***Useful Information For The Working Sparky***

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17TH Edition , Questions & Answers for Examination 2382-10 Requirements for
1. The external influence code ACM requires IP rated equipment to
a. IPX4
b. IPX1
c. IPO
d. IPX2

Electrical Installations



2. AS 7671 is a
a. document designed solely for the use of electricians
I. legal document used in a court of law
c. Bon statutory document
d. statutory document

3. The fundamental principles of BS7671 state that persons and livestock shall be protected against injury as a
consequence of over voltages originating from
a. motors running
I. the operation of circuit breakers
c. atmospheric events
d. voltage recovery

4. The fundamental principles of BS 7671 covering the protection against voltage disturbances etc., states that the
installation shall have an adequate level of immunity against
a. the weather
b. electromagnetic disturbances
c. voltage loss
d. vibration

5. What is the maximum As for a 10A type C circuit breaker protecting a standard discharge type lighting circuit?
a. 1.15 Ohms
I. 2.30Ohms
c. 1.44Ohms
d. 1.92Ohms

6. A double insulated hand held electric drilling machine is known as
a. class II equipment
b. a DeWalt
c. class HI equipment
d. class I equipment

7. An electrical installation certificate should be signed by
a. the local authority
b. a competent person
c. the customer
d. the REC

8. When considering external influences, the code AD4 requires IP rated equipment to
a. IPXO
b. IPX1
c. IPX4
d. IPX5

9. The external influence code AD1 requires IP rated equipment to
a. IPX4
b. IPX1
c. IPXO
d. IPX2

10. When considering external influences, the code AA5 relates to the ambient temperature range
a. -5°C to +45°C
b. -65°C to +5°C
c. +5°C to +40°C
d. -25°C to 0°C


11. When considering external influences, the code AA1 relates to the ambient temperature range
a. -5°C to +45°C
b. -60°C to +5°C
c. +5°C to +40°C
d. -25°C to 0°C

12. Electrical installations shall be divided into circuits to
a. allow easier access to the installation
b. allow more even distribution of power
c. allow for expansion without changing the maximum demand
d. reduce electromagnetic interference

13. One method of determining the external loop impedance is by taking a reading at
a. the origin of supply
b. the supply and furthest outlet
c. the supply and subtracting the values of R1 + R2
d. the furthest outlet from the supply origin

14. The maximum disconnection time for a 230V a.c. final circuit not exceeding 32 amps, with a TT supply is
a. 3s
b. 0.2s
c. 0.5s
d. 5ms

15. The maximum Zs for a 16A Type B circuit breaker protecting a fixed appliance is
a. 1.87 Ohm
b. 0.87Ohm
c. 2.40Ohm
d. 2.87Ohm

16. Undervottage protection is required when the restoration of power may cause
a. accidental RCD tripping
b. unexpected stalling of the motor
c. overload activation
d. unexpected start-up of the machinery

17, A device which cuts off all or part of an installation from every source of electrical energy provides
a. emergency switching
b. isolatior
c. a fireman's switch
d. partial disconnection

18. For a 32A Type B circuit breaker protecting a standard final ring circuit, the maximum Zs would be
a. 0.70 Ohm
b. 0.30 Ohm
c. 1.44 Ohm
d. 0.20 Ohm

19. In a TT installation, distribution circuits must satisfy a disconnection time of
a. 5s

b. 1s
c. 0.6s
d. 0.2s

20. A residual current device (RCD) works by
a. a magnetic device operating in the event of a fault between Live and earth «-> CORRECT ANSWER
b. a magnetic device operating in the event of a fault between neutral and earth
c. a thin element operating in the event of a fault between neutral and earth
d. a thin element operating in the event of a fault between live and earth

21. A RCBO offers protection against
a. short circuit current
b. short circuit and earth fault current
c. short circuit and overload current
d. basic contact

22. Protective measures against electric shock can be achieved by automatic disconnection of the supply and in systems additional protection by means of an red shall be provided for
a. mobile equipment with a current rating exceeding 32 A
b. mobile equipment with a current not exceeding 22 A
c. socket outlets with a rated current exceeding 20 A
d. socket outlets with a rated current not exceeding 20 A
systems additional protection by means of an rcd shall be provided for

23. Protective measures against electric shock can be achieved by automatic disconnection of the supply and in systems additional protection by means of an red shall be provided for
a. socket outlets with a rated current exceeding 20 A
b. socket outlets with a rated current not exceeding 13 A
c. mobile equipment with a current rating not exceeding 32 A
d. mobile equipment with a current rating exceeding 32 A

24. In a.c. systems in the event of the failure of basic protection, additional protection may be provided by
a. supplementary bonding
b. a time delay 100mA RCD
c. an RCD with an operating current not exceeding 30mA
d. electrical separation

25. If a fault occurs in the HV system, and a magnitude of fault voltage of 430 volts occurs between exposed conductive
parts and earth on the LV installation. What is the maximum tolerable duration of the fault?
a. 10 ms
b. 100 ms
c. 200 ms
d. 300 ms

26. If a Line conductor of an IT system is earthed accidentally, the insulation and components rated for the Line to
Neutral voltage can be temporarily stressed with a higher voltage. What value can this stress voltage reach up to?
a. U=V3 U0
b. U=3U0
c. U=V U0
d. U=U0

27. Nuisance tripping from a large transformer installation can be prevented by
a. the use of an RCD
b. the use of a C type MCB
c. the use of a B type MCB
d. the use of a D type MCB

28. In order to reduce the effects of eddy currents when conductors are drawn through a steel conduit system, they
should be arranged so that
a. they are terminated in the correct phase sequence
b. each conductor of an individual circuit takes approximately the same current
c. they are physically separated from the conductors of other circuits within the conduit
d. they are not individually surrounded by the ferrous material -> CORRECT ANSWER

29. If a cable is buried in a wall less than 50mm depth and is not protected by metallic enclosures, the additional
protection required is
a. RCD protection -
b. MCB protection
c. supplementary bonding
d. external notification of cable routes

30. At which one of the following terminations would a warning notice NOT need to be attached
a. a copper water pipe
b. a bonded gas pipe
c. an earthing terminal within a consumer unit
d. an earth electrode

31. When determining design current, the correction factor that is applied to a BS3036 rewirable fuse is
a. 0.752
b. 0.527
c. 0.725
d. 1.725

32. A BS1361 protective device is also known as a
a. circuit breaker
b. cartridge fuse
c. RCD
d. semi enclosed rewirable fuse

33. An installation protected by an RCD shall have a fixed notice stating
a. the test button should be pressed occasionally
b. the test button should be pressed monthly
c. the test button should be pressed quarterly
d. the test button should be pressed at 6 monthly intervals

34. When insulated a PEN conductor shall be identified with
a. blue insulation along its length
b. green insulation and blue markings at the termination
c. green and yellow insulation and blue markings at the termination
d. green and yellow insulation along its length

