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Electrical

Each year a large number of employees are injured or killed because they come into contact with energized electrical wiring or equipment. The Electrical Safety Orders (ESOs) are designed to control or to eliminate these often deadly exposures and include:

A. General requirements for low-voltage systems ( <= 600 V)

1. Only qualified persons may work on electrical equipment or systems. 2320.1(a)
   
2. Maintenance of electrical installations is required to ensure their safe condition. 2340.1
   
3. Electrical equipment and wiring must be protected from mechanical damage and environmental deterioration. 2340.26, 2340.11(a)(2), 2340.23
   
4. Covers or barriers must be installed on boxes, fittings, and enclosures to prevent accidental contact with live parts. 2340.17(a)
   

B. Main service equipment

Whenever the electric utility provides service via overhead lines, the installation must:

1. Consist of an acceptable service pole. 2405.3
   
2. Be suitably grounded. 2395.5(b)
   
3. Provide suitable over current protection. 2390.1
   

C. Wiring methods and devices

1. Flexible cords may be used in place of permanent wiring methods for temporary work if the cords are equipped with an attachment plug and energized from an approved receptacle. 2500.7(a),(b)
   
2. Flexible cords must be Type S and cannot be spliced unless they are size No. 12 (or larger). 2500.9(a)
   
3. Skirted attachment plugs must be used on all equipment operating at more than 300 V. 2510.7(b)
   

D. Grounding

1. Each receptacle must have a grounding contact that is connected to an equipment grounding conductor. 2510.7(a)
   
2. Temporary wiring must be grounded. 2405.2(g)
   
3. Powered tools and electrical equipment with exposed, non current-carrying metal parts must be grounded. 2395.45(b)

   Exception: Double insulated powered tools need not be grounded. 2395.45(b)

4. Generators rated greater than 5,000 V or multi-phase must be grounded. 2395.6(a)(4)

   Exception: A portable or vehicle-mounted generator need not be grounded if it is rated less than 5,000 V and single phase, provided that the grounding terminals of its receptacle are bonded to the vehicle frame, the generator frame, and to the plugged-in equipment. 2395.6(a)

E. Ground-fault circuit interrupters (GFCIs)

The GFCI device senses ground faults (accidental electrical paths to ground) in circuits and immediately cuts off all electrical power in that circuit.

1. GFCIs are required on receptacles that are not connected to the site’s permanent wiring and that have a rating of 15 or 20 amps., 120 V, AC, single phase. 2405.4(c)
   
2. The assured equipment grounding conductor program (AEGC program) is an approved alternative to the GFCI requirement if the following program elements are included: 2405.4(d)
   1. A description of the program must be written.
      
   2. The employer shall designate one or more qualified persons to implement the program.
      
   3. Daily visual inspection of included equipment must be conducted.
      
   4. The following tests shall be performed:
      
      1. All equipment grounding conductors shall be tested for continuity and shall be electrically continuous.
      2. All plugs and receptacles must be tested for proper attachment to the equipment grounding conductor.
   5. The tests shall be performed as follows:
      
      1. Before the first use of newly acquired equipment
         
      2. Before equipment is returned to service
         
      3. Before equipment is used after an incident that may have caused damage
         
      4. At intervals not to exceed three months
         
   6. The employer shall not make available or permit the use of equipment that has not met the requirements of 2405.4(d).
      
   7. A means of identifying tested equipment shall be provided.
      

1. Great care must be taken when working or operating equipment near overhead high-voltage power lines.
   
2. The required minimum safe distances (clearance) from overhead lines energized by 600 V to 50,000 V are: 2946
   
   1. For boom-type equipment in transit, 6 ft.
      
   2. For boom-type equipment in operation, 10 ft.
      
   3. For people working near overhead lines, 6 ft.

      Note: See 2946 for minimum required clearances from voltages greater than 50,000 V.

3. The following activities are prohibited unless overhead power lines have been de-energized and visibly grounded:
   
   1. Work over high-voltage lines. 2946(b)(1)
      
   2. Work within required clearances. 2946(b)(2)

      Note: When work is to be performed within minimum required clearances, the power line operator must be notified. 2948

G. High-voltage warning signs. 2947

High-voltage warning signs must be posted in plain view of equipment operators.

H. Lock-out procedures

Lock-out procedures must be followed during the cleaning, servicing, or adjusting of machinery. GISO 3314, ESO 2320.4