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– Ensure the Electrical installation/electrical system meet codes and regulations.
– Conduct inspections to identify electrical safety deficiencies.
– Provide training for qualified.
– Report electrical deficiencies immediately.
To make an electrically safe workplace, the source side to load end shall be safe. For explaining the safe electrical system I will discuss
– Information of electrical system
– Condition of the electrical system
– Maintenance and inspection program of the electrical system
– Lightning protection system
– Earthing system
– Emergency power system
– Worker training
– Lockout/Tag out
– Personal Protective Equipment
Condition of Electrical System & Must Need to Follow
Overhead Service
-
- Covered conductor.
- Goose neck bend at the top shall be used.
Energy Meter
-
- Accessible to the authority.
- Convenient height.
- Protective cover except for the glass window.
- It shall not be installed less than 1m above the ground.
Sub-station
-
- The separate substation for load more than 50 K W.
- Considering 80% load factor except requirements of future expansion.
Location
-
- Multi-storied building: lowest floor level.
- Building complex/group of the building belonging to the same organization: separate building with adjacent to the generator room.
- The basement floor shall be avoided.
- The floor level shall be above the highest floor level of the locality.
- Suitable arrangements shall exist to prevent the entrance of storm or flood water into the sub-station area.
- The minimum height of a substation room should be 3.0m to 3.6m depending upon the size of the transformer.
- Need proper stair (where required) at the entrance.
- Foreign utilities (wet pipes) are prohibited.
- The room shall be proper fire rated.
- Required firefighting equipment must be kept.
- The substation room shall be properly illuminated.
- Need proper room partition.
- Need proper ventilation.
- The minimum area of the substation room with different transformer size is listed below;
|
Capacity of transformer (KVA) |
Transformer room area (m2) |
Total sub-station area (with HT, LT panels & transformer room but without generator) |
|
1 x 150 |
12 |
42 |
|
1 x 250 |
13 |
45 |
|
2 x 250 |
26 |
90 |
|
1 x 400 |
13 |
45 |
|
2 x 400 |
26 |
90 |
|
3 x 400 |
39 |
135 |
|
2 x 630 |
26 |
90 |
|
3 x 630 |
39 |
135 |
|
2 x 1000 |
26 |
90 |
|
3 x 1000 |
39 |
135 |
-
- Sub-station room shall be clean and free from dirt, lint, water, oil, combustible material and debris.
- Instruction board for first aid and artificial respiration shall be located.
- Must have adequate security.
- Required equipment and safety signage are needed.
- All equipment in the substation room is efficiently earthed.
Transformer
-
- Stormwater shall not enter the transformer.
- The transformer shall not install on a combustible base.
- The oil quality, silica gel should be checked on a regular observation basis.
- The transformer shall be lint, dirt combustible free. Otherwise, it may cause a fire.
- The upper-lower part of rod-gap arresters shall be aligned.
- Two-hour fireplace rating unless in an exceedingly high rise building.
- Four-hour fireplace rating if in an exceedingly high rise building.
- The transformer shall be installed in a separate room with a fire-rated wall and door.
- Border with the lockable arrangement.
Boiler Room Requirements
-
- The volume of the room for housing central heating boilers shall be at least 16 times the total volume of the boiler.
- Any area or area housing boilers or alternative heat manufacturing instrumentality shall be separated from alternative areas by a minimum one-hour construction or by a minimum special separation of 3m (10 ft) wherever set exterior to the building.
Other Safety Factors
-
- Proper and regular maintenance must be done.
- The boiler should not be operated beyond its certified steam pressure.
- Boiler logs must keep in a boiler room and should maintain properly.
- LT/MDB/DB/SDB/SB/MCB, MCCB box/others:
Location: Sub-distribution boards shall be located as close as possible to be electrical load centers.
Requirements: Distribution boards shall be installed within 2m from floor level.
