- Visual and Mechanical Inspection
- Electrical Tests
- Test Values
- TABLE 100.12 – US Standard Fasteners – Bolt-Torque Values for Electrical Connections
Cables, Low-Voltage, 600 Volt Maximum
- Compare cable data with drawings and specifications.
- Inspect exposed sections of cables for physical damage and correct connection in accordance with single-line diagram.
- Inspect bolted electrical connections for high resistance using one of the following methods:
- Use of low-resistance ohmmeter in accordance with previous Section 1.2.
- Verify tightness of accessible bolted electrical connections by calibrated torque-wrench method in accordance with manufacturer’s published data or Table 100.12.
- Perform thermographic survey:
- Perform thermographic survey when load is applied to the system
- Remove all necessary covers prior to thermographic inspection. Use appropriate caution, safety devices, and personal protective equipment
- Perform a follow-up thermographic survey within 12 months of final acceptance by the owner
- Perform resistance measurements through bolted connections with low-resistance ohmmeter.
- Perform insulation-resistance test on each conductor with respect to ground and adjacent conductors. Applied potential shall be 500 volts DC for 300 volt rated cable and 1000 volts DC for 600 volt rated cable. Test duration shall be one minute.
- Perform continuity tests to insure correct cable connection.
- Verify uniform resistance of parallel conductors.
- Compare bolted connection resistances to values of similar connections.
- Bolt-torque levels should be in accordance with Table 100.12 unless otherwise specified by the manufacturer.
- Microhm or millivolt drop values shall not exceed the high levels of the normal range as indicated in the manufacturer’s published data. If manufacturer’s datais not available, investigate any values which deviate from similar connections by more than 50 percent of the lowest value.
- Insulation-resistance values should not be less than 50 megohms.
- Investigate deviations in resistance between parallel conductors.
US Standard Fasteners – Bolt-Torque Values for Electrical Connections
a. Consult manufacturer for equipment supplied with metric fasteners.
b. This table is based on bronze alloy bolts having a minimum tensile strength of 70,000 pounds per square inch.
c. This table is based on aluminum alloy bolts having a minimum tensile strength of 55,000 pounds per square inch.
d. This table is to be used for the following hardware types:
- Bolts, cap screws, nuts, flat washers, locknuts (18–8 alloy)
- Belleville washers (302 alloy).
Resource: Acceptance Testing Specifications for Electrical Power Distribution Equipment and Systems – NETA 2003