have been met.
Precautions must be taken to avoid danger to persons and to avoid damage to property and installed equipment during inspection and testing. If the inspection and tests are satisfactory, a signed Electrical Installation Certificate together with a Schedule of Inspections and a Schedule of Test Results as in Appendix 7 are to be given to the person ordering the work.
Inspection must precede testing and must normally be done with that part of the installation under inspection disconnected from the supply.
The purpose of the inspection is to verify that equipment is: i ii correctly selected and erected in accordance with BS and if appropriate its own standard not visibly damaged or defective so as to impair safety. When a test shows a failure to comply, the installation must be corrected. Where appropriate during this measurement, line and neutral conductors may be connected together polarity: this includes checks that single-pole control and protective devices e.
Electrical testing involves danger. It is t h e test operative's duty to ensure his or her o w n safety, and t h e safety of others, in the performance of t h e test procedures. W h e n using test instruments, this is best achieved by precautions such as: i an understanding of t h e correct application and use of t h e test instrumentation, leads, probes and accessories to be e m p l o y e d it checking that the test instrumentation is m a d e in accordance w i t h t h e appropriate safety standards such as BS EN for t w o - p o l e voltage detectors and BS EN or BS EN 6 1 5 5 7 for instruments Hi checking before each use that all leads, probes, accessories including all devices such as crocodile clips used to attach to conductors and instruments including t h e proving unit are clean, u n d a m a g e d and functioning; also, checking that isolation can be safely effected and that any locks or other means necessary for securing t h e isolation are available and functional iv observing the safety measures and procedures set out in HSE Guidance Note GS 3 8 for all instruments, leads, probes and accessories.
S o m e test instrument manufacturers advise that their instruments be used in conjunction w i t h fused test leads and probes. Others advise the use of non-fused leads and probes w h e n t h e instrument has in-built electrical protection, but it should be noted that such electrical protection does not extend to the probes and leads.
Note: The advice given does not preclude other test methods. Tests should be carried out in t h e following sequence. Results obtained during the various tests should be recorded on the Schedule of Test Results Appendix 7 for future reference and checked for acceptability against prescribed criteria.
Test p r o c e d u r e s Continuity of circuit proteetiwe conductors and protective bonding conductors for ring final circuits see Test methods 1 and 2 are alternative ways of testing the continuity of protective conductors. Every protective conductor, including circuit protective conductors, the earthing conductor, main and supplementary bonding conductors, should be tested to verify that the conductors are electrically sound and correctly connected.
Use an ohmmeter capable of measuring a low resistance for these tests. Such installations should be inspected for soundness of construction and test method 1 or 2 used to prove continuity. Bridge the line conductor to the protective conductor at the distribution board so as to include all the circuit.
Then test between line and earth terminals at each point in the circuit. If the instrument does not include an 'auto-null' facility, or this is not used, the resistance of the test leads should be measured and deducted from the resistance readings obtained. Figure Connections for testing continuity of circuit protective conductors using test method 1. Connect one terminal of the test instrument to a long test lead and connect this to the installation main earthing terminal.
Connect the other terminal of the instrument to another test lead and use this to make contact with the protective conductor at various points on the circuit, such as luminaires, switches, spur outlets, etc. Continuity test method 2 For main bonding, connect one terminal of the test instrument to a long test lead and connect this to the installation main earthing terminal.
Connect the other terminal of the instrument to another test lead and use this to make contact with the protective bonding conductor at its further end, such as at its connection to the incoming metal water, gas or oil service. The connection verified boxes on the Electrical Installation Certificate should be ticked if the continuity of the earthing conductor and of each main bonding conductor is satisfactory, and the details of the material and the cross-sectional areas of the conductors recorded.
A three-step test is required to verify the continuity of the line, neutral and protective conductors and the correct wiring of a ring final circuit. The test results show if the ring has been interconnected to create an apparently continuous ring circuit which is in fact broken, or wrongly wired. Use a low-resistance ohmmeter for this test. These resistances are n, r n and r 2 respectively.
A finite reading confirms that there is no open circuit on the ring conductors under test. The resistance values obtained should be the same within 0. If the protective conductor has a reduced csa the resistance r 2 of the protective conductor loop will be proportionally higher than that of the line and neutral loops e.
If these relationships are not achieved then either the conductors are incorrectly identified or there is something w r o n g at one or more of the accessories. Figure Step 2 The line and neutral conductors are then connected together at the distribution board so that the outgoing line conductor is connected to the returning neutral conductor and vice versa see Figure The resistance between line and neutral conductors is measured at each socket-outlet. The readings at each of the sockets wired into the ring will be substantially the same and the value will be approximately one-quarter of the resistance of the line plus the neutral loop resistances, i.
Any sockets wired as spurs will have a higher resistance value due to the resistance of the spur conductors. Note: Where single-core cables are used, care should be taken to verify that the line and neutral conductors of opposite ends of the ring circuit are connected together. An error in this respect will be apparent f r o m the readings taken at the socket-outlets, progressively increasing in value as readings are taken towards the midpoint of the ring, then decreasing again towards the other end of the ring.