35. Outdoor lighting does NOT involve
a. shelters
b. festoon lighting
c. road trafic signals
d. floodlighting

36. Where it is necessary to install cables within a wall consisting of a metal construction, the circuit should
a. adequately bond the studwork
b. be RCD protected
c. be MCB protected
d. be sheathed in metallic conduit

37. Where it is necessary to limit the consequences of the risk of fire due to fault currents, an RCD
a. shall be installed at the end of the circuit to be protected

 

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b. shall be installed at the origin of the circuit to be protected
c. is used to switch off the line conductor in the event of a faun
d. is used to switch off the neutral conductor in the event of a fault

38. In Great Britain the use of Combined protective and neutral (PEN) conductors is prohibited in consumers installations by which regulations?
a. The Electricity at Work Regulations 1989
b. The Supply of Machinery (Safety) Regulations 1992
c. The IEE Wiring Regulations
d. The Electricity Safety, Quality and Continuity Regulations 2002

39. In Great Britain the use of Combined protective and neutral (PEN) conductors is prohibited in consumers installations. One of the exceptions from this is
a. where the supply is feeding an agricultural installation
b. where the installation is supplied by a privately owned transformer which has a metallic connection with the distributors
network
c. where the supply is obtained from a private generating plant
d. where the supply is feeding a swimming pool

40. Where a generating set is used as an additional source of supply in parallel with other sources, it shall be instated
a. on the supply side of all the protective devices for the final circuits of the installation with a number of additional
requirements
b. on the supply side of all the protective devices for the final circuits of the installation with no additional requirements ~>
c. on the load side of all the protective devices for the final circuits of the installation with no additional requirements
d. on the load side of all the protective devices to the final circuit which must be connected by plug and socket

41. Regarding auxiliary supplies to safety services, the maximum changeover time refers to
a. how long the safety source can supply the rated power output to the safety service
b. the frequency (in cycles per second) of the auxiliary supply feeding the safety service
c. how often maintenance has to be carried out on the auxiliary supply
d. the time It takes for the safety source to supply the power to the safety service, after the loss of the main power supply

42. The minimum value of insulation resistance test performed on a PELV installation is
a. 10.0 MOhm
b. 2.0 MOhm
c. 0.3 MOhm
d. 0.5 MOhm

43. The minumum value of insulation resistance test performed on a SELV installation is
a. 99.0 MOhm
b. 2.0 MOhm
c. 0.3 MOhm
d. 0.5 MOhm

44. During the initial verification of an installation, which of the following forms part of the checklist?
a. maximum demand and diversity
b. Design briefs
c. contractors notes
d. presence of diagrams and instructions

45. An earth fault loop impedance test performed on a final ring circuit will record
a. the external loop impedance
b. the resistance of the line and protective conductors and external loop impedance
c. the resistance of the line and protective conductors
d. the protective conductor resistance

46. A polarity test would be conducted to verify
a. every fuse and single pole device is connected in the line conductor only -
b. there is sufficiently low resistance to operate the protective device within its limits
c. there is sufficient circuit protection
d. there is no breakdown of the conductor insulation

47. The minimum value of insulation resistance of a PELV circuit is
a. 0.5 MOhm
b. 1MOhm
c. 1.5 MOhm
d. 5MOhm

48. Within an agricultural installation, bonding conductors can be
a. 6.0mm2 aluminium conductors
b. 4.0mm2 aluminium conductors
c. 4.0mm2 copper conductors
d. 5.0mm2 copper conductors

49. Self supported suspension cables within agricultural situations should be
a. at a height of a least 2m
b. at a height of a least 4m
c. at a height of a least 6m
d. at a height of a least 10m

50. If SELV or PELV is used within agricultural premises, barriers or enclosures must conform to at least
a. IP4X
b. IPXXB
c. IPX4
d. IP67

51. Within zone 2 of an outdoor swimming baths where no water jets are used, installed electrical equipment should be rated
a. IPX4
b. IP2X
c. IPXXB
d. 1PX8

52. In an area containing a bath or a shower, socket outlets must be installed
a. 3m horizontally from zone 1
b. 3m horizontally from zone 0
c. 3m horizontally from zone 2
d. within zone 2 but outside zone 1

53. Where contact with skin or footwear is likely, the floor temperature of an underfloor heating installation should be limited to
a. 20°C
b. 35°C •
c. 40°C
d. 70°C


54. A mobile unit should have a connection between the
a. live and neutral
b. neutral and earth
c. vehicle chassis and main bonding terminal
d. battery terminals and supply

55. On the d.c. side of a PV power supply system, the type of insulation that is preferable is
a. Class II-
b. Class I
C XLPE

d. 1000v VDS

56. In marina installations that are NOT in an area subject to vehicle movement, overhead distribution cables shaft be installed at a height of
a. 5.5m
b. 4.5m
c. 6.5m
d. 3.5m

57. In areas that are not subject to vehicle movement on a caravan site, overhead distribution cables shall be installed at a heigth of
a. 6m
b. 3.5m
c. 5m
d. 10m



58. BS 6004 relates to
a. emergency lighting
b. electrical cables
c. 13A plug cartridge fuses
d. RCDs

59. BS 5266 relates to
a. emergency lighting -
b. electrical cables
c. 13A plug cartridge fuses
d. 13A plugs

60. The correction factor for three multicore cables installed in single layer fashion on a wail is
a. 0.75
b. 0.85
c. 0.79
d. 0.99


ANSWERS

1-a 2-c 3-c 4-b 5-b 6-a 7-b 8-c 9-c 10-c 11-b 12-d 13-a 14-b 15-d 16-d 17-b 18-c 19-b

20-a 21-b 22-d 23-c 24-c 25-d 26-a 27-d 28-d 29-a 30-c 31-c 32-b 33-c 34-c 35-b 36-b

37-b 38-d 39-c 40-b 41-d 42-d 43-d 44-d 45-b 46-a 47-a 48-c 49-c 50-b 51-a 52-a 53-b

54-c 55-a 56-d 57-b 58-b 59-a 60-c
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17th Edition stuff , Part 4 -
Protection for Safety :

Part 4 is reorganised with subject matter more closely grouped eg basic requirements and application requirements are now in the same chapter.
Part 4 has also a number of important changes.
Protection against direct contact has been replaced by “basic protection” which is defined as:- protection against electric shock under fault free conditions.
Protection against indirect contact has been replaced by “fault protection” which is defined as:- protection against electric shock under single fault conditions.
EEBADS is now an out of date term referring only to fault protection measures and this is now replaced by ADS:- Automatic Disconnection of Supply, which is a protective measure including both basic and fault protection.
Table 41A – Maximum disconnection times, has been extended and modified. Now replaced by table 41.1 this new table includes final TN and for the first time TT circuits. Disconnection times for circuits not exceeding 32A are tabulated for a range of ac and dc nominal line voltages
E.g.:
for a 230V I6A TN circuit t = 0.4s
for a 230V 16A TT circuit t = 0.2s
for final circuits exceeding 32A:- for a 230V TN circuit, t = 5s : max for a 230V TT circuit t = 1s max :

The terms fixed and non fixed equipment have been removed and no longer apply e.g. for previous fixed equipment in a TN circuit the value of 5s no longer applies and is now covered in table 41.1 as 0.4s or for circuits exceeding 32A, 5s.
As well as maximum disconnection times for TT systems being introduced into BS 7671 where an RCD is used for earth fault protection in a TT system an additional condition must be met. This is that RA x I∆n ≤ 50V (section 411.5.3).