Recommended Enclosure Sizes for MCB’s and Fuses:
|
Dimension in mm |
No. of MCBs or Fuses |
||
|
Height |
Width |
Depth |
|
|
350 |
390 |
120 |
Up to 12 |
|
480 |
390 |
120 |
Up to 24 |
|
610 |
390 |
120 |
Up to 36 |
|
740 |
390 |
120 |
Up to 48 |
-
- Switchboards and/or distribution boards shall be metal enclosed with dead front construction.
- Require at least 1m clearance in front of the panel board.
- The distribution board shall not be erected above gas stoves or sink or within 2.5m of any washing unit in the washing room or laundries.
- Adequate illumination shall be provided.
- Panel boards shall be properly grounded (earthed)
- Panel boards shall be properly identified.
- List and diagram shall be available.
- The circuit must be drawn with a protective device.
- Each circuit must have adequate ECC & neutral (if applicable)
- Meters and other electrical devices need to be installed at the main DB.
- Instruction of first aid & artificial respiration shall be kept near DB.
- The color code of cable/wire shall be maintained.
- Color code rules:
|
Single Phase |
Three Phase |
|
|
Phase Conductor (Line) |
Red or Yellow or Blue |
Line 1 Red Line 2 Yellow Line 3 Blue |
|
Neutral Conductor |
Black |
|
|
Protective Conductor (Earth) |
Green and Yellow |
|
-
- Cable color code is for the identification of conductors used in electrical installations.
|
Single Phase |
Three Phase |
|
|
Phase Conductor (Line) |
Brown |
Line 1 Brown Line 2 Black Line 3 Grey |
|
Neutral Conductor |
Blue |
|
|
Protective Conductor (Earth) |
Green and Yellow |
|
-
- Switchboards and/or distribution boards shall be free of combustible material, dirt and debris at near and inner side.
- Indications of overheating, overloading, of signs of burning shall be remediated.
- At least one spare circuit must be allowed in the distribution board for every five circuits in use.
- Sockets and Lights shall be used in a separate circuit.
- No higher rated circuit breakers with lower-rated wiring are acceptable.
- All metal in the building shall be connected to the building earthing/ground system.
- Junction boxes and other electrical devices shall be provided with covers.
- Mechanical guards shall be provided for electrical equipment and wiring where necessary.
- For building over six-story or 20m high, service shaft is required.
- Bunching cable/wire not allowed.
- Looping not allowed.
- Phase separators must be provided between terminals on circuit breakers.
- Electrical wiring and conduit shall be properly supported.
- A cable socket/lug shall be used.
- Splicing joint not allowed.
- Wire in the panel shall be dressed.
- Proper terminal connectors shall be used.
- Cable trenches shall be properly covered.
- Sufficient and graded rubber (insulation) mat shall be kept in front of the panel.
- Ceiling rose shall be used to connect tube light and fan.
- Electrical handheld tools shall be in good quality.
- Power and telecommunication cables shall be led separately.
- Normal DB, light etc not allowed in the chemical room.
Lightning Protection of Building
Whether a building needs protection against lightning depends on the probability of a stroke and an acceptable risk level.
Earthing System
Two separate and distinct earthing connections are required for
-
- Generator frame
- Motor
- Transformer
- Energy regulating apparatus
- Energy consuming apparatus
- Metallic pipe
- Metallic shed etc.
Maintenance and Inspection Program
Regular inspection and maintenance program shall be carried out for assuring proper installation. Some requirements are:
-
- Periodical inspection and testing.
- Periodical Inspection Resistance test (IR test).
- Electrical switchgear annual basis inspection. Earth Resistance test (ER test).
- Earth electrode resistance shall not exceed 1.
- Calibration/validation of all type of meters.
- Load measurement.
- The transformer oil analysis shall be routinely completed.
- Proper training.
- Thermo graphic scans and hot point remodification.
- Electrical measurement meters: Digital Multimeter, Clamp Meter, Insulation Tester, Earth Resistance Tester, Thermal Imager.