Step 3 The above step is then repeated, this time with the line and cpc cross-connected see Figure The resistance between line and earth is measured at each socket. The readings obtained at each of the sockets wired into the ring will be substantially the same and the value will be approximately one-quarter of the resistance of the line plus cpc loop resistances, i.
As before, a higher resistance value will be recorded at any sockets wired as spurs. The value can be used to determine the earth fault loop impedance Zs of the circuit to verify compliance with the loop impedance requirements of BS see Step 3: The line and cpc conductors are cross-connected and the resistance measured at each socket-outlet.
Tests should be carried out using the appropriate d. The tests should be made at the distribution board with the main switch off, all fuses in place, switches and circuit-breakers closed, lamps removed and other current-using equipment disconnected. Where a circuit contains two-way switching, the two-way switches must be operated one at a time and further insulation resistance tests carried out to ensure that all the circuit wiring is tested. Table Insulation resistance measurements are usually much higher than those of Table More stringent requirements are applicable for the wiring of fire alarm systems in buildings, see BS In these circumstances, each circuit should then be tested separately.
Where surge protective devices SPDs or other equipment such as electronic devices or RCDs with amplifiers are likely to influence the results of the test or may suffer damage from the test voltage, such equipment must be disconnected before carrying out the insulation resistance test. Where it is not reasonably practicable to disconnect such equipment, the test voltage for the particular circuit may be reduced to V d.
Where the circuit includes electronic devices which are likely to influence the results or be damaged, only a measurement between the live conductors connected together and earth should be made and the value should be not less than the value stated in Table Resistance readings obtained should be not less than the minimum value referred to in Table For a circuit containing two-way switching or two-way and intermediate switching,.
Notes: 1 The test may initially be carried out on the complete installation. Three-phase Test to earth from all live conductors including the neutral connected together. Where disconnecting all equipment. The method of test prior to connecting the supply is the same as test method 1 for checking the continuity of protective conductors which should have already been carried out see For ring final circuits a visual check may be required see It is important to confirm that: 1 2 3 overcurrent devices and single-pole controls are in the line conductor, except for El4 and E27 lampholders to BS EN , centre contact screw lampholders have the outer threaded contact connected to the neutral, and socket-outlet polarities are correct.
After connection of the supply, polarity must be checked using a voltage indicator or a test lamp in either case with leads complying with the recommendations of HSE Guidance Note GS This impedance reading is treated as the electrode resistance and is then added to the resistance of the protective conductor for the protected circuits.
The test should be carried out before energising the remainder of the installation. The measured resistance should meet the following criteria and those of For TT systems, the value of the earth electrode resistance RA in ohms multiplied by the operating current in amperes of the protective device lAn should not exceed 50 V.
The effectiveness of the distributor's earth must be confirmed by a test. The external impedance Z e may be measured using a line-earth loop impedance tester. The main switch is opened and made secure to isolate the installation from the source of supply. The earthing conductor is disconnected from the main earthing terminal and the measurement made between line and earth of the supply.
Direct measurement of Z s can only be made on a live installation. Neither the connection with earth nor bonding conductors are disconnected.
This must be taken into account when comparing the results with design data. Care should be taken to avoid any shock hazard to the testing personnel and to other persons on site during the tests. The value of Z s determined for each circuit should not exceed the value given in Appendix 2 for the particular overcurrent device and cable.
This test should be carried out before energising other parts of the system. Mote: For further information on the measurement of earth fault loop impedance, refer to Guidance Note 3 Inspection and Testing. Designs should be based on the maximum fault current provided by the distributor see 7. If it is desired to measure prospective fault levels this should be done with all main bonding in place. Measurements are made at the distribution board between live conductors and between line conductors and earth.
For three-phase supplies, the maximum possible fault level will be approximately twice the single-phase to neutral value. For three-phase to earth faults, neutral and earth path impedances have no influence. Switchgear, controls, etc. A new requirement has been introduced into BS that, where required, it should be verified that voltage drop does not exceed the limits stated in relevant product standards of installed equipment.
Where no such limits are stated, voltage drop should be such that it does not impair the proper and safe functioning of installed equipment. Typically, voltage drop will be evaluated using the measured circuit impedance. The requirements for voltage drop are deemed to be met where the voltage drop between the origin and the relevant piece of equipment does not exceed the values stated in Appendix 12 of BS It should be remembered that voltage drop may exceed the values stated in Appendix 12 in situations such as motor starting periods and where equipment has a high inrush current where such events remain within the limits specified in the relevant product standard or reasonable recommendation by a manufacturer.
Residual current device RCD is the generic term for a device that operates when the residual current in the circuit reaches a predetermined value.
An RCD is a protective device used to automatically disconnect the electrical supply when an imbalance is detected between the line and neutral conductors. In the case of a single-phase circuit, the device monitors the difference in currents between the line and neutral conductors.
In a healthy circuit, where there is no earth fault current or protective conductor current, the sum of the currents in the line and neutral conductors is zero. If a line to earth fault develops, a portion of the line conductor current will not return through the neutral conductor.