 

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2392-10 : just off the press this is the New Sh—there hitting you with ,


(42) Prospective Short Circuit Current is Measured at the Supply with the Main Earthing Conductor :
(a) Connected to the Main Earth Terminal :
(b) Connected to the Neutral Supply :
(c) Disconnected from the Main Earth Terminal : *****
(d) Connected to the Line Supply :

Measurement of Prospective Short Circuit Current :
CCU :
Note : the Neutral & Earth Probes are Connected to the Natural Terminal ( Line by is self )
Note : Not on the ( MET ) Main Earthing Terminal ( Earth Connection Block :

(41) Prospective Earth Fault Current ( PEFC ) is Measured between :
(a) Line & Neutral :
(b) Line & Earth : *****
(c) Neutral & Earth :
(d) R1 & R2
Measurement of Prospective Earth Fault Current :
CCU :
Note : the Neutral Probe (N) Only : the Line Probe ( L ) Only :
Note : Earth Probe : on the ( Earth Connection Block : ( MET )

(40) Prospective Short Circuit Current ( PSCC ) is Measured between :
(a) Line & Neutral : *****
(b) Line & Earth :
(c) Neutral & Earth :
(d) R1 & R2

(0)Measurement of External Loop Impedance : ( Ze )
CCU :
Note : the main Earth is Disconnected from main bonding conductors and Circuit Protective conductors for this Test ,
Note : Main Switch in “ OFF “ Position :
Note : the Neutral Probe (N) Only : the Line Probe ( L ) Only :
Note : Earth Disconnected from the ( MET ) Main Earthing Terminal

(37) RCD tests should include :
(a) Half times /no trip , 1 times 40mS , 5 times / 0.45 ,
(b) Half times / 40mS , I times no trip , 5 times / 300ms ,
(c) Half times / no trip , I times 300mS , 5 times / 40mS **** ( am basing them on BS-EN - )
(d) Half times / 0.45 , I times 30mS , 5 times / 300mS ,

(31) When checking Polarity with test probes the voltage indication on a single phase socket outlet should be :
(a) L-N 230V , L-E 230V , N-E , 230V
(b) L-N 230V , L-E 0V , N-E , 230V
(c) L-N 0V , L-E 230V , N-E , 0V ,
(d) L-N 230V , L-E 230V , N-E , 0V , *****

( 47) An Electrical Installation Certificate consists of : ( Remember this One a Must ) ↔↔↔↔↔↔↔↔↔↔↔↔↔
(a) A two page Certificate :
(b) A two page Certificate and Schedule of Inspections :
(c) A two page Certificate and Schedule of Test Results :
(d) A two page Certificate, A Schedule of Inspections and a Schedule of Test Results :

(48) The Electrical Certificate required to be completed for a domestic shower circuit would be : ( Remember this One a Must ) ↔↔↔
(a) A Minor Works Electrical Installation Certificate :
(b) A Minor Works Electrical Installation Certificate and a Schedule of Test Results :
(c) A Minor Works Electrical Installation Certificate and a Schedule of Inspections and a Schedule of Test Results : *****
(d) No Certification Required :

( 47) ( D ) Ops

(49) Volt drop in a cable will :
(a) Increase with Increase in Length : *****
(b) Decrease with increase in Length :
(c) Not affected by increase in Length :
(d) Increase with a reduction in length :

(44) Voltage drop can be evaluated by using which one of the following test values :
(a) External Loop Impedance (Ze ) :
(b) Final Circuit earth Fault loop Impedance (Zs ) : *****
(c) Insulation Résistance :
(d) RCD tripping times :

2392-10 : Certificate in Fundamental Inspection and Initial Verification of Electrical Installations

(1) An initial verification is carried out to ensure that :
(a) All fixed equipment , parts and material are erected correctly to British Standards : *****
(b) No claim can be made for poor workmanship :
(c) A certificate is issued to the tenant of the property :
(d) The building insurance policy cast is kept to a minimum :

(2) Three items of information required for the initial inspection are :
(a) Maximum demand , type of earthing and supply characteristics : *****
(b) Cost of work, time taken and number of electricians :
(c) Serial number of instrument , schedule of test results , order number :
(d) Estimated time , start time and total hours taken :

(3) Three statutory and non statutory most relevant guidance materials for initial verification :
(a) COSHH regs , CDM regs , and PUWER regs , :
(b) Working at Height regs , and Working in Confined Spaces Act :
(c) Health and Safety Policy , Liability insurance and building insurance :
(d) EAWR 1989 , BS-7671:2008 , and IEE guidance notes 3 : *****

(4) Three locations and associated equipment requiring specific guidance material would be :
(a) Bedroom ,Lounge and Garage :
(b) Roofs , Cellars and Lofts :
(c) Explosive atmospheres , combustible dust and open cast mines : ( Mac two Answers on sheet C / D ) ???????? Help
(d) Offices , workrooms and classrooms :

(5) Some of the essential and optional information required on the Electrical Installation Certificate and Minor Electrical Installation Work Certificate is :
(a) Number of rooms , type of lighting , outdoor supplies :
(b) Floor area , separate building , number of floors ,
(c) Means of earthing , main protective conductors and supply characteristics : *****
(d) Name of sub-contractor , invoice , contact number :

(6) Two human senses that may be employed during the initial verification are :
(a) Thought and speech :
(b) Movement and pain :
(c) Gut feeling and taste :
(d) Sight and touch : *****

(7) Two main items to be checked for given systems and locations are :
(a) Light levels and stroboscopic effect :
(b) Number of appliance and Pat test labelling :
(c) Connection of conductors and cable selection : *****
(d) Empty premises or tenanted :

(8) Two requirements of the EAWR 1989 for safe inspection and testing are :
(a) Excess current protection and means of isolation : *****
(b) Two inspectors are required and one person under supervision :
(c) Presence of tenant and building inspector during verification :
(d) Spare instrument batteries and spare test leads :

(9) Instruments should be in accordance with :
(a) HSG 141 ,
(b) GS-38 , *****
(c) BS-7671 ,
(d) IEE Guidance Note 3 ,

(10) The correct Instruments or settings required to carry out domestic installation testing are ,
(a) Multimeter , Ammeter , Voltmeter and Watt meter ,
(b) Low insulation tester , light meter , power meter ,
(c) Pipe locator , cable finder , fuse checker and buzzer ,
(d) Continuity , insulation , loop impedance and RCD , ***** GN-3

