Identifying Grounding Connectors and Bushings

In Article " Identifying Correct Grounding Tools and Equipment ", I explained the following points: 

  • Exothermic Weld Splice,
  • Compression Tools and Dies.

Today, I will explain how to identify Grounding Connectors and Bushings as follows.

You can review the following Articles For more information:

8- Identifying Grounding Connectors and Bushings

As an Electrical Inspector, you must know that the grounding connections are usually made by one of the two following methods:

  1. Soldered Splice,
  2. Solderless Splice (Compression Connectors).

8.1 Soldered Splice

  • Soldered splices are seldom used by Many Authorities, and then only on a recommendation from the equipment manufacturer.  Installation and inspection of a soldered splice must be made according to the manufacturers’ recommendations.

8.2 Solderless Splice (Compression Connectors)

  • Solderless splices, also called compression connectors, are most often used many installations.  These types of splices use some type of mechanical pressure to hold the conductors together.
  • While compression connectors can join wires of any size, most electrical contractor usually uses them for 10 mm2 (No. 8 AWG) conductors and larger.  They are used for service connections and in industrial distribution systems.  All compression connectors must be tinned copper.  The connectors will have a wire size identification stamped on the connector, or a manufacturers’ catalog number will be stamped on the connector to aid the Inspector in determining that the correct size connector is being used.

Types of Solderless Splice (Compression Connectors)

The following types of compression connectors are commonly used:

  1. Wire nut
  2. Split bolt
  3. Butt-splice
  4. C-tap
  5. Crimp-type
  6. Terminal Lugs

Note: Screw-type connectors are also available, but most of local regulations prohibit their use.

A- Wire Nut Connectors

Wire nuts (see figure.1) are used only for indoor lighting and receptacle circuits in non-industrial applications.  They are used on electrical wires smaller than No. 6 (AWG). Wire nuts are color-coded. Each wire nut should have a catalog number on it. The inspector can check the catalog to determine that the correct size is being used.

Figure 1. Wire Nut Connectors

B- Split Bolt Connectors

  • Split bolts usually connect two or more 10 mm2 (No. 8 AWG) or larger conductors.  They are used for service connections and in industrial distribution systems.  
  • Figure 2A shows a split bolt being used to connect two conductors.  
  • Figure 2B shows a split bolt connecting one conductor to a continuous conductor.  This is called a tap connection.  
  • Split bolt connections must be insulated with plastic tape.  Split bolts are marked with a wire size number or a catalog number.  The Inspector can check the manufacturer’s catalog to verify that the correct size split bolt is being used.


Figure 2. Split bolt connections

C- Butt-splice

  • Butt-splice connectors are used to connect two conductors.  
  • Figures 3A and 3B show typical butt-splice installations.  
  • A crimping tool is used to apply the mechanical pressure needed to make the proper connection.  Butt-splice connections must be insulated with plastic tape.

Figure 3.  Butt-splice connectors

C-tap Connectors

  • C-tap connectors (Figures 4A and 4B) are used to connect a single wire into a continuous run of the same or larger wire. 
  • These connections must be insulated with tape or some other method after installation is completed.  
  • A crimping tool is used to compress the C-tap connection.

Figure 4.  C-tap connectors

D- Crimp-type Connectors

  • Crimp-Type connectors are applied using mechanical pressure from a crimping tool.  
  • Figure 5A shows a crimp-type connector.  
  • Figure 5B shows a crimp-type connector after installation and insulation.
  • Crimp-type connectors are used to join wires from size 1.5 mm2 (No. 16 AWG) to 4 mm2 (No. 12 AWG). 
  • These connections must be insulated after installation.


Figure 5.  Crimp type connector (A); crimp type connector installed (B)

  • The lug terminals (see figure.6) are crimp connectors  for power cable conductors. These connectors are used  when splicing and terminating power cable.
  • The lug terminal comes in an extremely wide variety of shapes and sizes. They may be bare or insulated. Methods of connecting to the cable vary as follows:

  1. Ferrules, which are used on flexible cables to prevent the strands from spreading out and are then connected using a screw or clamp terminal.
  2. Large power cables where the lug is compressed onto the cable using a hydraulic type crimptool. The lug is then connected to a post or screwhead terminal.

Figure 6. Terminal Lugs

In the next article, I will explain Some Work Aids for Inspection of ground Grids, Rods, and Fence grounds. Please, keep following

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