Indian regulations in Electrical Safety P.Lahiri BARC

Indian regulations. Indian Electricity Act-1910. Repealed under section 185 of Electricity act -2003 Indian Electricity (Supply) Act- 1948. Indian Electricity Regulatory Commission Act-1998. The Electricity Act –2003. Indian Electricity Rules- 1956.

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.

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

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.

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

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

Electric shock and flash burn AERB14 Electric shock and flash burn

Occurrence of blast EXPLOSION AERB14A

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)

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

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)

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

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

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

LV,MV

11k,33k or

>33k

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

Above 1000kVA

Primary HV

630kVA

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.

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

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:-

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)

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.

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

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.

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

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

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)

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)

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

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

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)

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)

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)

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

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

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

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

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

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.

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)

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)

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

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.

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

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 5200 + 300 for every 33kV but not less than 6100

Clearance of overhead lines from building(Rule) Condition System voltage Minimum clearance in mm Vertical (IE R 79) LV, MV 2500 HV 3700 EHV 3700 + 300 for every 33kV Horizontal (IE R 80) 1200 HV upto 11kV HV above 11kV 2000 2000 + 300 for every 33kV

Section clearance SC SC SECTION CLEARANCE

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

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

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

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)

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.

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)

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.

Clearance across the road

Clearance along the road

Clearance anywhere else

Clearance from building Vertical clearance Horizontal clearance

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

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

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

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

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

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

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

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

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

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

Isolating clearance Isolating clearance

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.