1. Indian regulations in Electrical Safety
P.Lahiri
BARC

2. Indian regulations. Indian Electricity Act-1910.
Repealed under section 185 of Electricity act -2003
Indian Electricity (Supply) Act
Indian Electricity Regulatory Commission Act-1998.
The Electricity Act –2003.
Indian Electricity Rules

3. Objectives of regulations
Make generation, transmission, distribution and utilization of electricity as safe as possible.
Identification of different categories of agencies.
Remove ambiguities from existing qualitative guidelines and pronounce precise quantitative technical requirement with respect to safety.

4. Categories of agencies
Supplier of electricity.
Consumer of electricity.
Electrical inspector.
Electrical contractor and supervisors.
Authorized persons.  

5. Hazards of electricity
Electric shock:- Current flows through body or part of body when two surfaces having electrical potential difference is touched resulting in burn, disability or even death.
Flashover:-Sudden collapse of electric field by having a conducting path between two electrical potential different surfaces resulting in burn, fire.
Blast:-Failure of dielectric medium between two electrical potential different surfaces resulting in projectile, mechanical force, fire or burn.
Heat:-Caused by loose connection in the circuit, overheating of insulation/ conductor due to overload or prolonged short circuit current etc. resulting in fire, burn.

6. Quantitative effect of electric current (up to 3sec
Quantitative effect of electric current (up to 3sec.) on human (source Daziel)
Effect mA
d.c
a.c
60Hz
10kHz M F
Perception threshold
5.2
3.5
1.1
0.7 12 8
Shock but not painful 9 6
1.8
1.2 17 11
Muscular control lost, breathing difficulty. 90 60 23 15 94 63
Ventricular fibrillation
500
100

7. Flash and flame burn
Thermal burns, Current flows typically external, Damage to skin

8. Electric shock and flash burn
AERB14
Electric shock and flash burn

9. Occurrence of blast
EXPLOSION
AERB14A

10. Classification of rated voltage as per IE rule
Extra High Voltage (EHV)
Above 33kV
33kV
High Voltage (HV)
650V
Medium Voltage (MV)
250V
Low Voltage (LV)

11. Authorization Avoid chaos Fixing up of responsibility
Electrical isolation.
Identification & display.
Restriction of access.
Inspection, testing etc.
Preparedness for adversity.
Other hazard precaution.
Protection & interlocks.
Clearances.
Earthing.
Reporting accidents.
Avoid chaos
Fixing up of responsibility
Ensures expertise

12. Authorization rule Requirement Applicable for Rule
Work to be executed by licensed electrical contractor.
All new, addition, alteration jobs having electrical scope except minor jobs.
45-(1), (3)
Safety officer to be authorized by owner with approval of electrical inspector.
Electrical installation with more than 250kW connected load
3, 4, 5, 6
Prior approval from electrical inspector to work
Any electrical work on live apparatus/ line
36 (2)

13. Authorization cntd. Qualifications rule
Agency
Minimum qualification
Rule
Authorized O & M person for generating station of capacity above 100MW and sub-stations of 132kV and above.
Second class diploma in mechanical or electrical engineering & training from CEA approved institute.
3 (2A)
Assistants to above
ITI & training from CEA approved institute

14. Electrical isolation. Quick de-energization
Authorization.
Electrical isolation.
Identification & display.
Restriction of access.
Inspection, testing etc.
Preparedness for adversity.
Other hazard precaution.
Protection & interlocks.
Clearances.
Earthing.
Reporting accidents.
Quick de-energization
Ensure de-energization while on work

15. Electrical isolation(Rule)
Rating of service connection
Isolation device
Rule CB
SFU*
LV, MV service connection 
50-(b) (i) (ii)
upto 1000kVA at 11kV
Above 1000kVA at 11kV 
upto 2500kVA at 33kV
Above 2500kVA at 33kV
Any rating beyond 33kV

16. LV,MV

17. 11k,33k or

18. >33k

19. Electrical isolation device for transformers (Rule)
Rating of transformer
Isolation device
Rule
Pri:
Sec: CB
SFU*
Upto 630kVA and primary side less than HV 
50-(b) (i) (ii)
upto 630kVA and primary side HV and above. 
630kVA to 1000kVA irrespective of primary voltage
Above 1000kVA irrespective of primary voltage

20. Above 1000kVA

21. Primary HV

22. 630kVA

23. Identification & display
Authorization.
Electrical isolation.
Identification & display.
Restriction of access.
Inspection, testing etc.
Preparedness for adversity.
Other hazard precaution.
Protection & interlocks.
Clearances.
Earthing.
Reporting accidents.
Electricity is invisible:-
Various current carrying portions
Different circuits/ phases/ a.c/ d.c. etc.
Different voltages LV,HV,MV etc
Power flow directions.
ON/OFF positions and direction of operation of SFUs/CBs/Isolators.
Source locations of PCCs/ MCCs and load locations of each feeders of MCCs
Danger notices.