(11) The first three tests to carry out on an initial verification are :
(a) Verification of switch operation , fuse test and lamp test ,
(b) Continuity of protective conductors , continuity of ring and insulation résistance , ***** GN-3
(c) Verification of voltage drop , functional testing of polarity ,
(d) Electrical separation , earth electrode test and phase sequence ,

(12) The four earthing arrangements in a domestic installation are ,
(a) Cross bond , main earth , earth electrode and supply cable earth ,
(b) Protective conductors in lighting , socket outlets , cooker and shower ,
(c) Bonding conductors to Gas , Water , Central heating and kitchen sink ,
(d) Main earth , main bonding , circuit protective conductors and supplementary bonding , *****

(13) Continuity of protective conductors gives a reading of ,
(a) R1 + Rn ,
(b) Ze + Zs ,
(c) R1 + R2 , ***** ( remember they are not asking you about little r1 + r2 , End to End
(d) r1 + r2 ,

(14) Increasing conductor length and decreasing conductor cross sectional area , ( CSA )
(a) Increases résistance , ***** Remember this one ,
(b) Decreases résistance ,
(c) Has no effect on résistance ,
(d) Causes the résistance value to remain the same due to both changes ,

(15) An increase in ambient temperature would cause the résistance of a conductor to ,
(a) Increase ,
(b) Decrease ,
(c) Vary ,
(d) Remain the same ,

(16) Connecting conductors’ in parallel would ,
(a) Reduce the overall value of résistance , *****
(b) Have no effect on the résistance compared to one conductor ,
(c) Double the résistance value of résistance ,
(d) Increase the overall value of résistance ,

(17) On a ring continuity test (R1 + R2 ) can be calculated by ,
(a) Adding line ( r1 ) and protective conductor ( r2 ) ,
(b) Subtracting ( r2 ) from ( r1 ) ,
(c) Adding ( r1 ) to ( r2 ) and dividing by ( 4 ) , **** ( Remember this if your doing your 2391-10 ) look back on these pages , it all there ,
(d) Adding ( r1 ) to ( r2 ) and multiplying by ( 4 ) ,

(18) Decreasing a conductor length with cause its résistance to ,
(a) Remain the same ,
(b) Vary ,
(c) Increase ,
(d) Decrease , *****

(19) Where cables are connected in parallel the overall insulation résistance ,
(a) Stay the same .
(b) Varies ,
(c) Increase ,
(d) Decreases ,

(20) Insulation résistance is measured in ,
(a) mΩ
(b) Ω
(c) KΩ
(d) MΩ

(21) Before carrying out an insulation résistance test consideration must be given to ,
(a) Client consultation , safety procedures and notices , *****
(b) Checking the results and verifying them ,
(c) The supply voltage and frequency ,
(d) Ze and PFC ,

(22) Before carrying out an insulation résistance test ,
(a) Carry out verification of voltage drop ,
(b) Ensure supply is switched on ,
(c) Contact local authority building control ,
(d) Safely isolate and consider electronic components and voltage sensitive equipment , *****

(23) When carrying out an insulation résistance test , tests should be between ,
(a) Live to Neutral and Live to Earth , ( Mac two Answers on sheet A / B ) ???????? Help ( Myself ( A ) Tutors for you ?
(b) Live to Live and Live to Earth ,
(c) Earth to Neutral and Earth to Earth ,
(d) Neutral to Neutral and Live to Earth ,

( A low resistance between phase and neutral conductors, or from live conductors to earth, will result in a leakage current. )

 

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(24) The required test voltage and minimum value of résistance for circuit above 50V to 500V is :
(a) 250v / 0.5mΩ ,
(b) 500v / 1MΩ , *****
(c) 250v / 1MΩ ,
(d) 500v / 0.5MΩ ,

(25) The insulation résistance test to verify separation between SELV circuits and other circuits should be ,
(a) 250v / 0.5mΩ ( table 61 regs ) *****
(b) 500v / 1MΩ
(c) 250v / 1MΩ
(d) 500v / 0.5MΩ

(26) A shower located in a room above a bath would be : ( regs 701.512.2 (ii ) in zone 1 – 2 : IPX4 , lighting bathroom ,
(a) In zone 0 , IP4X and not RCD protected ,
(b) In zone 1 , IPX4 and RCD protected , *****
(c) In zone 2 , IPX8 and not RCD protected ,
(d) In zone 0 , IPX8 and RCD protected ,
( anything that moves in bathroom RCD it 30mA ) 17th Edition ,
( Zone 1 : IPX4 , Zone 0 : IPX7 , Zone 2 : IPX4 , Electrical equipment exposed to water jets , e.g. IPX5 : ←←←

(27) The appropriate IP code for finger protection from contact with a Live terminal is ,
(a) IP2X , ***** ( how to remember Two Finger up , V )
(b) IP4X ,
(c) IPX2 ,
(d) IPX4 ,

(28) A polarity test is carried out to confirm ,
(a) RCD is in the Live side of the circuit ,
(b) Main double pole switch is in the Live side of the circuit ,
(c) Single pole switches , cable contact of Edison screw lampholders and fuses are in the Live side of the circuit , *****
(d) Double pole switches are in the Live side of the circuit ,

(29) Correct polarity of a final circuit can be confirmed during the ,
(a) Protective conductor continuity test ( R1 + R2 ) , *****
(b) Insulation résistance test ,
(c) External loop impedance test ,
(d) Protective fault current test ,

(30) Correct polarity is confirmed when supply is switched on to confirm ,
(a) Correct polarity of final circuit ,
(b) Correct polarity of final circuit and supply connections , *****
(c) Correct polarity of supply connections ,
(d) Correct polarity of portable equipment ,

(32 ) Earth electrodes’ can be tested using ,
(a) A voltmeter or ammeter ,
(b) A Insulation résistance tester or continuity tester ,
(c) An earth electrode or loop impedance tester , ***** ( Remember 2 Instrument’s Used , method 1 , method 2 , )
(d) An RCD tester or frequency meter ,

(33) When measuring earth electrodes’ using an earth fault loop impedance tester the tester should be connected ,
(a) To the furthest point ,
(b) To every socket outlet of the ring in turn ,
(c) To the installation supply with the main earthing conductor disconnected from the main earthing terminal , *****
(d) At mid point in a ring circuit ,

(34) A supply earthing arrangement which has a combined neutral and earth is a ,
(a) TN-S- system ,
(b) TN-C-S - system , ***** ( Look up in the regs , Definitions , p-33 )
(c) TT- system ,
(d) IT- system ,

(35) Earth fault loop impedance values for ( Zs ) is carried out ,
(a) At the supply ,
(b) At the first socket in a ring circuit and furthest lighting point in a lighting circuit ,
(c) At all consumer unit MCB outgoing terminals ,
(d) At all sockets in a ring circuit and furthest lighting point in a lighting circuit , *****