The device monitors this difference, operates and disconnects the circuit when the residual current reaches a preset limit, the residual operating current l An.
The tests are made on the load side of the RCD, as near as practicable to its point of installation and between the line conductor of the protected circuit and the associated circuit protective conductor.
The load supplied should be disconnected during the test. With a leakage current flowing equivalent to 50 per cent of the rated tripping current, the device should not open. With a leakage current flowing equivalent to per cent of the rated tripping current of the RCD, the device should open in less than ms.
With a leakage current flowing equivalent to per cent of the rated tripping current of the RCD, the device should open in less than ms unless it is of Type S' or selective which incorporates an intentional time delay. In this case, it should trip within a time range from ms to ms. The maximum test time must not be longer than 40 ms, unless the protective conductor potential rises by less than 50 V.
The instrument supplier will advise on compliance. An integral test device is incorporated in each RCD. This device enables the electrical and mechanical parts of the RCD to be verified, by pressing the button marked T or 'Test' Figure Operation of the integral test device does not provide a means of checking: a b c the continuity of the earthing conductor or the associated circuit protective conductors any earth electrode or other means of earthing any other part of the associated installation earthing.
The test button will only operate the RCD if the device is energised. Confirm that the notice to test RCDs quarterly by pressing the test button is fixed in a prominent position see 6. In Figure In a healthy circuit, w h e r e there is no earth fault current or protective conductor current, t h e s u m of t h e currents in t h e line and neutral conductors is zero.
If a line to earth fault develops, a portion of t h e line conductor current will not return through t h e neutral conductor.
The device monitors this difference, operates and disconnects t h e circuit w h e n the residual current reaches a preset limit, t h e residual operating current l A n. This appendix provides information on the determination of the maximum demand for an installation and includes the current demand to be assumed for commonly used equipment.
It also includes some notes on the application of allowances for diversity. The information and values given in this appendix are intended only for guidance because it is impossible to specify the appropriate allowances for diversity for every type of installation and such allowances call for special knowledge and experience.
The values given in Table 1B, therefore, may be increased or decreased as decided by the installation designer concerned. No guidance is given for blocks of residential dwellings, large hotels, industrial and large commercial premises; such installations should be assessed on a case-by-case basis. The current demand of a final circuit is determined by adding the current demands of all points of utilisation and equipment in the circuit and, where appropriate, making an allowance for diversity.
Typical current demands to be used for this addition are given in Table 1A. The current demand of an installation consisting of a number of final circuits may be assessed by using the allowances for diversity given in Table 1B which are applied to the total current demand of all the equipment supplied by the installation. The current demand of the installation should not be assessed by adding the current demands of the individual final circuits obtained as outlined above. In Table 1B the allowances are expressed either as percentages of the current demand or, where followed by the letters f.
The current demand for any final circuit which is a standard circuit arrangement complying with Appendix 8 is the rated current of the overcurrent protective device of that circuit. An alternative method of assessing the current demand of an installation supplying a number of final circuits is to add the diversified current demands of the individual circuits and then apply a further allowance for diversity.
In this method the allowances given in Table 1B should not be used, the values to be chosen being the responsibility of the installation designer. Appendix The use of other methods of determining maximum demand is not precluded where specified by the installation designer. After the design currents for all the circuits have been determined, enabling the conductor sizes to be chosen, it is necessary to check that the limitation on voltage drop is met.
At least 0. Final circuits for discharge lighting must be arranged so as to be capable of carrying the total steady current, viz. Where m o r e exact information is not available, t h e d e m a n d in volt-amperes is taken as the rated lamp watts multiplied by not less than 1.
This multiplier is based upon the assumption that the circuit is corrected to a power factor of not less than 0. L of remaining appliances O. L of remaining appliances No diversity allowablet No diversity allowablet No diversity allowablet o X c rt X. L of remaining appliances o. L of remaining appliances. The tables in this appendix provide m a x i m u m permissible measured earth fault loop impedances Z s for compliance with BS where the standard final circuits of Table 7.
The values are those that must not be exceeded in the tests carried out under Table 2E provides correction factors for other ambient temperatures. For each type of fuse, t w o tables are given: where the circuit concerned is a final circuit not exceeding 32 A or a distribution circuit and the m a x i m u m disconnection t i m e for compliance with Regulation The tabulated values apply only w h e n the nominal voltage to Earth U 0 is 2 3 0 V.
Appendix Note: The impedances tabulated in this appendix are lower than those in Tables The correction factor divisor used is 1. The Guide includes material not included in BS , it provides background to the intentions of BS and gives other sources of information. However, it does not ensure compliance with BS It is a simple guide to the requirements of BS ; electrical installers should always consult BS to satisfy themselves of compliance.
It is expected that persons carrying out work in accordance with this guide will be competent to do so. For example, an installation in licensed premises may have requirements which differ from or are additional to those of BS , and these will take precedence. Part 1 This Guide is concerned with limited application of BS in accordance with paragraph 1.
BS and the On Site Guide are not design guides.
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