24. Identification & display (Rule)
Requirement
Applicable for
Rule
Display of danger notice.
Electrical installation rated MV and above. 35
Visual identification by distinct colour.
All conductors connected to earthing system
32(1)
Visual distinction of circuits, voltages, feeders etc.
All electrical installation 41

25. Restriction of access Thwart accidental or unauthorized access:-
Authorization.
Electrical isolation.
Identification & display.
Restriction of access.
Inspection, testing etc.
Preparedness for adversity.
Other hazard precaution.
Protection & interlocks.
Clearances.
Earthing.
Reporting accidents.
Thwart accidental or unauthorized access:-

26. Restriction of access (Rule)
Requirement
Applicable for
Rule
Metallic covering which is electrically and mechanically continuous
All live conductors for indoor installations.
51(1)(a)
Metallic fencing of height not less than 1.8M.
Out door sub-station.
68(b)

27. Inspection testing & maintenance
Authorization.
Electrical isolation.
Identification & display.
Restriction of access.
Inspection, testing etc.
Preparedness for adversity.
Other hazard precaution.
Protection & interlocks.
Clearances.
Earthing.
Reporting accidents.
Ensure adequacy of safety related parameter:
Maintaining safety related parameter within limit.

28. Commissioning inspection (Rule)
Type of Installation
Type of test (Rule do not specify) interpreted.
Inspecting authority
Any installation upto MV (not generating plant)
Visual inspection.
Insulation resistance.
High voltage.
Earth resistance.
Any functional requirement.
Supplier.
Generating plant of capacity less than 10kW
Same as above
Owner

29. Commissioning inspection (Rule) cntd.
Type of Installation
Type of test (Rule do not specify) interpreted.
Inspecting authority
Generating plant of capacity more than 10kW
Depending upon voltage level as desired by Electrical Inspector
Electrical Inspector.
HV or EHV installation
Visual inspection, insulation resistance, high voltage, earth resistance, functional tests and test as desired by Electrical Inspector.

30. Periodic inspection (Rule)
Type of test
Maximum time interval.
Record keeping duration
Test by inspector
5 years
Not specified
Earth resistance for LV and MV installation
2 years
2 years.
Earth resistance for HV and EHV installation
1 year
2 year
Fire extinguishers

31. Preparedness. Mitigate the effect of fast acting electrical disaster
Authorization.
Electrical isolation.
Identification & display.
Restriction of access.
Inspection, testing etc.
Preparedness for adversity.
Other hazard precaution.
Protection & interlocks.
Clearances.
Earthing.
Reporting accidents.
Mitigate the effect of fast acting electrical disaster
Ensure correct course of action

32. Preparedness (Rule) Essential Applicable for Rule
First-aid box, Restoration chart, Fire buckets
Every generating station, enclosed sub-station and enclosed switch station
43(2), 44(1), 43(1)
Two or more gas masks
1.Generating station with capacity of 5MW and above
2.Enclosed sub-station with transformation capacity of 5 MVA and above
43(3)

33. Preparedness (Rule) cntd.
Essential
Applicable for
Rule
Artificial respirator
Every manned high voltage or extra-high voltage generating station, sub-station or switch station
44(4)
Trained personnel for providing artificial respiration.
All attended generating station and sub-station.
44(3)

34. Possibility of success of artificial respiration source Edition Electric Institute resuscitation manual

35. Other hazard precaution.
Authorization.
Electrical isolation.
Identification & display.
Restriction of access.
Inspection, testing etc.
Preparedness for adversity.
Other hazard precaution.
Protection & interlocks.
Clearances.
Earthing.
Reporting accidents.
Reduce potential initiating events of accident

36. Other hazard precaution.(Rule)
Situation
Safety measure
Rule
Electrical installation in explosive atmosphere
Explosion proof/ dust tight depending upon the hazardous zone as per IS5571
51(d)
Multistoried building with height more than 15M.
Power cable ducts shall not be used for other services
Power cable ducts shall have fire barrier at each floor crossing
50A-(4)

37. Other hazard precaution.(Rule) cntd..
Situation
Safety measure
Rule
Electrical installation with more than 2000litres of oil
Baffle wall of 4hr fire rating between single phase banks and on consumer premise.
Oil soak pit for full quantity of oil
64(2)-(e)
Electrical installation with more than 9000litres of oil
Measures mentioned above.
Fire extinguisher.
Oil draining arrangement.
64-(2)(e)

38. Other hazard precaution.(Rule) cntd..
Situation
Safety measure
Rule
Substation and switch station in the basement
Entrance shall have 2hr fire rating fire resistance door
A curb at entrance to trap oil flow.
Direct access to transformer from outside
Transformer protection by automatic HVWSp/ CO2/ BCF/ BTM/ N2 injection and drain.
64-(2) (f)-(ii)