(36) A measured value of ( Zs ) can be compared with the maximum tabulated value by 0.8 ,
(a) Multiplying the tabulated value by 0.8 , ↔ ( Mac I could be wrong here I’ll stick my neck out ) Help !!!!!! A / D
(b) Multiplying the measured value by 0.8 ,
(c) Dividing the tabulated value by 0.8 ,
(d) Dividing the measured value by 0.8 ,

Ambient temperature at the time of test , and the maximum conductor operating temperature , both of which will have an effect
On conductor résistance , hence , the ( R1 + R2 ) could be greater at the time of fault than at the time of test ,
Our measured value of ( Zs ) must be corrected to allow for these possible increases in temperature occurring at a later date , this
Requires actually measuring the ambient temperature and applying factors in a formula ,
( which simply requires that the measured value of ( Zs ) does not exceed 0.8 of the appropriate tabulated value gives the 0.8 values of the tabulated loop impedance for direct comparison with measured values )
In effect , a loop impedance test places a Line / Earth Fault on the Installation ,
The value of ( Zs ) will have to be determined from measured values of ( Ze ) and ( R1 + R2 ) and the 0.8 rule applied ,

Note : Never Short out an RCD in Order to conduct this Test :
As a Loop Impedance test creates a high Earth Fault Current , albeit for a Short Space of time , some lower rated circuit breakers may operate , resulting in the same situation as with an RCD , and ( Zs )
Earth Fault Loop Path : Fault current , Exposed Conductive Path , TN-C-S ( Ze – 0.35Ω pen conductor ) TN-S ( Ze – 0.8Ω )

External Loop Impedance ( Ze )
The value of ( Ze ) is measured at the intake position on the supply side , and with all main protective bonding disconnected ,
Unless the Installation can be isolated from the supply , this test should not be carried out ,
As a potential shock risk will exist with the supply on and the main protective bonding disconnected ,

Additional protection RCD / RCBO operation :
Where RCDs / RCBOs are fitted it is essential they operate within set parameters , The RCD testers used are designed to do just this ,
Basic tests required are as follows :
(1) Set the Instrument to the rating of the RCD :
(2) Set the Instrument to half-rated trip :
(3) Operate the Instrument and the RCD , should “ Not trip “
(4) Set the Instrument to deliver the full rated tripping current of the RCD , ( I∆n )
(5) Operate the Instrument and the RCD , should trip out in the required time :
(6) For RCDs rated at 30mA or less set the Instrument to deliver ( x5 ) times the ratted current of the RCD , ( 5 I∆n )
(7) Operate the Instrument and the RCD , should trip out in ( 40mS )

( PS , I wont give up my day job )

(38) RCDs can be used for ,
(a) Overload protection of portable appliances ,
(b) Additional protection of socket outlets up to 20A , special locations’ and installations , *****
(c) Fault current protection of equipment and socket outlets rated above 32A
(d) Basic protection ,

(39) RCDs connected in series must have ,
(a) Delay operation facilities ,
(b) Indicator lamps of different colours ,
(c) One combined test button facility ,
(d) Discrimination between RCDs , *****

(43) Prospective fault current measurement ensures that ,
(a) Cables can carry the required load current ,
(b) The consumer unit main switch can be operated during a fault ,
(c) The over current protective devices at that point in the installation can disconnect the fault current , *****
(d) The main fuse will operate in the event of a fault ,

(45) The maximum permitted voltage drop to BS-7671:2008 for ,
(a) 4% lighting 4% other uses ,
(b) 9.2% lighting 4% other uses ,
(c) 2.5% lighting 4% other uses ,
(d) 3% lighting 5% other uses , ( Appendix 12 , p-358 ) *****

(46) The requirements for erection of electrical installations are given in ,
(a) Electricity at Work Regulations 1989 ,
(b) IEE On Site Guide ,
(c) Building Regulations ,
(d) BS-7671 :2008 , ***** ( regs chapter 52 : P-97 )

(50) Instruments used for electrical installation testing should be ,
(a) Calibrated on a regular basis , *****
(b) Exempt from calibration ,
(c) Calibrated after and initial verification ,
(d) When the batteries are dead ,

State the Recommended Sequence of Tests Covered by this Unit and the Reasons for that Sequence :

Sequence taken from BS-7671 : 2008 Part 6

………………….. Test …………………………………………….. Reason ………..
Continuity of protective conductors : R1 + R2 value , Metalwork & Effective IR testing
Continuity of Ring Final Circuit : R1 + R2 value , No Interconnected ring
Insulation Résistance : No Short-between Line , Neutral & Earth
SELV : No Connection between Low & Extra Low-Circuits
PELV No Connection between Low & Extra Low-Circuits
Electrical Separation : No Connection between Low & Extra Low-Circuits
Basic protection by barrier or Enclosure : No finger or other solid more than 1mm
Insulation / Impedance of Floors and Walls : Effectiveness of high Résistance / Impedance Location
Polarity : Switches , Fuses , breakers etc in live side of circuit
Earth Electrode Résistance : Resistive Contact of Electrode to Ground :
Earth Fault Loop Impedance : To meet final circuit disconnection time in event of fault :
Additional protection / RCD test : To ensue RCD operates in time in event of Fault or misuse :
Prospective Fault Current : To ensue protective devices can disconnect fault effectively :
Check of Phase Sequence : To ensue 3 Phase motors etc, rotate incorrect direction :
Functional Testing : To Test RCD test button , Switches , breakers , locks etc, operate
Verification of Volt Drop : To ensue voltage at load end is within required limits ,

 

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Insulation Resistance Testing: How and Why ? Our cousins Overseas : IEE :

