Appendix E. FABRICATION AND MAINTENANCE PRACTICES

Design and construct equipment to protect personnel. First-line and backup safeguards should be provided to prevent personnel from accessing energized circuits. Establish periodic tests to verify that these protective systems are operative.

E1. Equipment Acceptability

Electrical equipment is considered safe only when it is used as specifically intended by its listing and design. Equipment must not be altered beyond the original design intent, and must not be used for any purpose other than that for which it was constructed.

Any equipment that is being recommissioned must be examined and/or tested, as appropriate, to verify the status of all safety features and the integrity of construction.

• Electrical equipment should be listed or labeled by a Nationally Recognized Testing Laboratory (NRTL).
  
• The division responsible for the equipment must maintain all documentation pertaining to the design safety features of the equipment, including any test data. This documentation must be available to any safety inspector.
  
• The inspector may require that equipment that is not NRTL-listed undergo inspection and/or testing for conformance to standards. Such testing should be documented and submitted to EH&S for approval. The inspection record must specify, at minimum:
  
• Equipment identification;
  
• Evaluator name, date, mailstop, and extension;
  
• Standard to which equipment is being evaluated;
  
• Specific tests, results, and areas of examination;
  
• Any conditions of product acceptability or limitations of use.

E2. Equipment Safety Practices

• Cable Clamping: A suitable mechanical-strain-relief device such as a cord grip, cable clamp, or plug must be used for any wire or cable penetrating an enclosure where external movement or force can exert stress on the internal connection. Grommets, adlets, or similar devices must not be used as strain relief.
• Emergency Lighting: Make emergency lighting available in case normal lighting fails when work is being conducted on energized components. (Emergency lighting is not necessary for Class 1A and 1B work. See Hazard Class Charts in Sections 8.7.3.1 and 8.7.3.2).
• Flammable and Toxic Material Control: Keep the use of flammable or toxic material to a minimum. A catch basin or other approved method must be provided to prevent the spread of these materials should the normal component case fail.
  
• Isolation: Isolate all sources of dangerous voltage and current with covers and enclosures. Access to lethal circuits (greater than 50V) must be either via screw-on panels (each containing no fewer than four screws or bolts) or via interlocked doors, panels, covers, etc. The frame or chassis of the conductive enclosure must be bonded  to  electrical ground with a conductor capable of handling any potential fault current.
  
• Lighting: Provide adequate lighting for easy visual inspection.
  
• Disconnecting Means and Overload Protection: Provide overload protection and well-marked disconnects. Local “off” controls must be provided on remote-controlled equipment.
  
• All disconnects and breakers must be clearly labeled to identify the loads they control.
  
• Power: All ac and dc power cabling to equipment not having a separate external ground but having line-to-line or line-to-ground voltage greater than 50V must have an equipment-grounding conductor unless cabling is inside an interlocked enclosure, rack, grounded wireway, or conduit, or feeds a commercial double-insulated or UL-listed ungrounded device. If the grounding of equipment introduces a greater hazard, the equipment must not be grounded.
  
• Rating: Operate all conductors, switches, resistors, etc., within their design capabilities. Pulsed equipment must not exceed either the average, the rms, or the peak rating of components. The equipment must be derated as necessary for the environment and the application of the components.
  
• Safety Grounding of Capacitive Components: Use automatic-discharge devices on equipment with stored energy of 100J or more. Suitable and visible manual-grounding devices must also be provided to short-to-ground all dangerous equipment while work is being performed.
  
• Electrical Equipment Rooms: Place an identifying label or sign on the door when equipment that may require servicing, manipulation, or inspection is concealed in an equipment closet or otherwise is obscured behind doors or panels.
  
• Reuse of Circuit Breakers: Do not purchase used or reconditioned circuit breakers from vendors outside LBNL. Reuse of LBNL circuit breakers is permitted only after the circuit breaker has been tested by the Electric Shop.

E3. Enclosures

The following specifications apply to circuits operating at greater than 50V, or storing more than 100J. An enclosure may be a room, a barricaded area, or an equipment cabinet:

• Access: Interlock easily opened doors, hinged panels, etc., that allow ready access to exposed energized components so that the act of opening de-energizes the circuit. Automatic discharge of stored-energy devices must be provided.  See Appendix I, Large Capacitor Hazards, in this chapter.
  
• Doors: Doors should be key-locked, and the same key should also be used for the locks in the control-circuit interlock chain, if applicable. This key must not be able to be removed from the door unless the door is closed and locked.
  
• Heat: Mount heat-generating components, such as resistors, so that heat is safely dissipated and does not affect adjacent components.
  
• Isolation: Ensure that the enclosure physically prevents contact with live circuits. The enclosure can be constructed of conductive or nonconductive material. If conductive, the material must be electrically bonded and connected to a good electrical ground. These connections must be adequate to carry all potential fault currents.
  
• Seismic Safety: Secure all racks, cabinets, chassis, and auxiliary equipment against movement during earthquakes. (See PUB 3000, Chapter 23, Seismic Safety.)
  
• Strength: Ensure that enclosures are strong enough to contain flying debris caused by component failure.
  
• Ventilation: Ensure that ventilation is adequate to prevent overheated equipment, and to purge toxic fumes produced by an equipment fault. Ventilation openings must not be obstructed.
  
• Visibility: Ensure that enclosures large enough to be occupied by personnel allow exterior observation of equipment and personnel working inside the enclosure.
  
• Warning Indicators: When systems other than conventional facilities represent Class 4A, 4B, or 3B hazards (see Hazard Class Charts in Sections 8.7.3.1 and 8.7.3.2), provide those systems with at least one of these safety measures:
  
• A conspicuous visual indicator that is clearly visible from any point where a person might make hazardous contact or entry.
  
• A clearly visible primary circuit breaker or “off” control button on the front of the enclosure.
  
• Be aware, however, that industrial systems may vary from these standards.