39. Other hazard precaution.(Rule) cntd.. Location based on oil inventory
Total oil quantity in litre (includes transformer and other apparatus)
Location
Rule
Indoor
Out-door
Indl: building
Res:/ com: bldg. Any floor of
1st Bs.
Gr. Fl.
Other floors
No oil. 
64 (2)
2000 or less 
2000 to 9000
9000 or more

40. Protection & interlocks.
Authorization.
Electrical isolation.
Identification & display.
Restriction of access.
Inspection, testing etc.
Preparedness for adversity.
Other hazard precaution.
Protection & interlocks.
Clearances.
Earthing.
Reporting accidents.
Avoid human errors

41. Transformer protection
Rating
Mandatory relay protection
Remark
Less than 630kVA and primary side less than HV
No relay based protection is mandatory
Not specified
Less than 630kVA and primary side more than HV
Over current/ short circuit relay etc for secondary CB.
Not specified but implied by R50(b)(ii)
630kVA to 1000kVA

42. Transformer protection cntd..
Rating
Mandatory relay protection
Remark
1000kVA to 10MVA
Bucholz
Winding temp:
Oil temp:
R64(2)
More than 10MVA
Differential

43. HV & EHV installations interlocks
Situation
Preventive interlock
Rule
Isolator and CB in series
Isolator operation not allowed when CB is closed.
64 (A) (1)
Earthing switch and isolator
Earthing switch can not be closed when isolator is closed
Two or more incomer feeders to a bus bar but not intended for parallel operation
Only one feeder can be switched on at a time

44. HV & EHV installations interlocks cntd..
Situation
Preventive interlock
Rule
Two or more transformers in parallel
Secondary CB trips if primary of that transformer trips.
64 (A) (1)
Doors or gates give access to live parts
Doors can not be opened when any part is live.
Neutral switching device between neutral and earthing is used for generator
GCB can not be closed when neutral breaker is open.

45. HV & EHV installations protection
Protection against.
Type of relay
Mandatory for
Rule
Over current.
Over current/ short circuit relay.
Any Equip., cable supply line etc.
64A (2)
Rising touch potential.
Earth leakage/ earth fault.
Generator rated over 100kVA
Internal fault.
Differential relay
Generator rated over 1MVA Bus bars rated over 200kV
Switching over voltage/ lightning
Lightning arrestor
Overhead line terminations
92(1)

46. Other protections Protection for. Type of relay Mandatory for Rule
Human safety.
ELCB/ RCCB/ etc.
Any installation having connected load more than 5kW at MV or above
61A
DC earthing.
Over current relay between earthed middle conductor and earth.
DC three wire system
61 (1) (d) (i)

47. Time/ Current for a.c 50Hz
mSec
AERB9
50H a.c current (rms mA)
Zone 1- Usually no reaction, Zone 2 – Reaction may occur but usually no patho- psychological dangerous effect, Zone 3- No risk of fibrillation, Zone 4- Fibrillation possible (50% probability), Zone 5- Unsafe or fibrillation

48. Clearances (physical spacing)
Authorization.
Electrical isolation.
Identification & display.
Restriction of access.
Inspection, testing etc.
Preparedness for adversity.
Other hazard precaution.
Protection & interlocks.
Clearances.
Earthing.
Reporting accidents.
Minimum air insulation clearance.
Minimum space to work.
Minimum space for escape.

49. Clearances for bare conductor other than overhead lines(Rule)
Voltage
Section clearance (outdoor) in m.m.
Ground clearance (outdoor) in m.m
Rule
Upto 11kV
2600
2750 64
33kV
2800
3700
66kV
3000
4000
220kV
4300
5500
400kV
6500
8000

50. Clearance above ground of overhead lines across/ along a street (Rule)
Condition
System voltage
Clearance in mm
Rule
Across
LV, MV
5800 77 HV
6100
Along
5500
Any where else
LV, MV, HV (upto11kV)
4600
HV(above 11kV)
5200
Every where
EHV
for every 33kV but not less than 6100

51. Clearance of overhead lines from building(Rule)
Condition
System voltage
Minimum clearance in mm
Vertical
(IE R 79)
LV, MV
2500 HV
3700
EHV
for every 33kV
Horizontal
(IE R 80)
1200
HV upto 11kV
HV above 11kV
2000
for every 33kV

52. Section clearance SC SC
SECTION CLEARANCE

53. Ground clearance
Height of tall man’s raised finger tip with raised hand-2.5m GC
GROUND LEVEL
GROUND CLEARANCE

54. Earthing system. Limit touch potential Limit step potential
Authorization.
Electrical isolation.
Identification & display.
Restriction of access.
Inspection, testing etc.
Preparedness for adversity.
Other hazard precaution.
Protection & interlocks.
Clearances.
Earthing.
Reporting accidents.
Limit touch potential
Limit step potential
Safe predefined passage for fault current
Facilitate detection of incipient fault
Reduce neutral shifting