How significant is insulation resistance testing ? Since 80% of electrical maintenance and testing involves evaluating insulation integrity, the answer is "very important." Electrical insulation starts to age as soon as it's made. And, aging deteriorates its performance. Harsh installation environments, especially those with temperature extremes and/or chemical contamination, cause further deterioration. As a result, personnel safety and power reliability can suffer. Obviously, it's important to identify this deterioration as quickly as possible so you can take the necessary corrective measures.
What is insulation resistance testing? Basically, you're applying a voltage (specifically a highly regulated, stabilized DC voltage) across a dielectric, measuring the amount of current flowing through that dielectric, and then calculating (using Ohm's Law) a resistance measurement. Let's clarify our use of the term "current." We're talking about leakage current. The resistance measurement is in megohms. You use this resistance measurement to evaluate insulation integrity.
Current flow through a dielectric may seem somewhat contradictory, but remember, no electrical insulation is perfect. So, some current will flow.
What's the purpose of insulation resistance testing? You can use it as:
• A quality control measure at the time a piece of electrical equipment is produced;
• An installation requirement to help ensure specifications are met and to verify proper hook up;
• A periodic preventive maintenance task; and
• A troubleshooting tool.
How do you perform an insulation resistance test? Generally, you connect two leads (positive and negative) across an insulation barrier. A third lead, which connects to a guard terminal, may or may not be available with your tester. If it is, you may or may not have to use it. This guard terminal acts as a shunt to remove the connected element from the measurement. In other words, it allows you to be selective in evaluating certain specific components in a large piece of electrical equipment.
Obviously, it's a good idea to have a basic familiarity with the item you're testing. Basically, you should know what is supposed to be insulated from what. The equipment you're testing will determine how you hook up your meghommeter.
After you make your connections, you apply the test voltage for 1 min. (This is a standard industry parameter that allows you to make relatively accurate comparisons of readings from past tests done by other technicians.)
During this interval, the resistance reading should drop or remain relatively steady. Larger insulation systems will show a steady decrease; smaller systems will remain steady because the capacitive and absorption currents drop to zero faster than on larger systems. After 1 min, you should read and record the resistance value.
When performing insulation resistance testing, you must maintain consistency. Why? Because electrical insulation will exhibit dynamic behaviour during the course of your test; whether the dielectric is "good" or "bad." To evaluate a number of test results on the same piece of equipment, you have to conduct the test the same way and under the relatively same environmental parameters, each and every time.
Your resistance measurement readings will also change with time. This is because electrical insulation materials exhibit capacitance and will charge during the course of the test. This can be somewhat frustrating to a novice. However, it becomes a useful tool to a seasoned technician.
As you gain more skills, you'll become familiar with this behaviour and be able to make maximum use of it in evaluating your test results. This is one factor that generates the continued popularity of analogue testers.
What affects insulation resistance readings? Insulation resistance is temperature-sensitive. When temperature increases, insulation resistance decreases, and vice versa. A common rule of thumb is insulation resistance changes by a factor of two for each 10 DegrC change. So, to compare new readings with previous ones, you'll have to correct your readings to some base temperature. For example, suppose you measured 100 megohms with an insulation temperature of 30 DegrC. A corrected measurement at 20 DegrC would be 200 megohms (100 megohms times two).
Also, "acceptable" values of insulation resistance depend upon the equipment you're testing. Historically, many field electricians use the somewhat arbitrary standard of 1 megohm per kV. The international Electrical Testing Association (NETA) specification Maintenance Testing Specifications for Electrical Power Distribution Equipment and Systems provides much more realistic and useful values.
Remember, compare your test readings with others taken on similar equipment.

The 17th Edition :

Limits this to : ( regs p-358 )
Voltage drop in Consumer’s Installations ,
The Voltage drop between the origin of an Installation and any load point should not be greater than the values in table 12A
Expressed with respect to the value of the nominal voltage of the Installation ,
The calculated Voltage drop should include any effect due to harmonic currents :

3% for lighting ,
5% for Other Uses ,
3% of 230 = 6.9v
3 x 230 ÷ 100 = 6.9v
5% of 230v = 11.5v
5 x 230 ÷ 100 = 11.5v

6% & 8% respectively are permitted for private supplies ,

Ring Final Circuit : GN-3 ( Dead Test ) 2392-10
Instrument : Set : on Ohms –

Under : “ Schedule of Test Results “ Circuit Loop Impedance Ω : ( Ring Final Circuits , Only Measured End to End ,

Line / Line : Little : r1 = 0.43Ω ( Measured End to End ) ↔ Big Copper Lower Résistance )
Neutral / Neutral : Little : r n = 0.42Ω ( Measured End to End ) ↔ Big Copper Lower Résistance )
Earth – Earth : Little : r2 = 0.73Ω ( Measured End to End ) ↔ Smaller C.S.A. ↔ High Résistance )

The Three Test Results can know be put Onto the “ Test Result Sheet “

Domestic Electrical Installation Certificate : “ Test Results “ > Circuit Impedance ( Ω ) :
( Ring Final Circuit(s) Only / Measured End–to–End , > Test Results in Box <

“ Résistance and the Conductor “ 2392-10

Résistance is directly proportional to Length and inversely proportional to “ C.S.A” simply this means that More Length > More Résistance ,
and Less Length > Less Résistance , Also the Greater the C.S.A. the Less the Résistance , and the Smaller the C.S.A. the Greater the Résistance

The Circuit Design why ? : Apprentices

Lighting circuits are almost always wired in Parallel - from strings of Christmas tree lights to the lights in your home - since adding another light to the parallel circuit does not affect the voltage reaching the lights already in the circuit. If for example you were to wire two 12V bulbs in series with a 12V battery, each bulb would receive only 6 Volts. Wired in Parallel each bulb still receives the 12 Volts it needs. Also, if one bulb fails, the rest of the bulbs will remain lit ,

Circuit Résistance in Parallel

Résistance is directly proportional to length and inversely proportional to c.s.a. Simply this means that more length, more Résistance, and less length less Résistance. Also the greater the c.s.a. the less the Résistance, and the smaller the c.s.a. the greater the Résistance.

 

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Amberleaf ( 6 – Pack Tonight )

Passed My 2392-10 Certificate / Fundamental Inspection , Testing & Initial Verification :

Have a lot off 2391-10 stuff , when I get a chance I’ll down load them ,

Jason I’ll need to use a new folder Amberleaf , how will I word it !!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Testing –

The Obtaining and Recording of the Installations ( Psc ) & ( Ze ) Details :

When Obtaining the Values of either the Psc & Ze at the Origin of the Installation three Methods appear to be Acceptable :

(1) By Enquiry : Usually given upon request to the local Regional Electricity Board , it is common practice for them to quote
A maximum value “ this usually being 16kA for the Prospective Short Circuit Current and earth loop values of 0.35Ω for TN-C-S 0.8Ω for a TN-S system , O.S.G. p-11

(2) By Calculation :
The Designer , using information given , with regard to cable sizing , length of run from the sub-station , etc , can calculate the (PSC ) & the Phase Earth Loop Impedance at the Origin of the Installation ,

(3) By Direct Measurement :
Using a Instrument a direct measurement can be made for the ( PSCC ) ↔ ( PFC ) & ( Ze ) of the Installation
at the Supply intake Terminals ,

* Test results do not specify whether the actual recorded instrument reading is that of a ( Phase / Neutral or a ( Phase / Phase short circuit ,
Although the worst scenario is a short circuit fault across the three phase it appears that a Phase / Neutral measurement is acceptable :

“ Measurement of the Prospective Earth Fault Current “
To measure the Earth Fault Current as a direct reading in Amps , the Instrument ( Neutral Lead can be Connected to the Earth Block )
with the Instrument still set on the current range what will now be measured is the Prospective Earth Fault Current ,

* ( Psc ) range kA ,
By Using this method it saves you having to divide the Earth Loop Impedance reading previously obtained into the supply voltage to
obtain the Earth Fault Current ,
Prospective Short Circuit Current to be measured and recorded , but where the Prospective Earth Fault Current exceeds that of the Short Circuit Current then this Value should be recorded in its place ,
the value of whichever is the Greater should be recorded on the Certificate as the Prospective Fault Current ( Pfc )