55. Step & Touch potential Et F
E/X CURVE Es E
Earth Mat 1M
0.5M X

56. Earthing (Rule) Requirement Applicable for Rule
Earthing terminal by Supplier.
LV consumer 33
Separate earthing terminal by supplier and consumer.
MV and above
Minimum two independent and redundant path with two earth electrode.
Earthing network for equipment, system.
R61(2), R61(3), R51(1)(b), R67(1)
All metallic part not intended to serve as conductor shall be earthed.
All electrical apparatus
Grounding of neutral.
a.c electrical power supply system more than 125V
61(1)(a), 64(3)

57. Reporting of accidents
Authorization.
Electrical isolation.
Identification & display.
Restriction of access.
Inspection, testing etc.
Preparedness for adversity.
Other hazard precaution.
Protection & interlocks.
Clearances.
Earthing.
Reporting accidents.
Reporting for analysis.
Fast reporting prevents suppression of facts.

58. Reporting of accidents (Rule)
Type of accident
Report format
Maximum period for reporting
Rule
Fatal involving loss or injury
Telegraphic
and
24hours
44A
Written
48hours
Failure of transformer or reactor above 20MVA
65(8)

59. Conclusion Regulations can induce more concern.
Regulations can not rule out accidents by themselves
Every concerned individuals should handle electricity in safe manner
Do not try to find out loopholes of regulation to limit our responsibility.
Try to adopt a proactive approach by understanding the intentions of the regulation authors.
In case of doubt ask electrical inspector or Central Electricity Authority.

61. Clearance across the road

62. Clearance along the road

63. Clearance anywhere else

64. Clearance from building
Vertical clearance
Horizontal clearance

65. Fire barrier in cable duct
Fl-4
Cables
Fl-2
Fire barrier
Fl-1
Electrical service shaft

66. Ground clearance for bare conductor other than overhead lines(Rule)
Voltage
Clearance in mm Outdoor
Upto 11kV
2750
33kV
3700
66kV
4000
220kV
5500
400kV
8000
Height of tall man’s raised finger tip with raised hand-2.5m

67. Phase to Phase(Rule) Voltage Clearance in mm Outdoor Ph~Ph Ph~E Sec:
Ground
11kV
460
33kV
915
66kV
1220
220kV
3350
400kV
4000

68. Phase to earth(Rule) Voltage Clearance in mm Outdoor 11kV 305 33kV 610
750
220kV
1675
400kV
3500

69. Clearances
It denotes the minimum distance in air between two potentially different points (this includes earthed/ ground surfaces) to avoid flashover during normal and transient over voltage.
Phase to earth
Minimum distance between live conducting parts and neighboring earthed parts.
Phase to earth

70. Clearances Phase to earth Phase to Phase
It denotes the minimum distance in air between two potentially different points (this includes earthed/ ground surfaces) to avoid flashover during normal and transient over voltage.
Phase to earth
Phase to Phase
Minimum distance between live parts of different phases.
Phase to phase

71. Clearances Phase to earth Isolating clearance
It denotes the minimum distance in air between two potentially different points (this includes earthed/ ground surfaces) to avoid flashover during normal and transient over voltage.
Phase to earth
Isolating clearance
Minimum distance between two sides of an open isolator
Phase to Phase
Isolating clearance

72. Clearances Section clearance Phase to earth
It denotes the minimum distance in air between two potentially different points (this includes earthed/ ground surfaces) to avoid flashover during normal and transient over voltage.
Section clearance
Minimum distance between maintenance zone and nearest live part plus one stretched arm length of a person
Phase to earth
Phase to Phase
Isolating clearance
Section clearance

73. Clearances Phase to earth Ground clearance
It denotes the minimum distance in air between two potentially different points (this includes earthed/ ground surfaces) to avoid flashover during normal and transient over voltage.
Phase to earth
Ground clearance
Minimum distance between lowest point of support insulator and ground
Phase to Phase
Isolating clearance
Section clearance
Ground clearance

74. Phase to earth & phase to phase clearance
TOWER
GANTRY
PH-TO PH
PHASE
TO EARTH
CLEARANCES IN OUTDOOR
STRUCTURE
P-E rule
P-P rule

75. Isolating clearance
Isolating clearance

77. Safety provisions in IE Rules
Authorization.
Electrical isolation.
Identification & display.
Restriction of access.
Inspection, testing etc.
Preparedness for adversity.
Other hazard precaution.
Protection & interlocks.
Clearances.
Earthing.
Reporting accidents.