“ Measurement of the Short Circuit Current “
“ Range kA “
The test is made using a dedicated ( Psc ) Instrument connected as ( Line & Neutral )
( Most Earth Loop Impedance Instruments incorporate the facility for the measurement of the Phase-Neutral Prospective Short Circuit Current ,

The Protective Devices at the Point of Test must have a Short Circuit Rating in Excess of the reading taken ,
( the Exemptions from this Requirement are when MCBs etc. are used for Overload Protection and BS-1361 or BS-88
Protective devices with suitable operating Characteristics { POSITIONED on the SUPPLY SIDE ϟϟ }

Contractors will Only have Instruments capable of Psc measurement’s at 230V , so a problem will arise on Three Phase systems where a
Ph – Ph –Ph measurement is required , if a 3-Phase measurement is required it has unfortunately become common practice to multiply
The Single Phase recorded measurement by a factor of ( Ѷ 3 )
On Three Phase systems it should be policy to measure and record both the Three Phase Short Circuit Current ( Ph-Ph-Ph ) and
Single Phase Short Circuit Fault Current ,
( Unfortunately Obtaining the ( Ph-Ph-Ph ) Short Circuit Current is easier said than done ,

The Earth Fault Loop Impedance ( Zs ) is made up of the Impedance of the Consumers Phase & Protective Conductors ( R1 and R2 )
Respectively , and the Impedance external to the Installation ( Ze ) Impedance of the Supply ,
As the value of ( Ze ) will be obtained from the Electricity Company for the Initial assessment of the Installation ,
The maximum Impedance allowed for the Phase & Protective Conductors can be determined from :
( Zs + Ze + R1 + R2 )

Radial Circuit :
13Amp Immersion heater circuit protected by a Type B 16amp MCB , wired in 2.5mm2 PVC sheathed cable with a 1.5mm2 CPC
Supplied from 230 volt single phase TN-C-S system , what is the maximum length of run ? ( mV 19.51 x A 16 = 31.2m ) 2391 **

If = Uo / Zs : ( 230v Phase to Earth ) 230 ÷ 0.93Ω = 247A

Zs : R1 , 0.5Ω + R2 , 0.43Ω = 0.93Ω

 

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2392-10 Domestic Electrician’s ←←←←←←←←

-&- are asking for : ( Calculating of R1+R2 ) Calculating of MΩ in parallel , look back through the pages , Ps : Earth Electrode Calculating I got 9 off the this , BE AWARE ↔↔↔↔↔↔↔↔↔↔ Ambeleaf

 

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2392-10

i) Prospective Short Circuit Current is due to a Fault between Phases on Phase and Neutral :
ii) Prospective Earth Fault Current is due to a Fault between Phase and Earth :

i) Prospective Fault Current : intake position – house , ( PFC = 230 ÷ 0.2 = 1150.A / 1.15kA :
ii) Prospective Fault Current : complex “ Dist , Board “ ( PFC = 230 ÷ 0.46 = 500A / 0.5 kA :

Remember to look through your Cals on the pages , its your Butt on the Line , 2392-10 ←←←
You need to think like a Tester ,

 

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Visual Inspection 0nly :

Until an obvious fault develops, most householders appear to assume that their electrical installations are
safe, and will remain so forever. Even those who appreciate that electrical installations eventually need
to be checked appear reluctant to pay for a full BS-7671-style periodic inspection, except perhaps when
they are buying or selling a property. Therefore, even given the significant limitations of ‘visual inspection
only’ such inspection by a competent person can usefully serve to identify damage, deterioration and, to
some extent, defects, which might otherwise go unnoticed by those using the installations.

in principle, visual inspection of the electrical installation in a dwelling by a competent person is an important part of the assessment of the condition of that installation. Visual inspection can identify damage, deterioration and
some defects in installations. Given the potential benefits, the NICEIC does not consider the practice of ‘visual inspection only’ to be non-compliant with the requirements of BS-7671,
provided that:
The visual inspection is carried out by an electrically competent person with good knowledge and experience of the electrical

installation practices existing at the time the installation was first constructed.

* The inspection is carried out in accordance with all the requirements of BS 7671 that are applicable to visual inspection.
* The limitations of ‘visual inspection only’ are made clear in writing to the person ordering the work.
* No claim is made that ‘visual inspection only’ can or will fully determine whether an installation is safe for continued use.
* An objective report of the findings of the visual inspection is given to the person ordering the work, whether or not specifically requested by that person.
* The scope of the condition report includes all the aspects of the model periodic inspection report given in BS 7671 which are relevant to visual inspection.
* Visual condition reports do not include items that can only be checked with test instruments ( such as the adequacy of earthing arrangements ).
* Any quotation for proposed remedial work is given separately from the visual condition report.
*A full periodic inspection is recommended to the customer if it is suspected that the installation is in an unsafe condition.

 

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THE 17TH EDITION & LOCATIONS CONTAINING ….. ( 2392-10 )

A BATH OR SHOWER

INTRODUCTION
Section 701 of BS7671:2008 The 17th Edition is the new section covering locations containing a
bath or shower. The bathroom regulations Section 601 of the 16th Edition were based on the draft
international standard IEC 364. The 17th Edition has been based on both IEC 364 Section 701 and
the new European harmonised document HD 384 Part 7, within Section 701 of the 17th Edition.
HD 384, Section 701 has been published. The 17th Edition absorbs the regulations in these standards.
As with the 16th Edition, regulations in 701 are specific requirements that add to or modify the general
requirements of Parts 3, 4 & 5. The numbers following the section number relate to the chapter and
sections of the general parts e.g. 701.415.2 supplementary equipotential bonding is an extension of
section 415.2 in Chapter 41.
The scope of Section 701 is the same as the 16th Edition, any location where there is a fixed bath or
shower. This includes communal showers and baths in sports facilities and accommodation buildings,
hotels and similar as well as domestic bathrooms. It does not include emergency showers in industrial
areas or laboratories and medical treatment locations. However, there are no special requirements recorded for medical treatment locations. Electrical Contractors’ Association
KEY FACTSHEET
MAIN CHANGES
OMISSIONS FROM 16TH EDITION
601-01 Zone 3 is deleted.
601-04 Supplementary equipotential bonding is not required provided that all circuits at the location are
protected by a 30 mA RCD and there is continuity between the extraneous-conductive-parts and the
protective equipotential bonding.
601-07 Wiring systems is deleted.
There are no restrictions as to where cables may be installed but any surface enclosures, including
trunking, installed in the zones must have minimum rating IPX4.

ADDITIONS
701.411.3.3 Additional protection by 30 mA RCDs is required for all circuits serving equipment in the location.
701.512.3 Low voltage socket-outlets may be installed, but must be at least 3 m from the zone 1
boundary and protected by a 30 mA RCD.
701.753 Particular requirements for electric floor heating systems.

DETAILS OF REQUIREMENTS
ZONES
701.32.1 The upper height limit of all zones is 2.25 m. Above 2.25 m is outside of all zones.
701.411.3.3 ADDITIONAL PROTECTION BY RCDS
All circuits must be protected by RCDs. A single RCD may protect a group of circuits.

THE 17TH EDITION & LOCATIONS CONTAINING
A BATH OR SHOWER
INTRODUCTION
Section 701 of BS7671:2008 The 17th Edition is the new section covering locations containing a
bath or shower. The bathroom regulations Section 601 of the 16th Edition were based on the draft
international standard IEC 364. The 17th Edition has been based on both IEC 364 Section 701 and
the new European harmonised document HD 384 Part 7, within Section 701 of the 17th Edition.
HD 384, Section 701 has been published. The 17th Edition absorbs the regulations in these standards.
As with the 16th Edition, regulations in 701 are specific requirements that add to or modify the general
requirements of Parts 3, 4 & 5. The numbers following the section number relate to the chapter and
sections of the general parts e.g. 701.415.2 supplementary equipotential bonding is an extension of
section 415.2 in Chapter 41.
The scope of Section 701 is the same as the 16th Edition, any location where there is a fixed bath or
shower. This includes communal showers and baths in sports facilities and accommodation buildings,
hotels and similar as well as domestic bathrooms. It does not include emergency showers in industrial
areas or laboratories and medical treatment locations. However, there are no special requirements
recorded for medical treatment locations.

THE 17TH EDITION & LOCATIONS CONTAINING A BATH OR SHOWER
701.413 ELECTRICAL SEPARATION
May be used as a protective measure for a single item of equipment or a single socket outlet.
Not to be used with electric floor heating systems.

701.414 EXTRA LOW VOLTAGE - SELV OR PELV
All live parts to be insulated or contained within enclosures, minimum IPXXB or IP2X.

701.415 ADDITIONAL PROTECTION SUPPLEMENTARY EQUIPOTENTIAL BONDING

Where required, supplementary bonding shall connect protective conductors of each circuit to each other
and to accessible extraneous-conductive-parts. This includes: metal water, gas and waste pipes, metallic
air conditioning and heating systems, accessible structural parts of the building.
Metal door and window frames and similar are not normally extraneous-conductive-parts unless connected
to structural steel.
The bonding does not necessarily have to be in the location. It may be an adjacent room (linen cupboard)
or above a ceiling. It must be accessible for inspection, testing and maintenance.

SUPPLEMENTARY BONDING IS NOT REQUIRED AND MAY BE OMITTED:
(i) where main bonding is provided in accordance with 411.3.1.2, and
(ii) all final circuits meet the required disconnection times 0.4 sec for TN systems, 0.2 sec for TT
systems, and
(iii) all circuits have additional protection by 30 mA RCD, and
(iv) all extraneous-conductive-parts (metal water pipes) in the location are electrically continuous
and effectively connected to the protective equipotential bonding.
Where the main pipework of water distribution and central heating systems are pvc, short sections of
copper pipes connecting taps, radiators and the like are not considered to be extraneous-conductive parts
because they are unlikely to introduce Earth to the location. Supplementary bonding is therefore
not required.
Supplementary equipotential bonding is unlikely to be required on a new installation. It may be required
where alterations and additions are being made to an installation (it may already in place). In this
situation, circuits that are not being affected by the alterations do not require upgrading to meet the
requirements of 701.411.3.3 protection by 30 mA RCD.

701.5 SELECTION AND ERECTION OF EQUIPMENT, SWITCHGEAR AND CONTROLGEAR

701.512.2 EXTERNAL INFLUENCES
The following does not apply to the switches and controls of fixed current using equipment and the cords
of pull cord switches.
All equipment must be suitable for the zone in which it installed.
Requirement for equipment:
(i) Zone 0 - IPX7
(ii) Zones 1 & 2 IPX 4 (except in Zone 2, shaver sockets to BS EN 61558-2-5 located where
direct spray from showers is unlikely).
(iii) IPX5 anywhere where equipment may be exposed to water jets.
THE 17TH EDITION & LOCATIONS CONTAINING A BATH OR SHOWER
701.512.3 ERECTION OF SWITCHGEAR, CONTROLGEAR AND ACCESSORIES
(i) Zone 0 - no switchgear or accessories are permitted
(ii) Zone 1 - only switches for SELV circuits and equipment - max 12V a.c. rms or 30V ripple free
d.c. may be used. Safety source to be outside zones 0, 1 & 2.
(iii) Zone 2 as (ii) above except, shaver sockets to BS EN 61558-2-5 may be fitted.
(iv) 13 amp socket-outlets may be installed, must be at least 3 m from the zone 1 boundary.
13 Amp socket outlets may be
installed 3m horizontally from the
boundary of Zone 1 and must be
protected by a 30mA RCD
*Zone 1 if the space is accessible without the use of a tool.
Spaces under the bath accessible only with the use of a tool
are outside the zones.
OR SHOWER
701.55 CURRENT-USING EQUIPMENT
In zone 0 current-using equipment must
(i) comply with the relevant product standard
(ii) be suitable for use in Zone 0
(iii) installed to manufacturer’s instructions
(iv) be fixed and permanently connected
(v) SELV not exceeding 12 V a.c. rms or 30 V ripple-free d.c. Safety source to be outside Zone 0,1 & 2
In zone 1 current-using equipment must
(i) be fixed and permanently connected
(ii) be suitable for use in Zone 1
(iii) installed according to manufacturer’s instructions
Equipment that may be installed
(i) Whirlpool units
(ii) Electric showers
(iii) Shower pumps
(iv) Equipment protected by SELV or PELV nominal voltage not exceeding 25 V a.c. rms or 60 V
ripple-free d.c.
Safety source to be outside Zone 0,1 & 2
(v) Ventilation equipment
(vi) Towel rails

(vii) Water heaters
(viii) Luminaires
In zone 2 current-using equipment must be
(i) permanently connected, the means of connection must be outside of zone 2
(ii) suitable for use in a location containing a bath or shower
(iii) installed according to manufacturer’s instructions

701.753 ELECTRIC FLOOR HEATING SYSTEMS
Heating cables and thin sheet heating elements must:
(i) comply with relevant product standards
(ii) have a metal sheath, or
(iii) have a metal enclosure, or
(iv) be covered with a fine metal mesh.
Unless the protective measure SELV is applied, metal sheaths, enclosures and grids must be
connected to the circuit cpcs
The protective measure ‘electrical separation’ is not permitted

RCD Ratings :

The rating of an RCD has nothing to do with its ability to handle the current to the appliance or the circuit protected, but is the value of residual current at which it will operate. Thus, an RCD in a typical domestic situation may well be able to switch off the load current of 40A but be rated at a residual current of 30mA ( thirty thousandths of an ampere ). RCDs are made with a wide range of ratings, but by far the most common are 30mA and 100mA