Electrical

Where to Ground the Service

The incoming neutral conductor of a utility company’s service entrance is grounded at the pole or pad-mount transformer. Once at the residence, this neutral is once again bonded to ground at the first means of over-current protection in the main disconnect.

The neutral (white) should not touch the ground (bare or green) anywhere in the house except here at the main disconnect. This is a safety feature that provides a separate path to ground from the neutral conductor. The ground wires of the individual branch circuits are all connected into the same grounding bar in the main panel. The ground wires carry the ground to each and every device, fixture, and appliance in the house.

Grounding Electrodes

The point at which the ground for the residence is derived is the grounding electrode. This is usually the incoming water line (if metal pipe), and a pair of driven 8-ft. ground rods spaced at least 6 ft. apart. Some jurisdictions require both.

The ground wire that is run from the grounding electrode to the main breaker is called the grounding electrode conductor. For grounding to a made electrode, such as a grounding rod, the code allows the use of 6-gauge copper as the conductor. For runs of 20 ft. or longer, 4-gauge copper is recommended. The conductor must be full sized, however, when used as a ground connection to water pipes or as a jumper around water meters or water heaters (below).

Figure: Grounding Electrode Conductor Sizes
1) The grounding electrode conductor is the wire that connects the grounding electrode (usually a pair of driven rods or an incoming metal water service) to the service neutral wire at the main service disconnect.2) Grounding conductors smaller than #6 must be run in conduit or armored cable.For grounding a service panel to a “made electrode” such as a grounding rod, 6-gauge copper is typically adequate. For runs of over 20 ft. from service panel to grounding rods, increase to 4-gauge wire. The conductor must be full size, however, when used as a ground connection from water pipes or as jumpers around water meters and water heaters.
1) The grounding electrode conductor is the wire that connects the grounding electrode (usually a pair of driven rods or an incoming metal water service) to the service neutral wire at the main service disconnect.
2) Grounding conductors smaller than #6 must be run in conduit or armored cable.

For grounding a service panel to a “made electrode” such as a grounding rod, 6-gauge copper is typically adequate. For runs of over 20 ft. from service panel to grounding rods, increase to 4-gauge wire. The conductor must be full size, however, when used as a ground connection from water pipes or as jumpers around water meters and water heaters.

The grounding electrode conductor must be continuous from one end to the other, even when connected to multiple ground rods. Outside the house, it can be stapled along the outside of the house without conduit if it is 6-gauge or larger, but it should be run in conduit if subject to physical damage. If not attached to the house, the conductor should be buried at least 6 in. and bonded to the ground rods with an approved clamp.

Bonding the Water System

Even if the water system for a house enters in plastic pipe and is not used for the grounding electrode, the copper piping of the water system must be bonded to the electrical system ground. This ensures that no stray voltage enters any metal plumbing components or fixtures.

When attaching a bonding wire or electrode conductor to a water pipe, use grounding clamps designed for water pipe attachment. If a water meter is present, two clamps must be used, one on either side of the water meter, with a bonding jumper (ground wire) in between (below).

Figure: System Grounding
For grounding a service panel to a “made electrode,” such as a grounding rod, 6-gauge copper is typically adequate. For runs of over 20 ft. from service panel to grounding rods, increase to 4-gauge wire. The conductor must be full size, however, when used as a ground connection from water pipes or as jumpers around water meters and water heaters.
For grounding a service panel to a “made electrode,” such as a grounding rod, 6-gauge copper is typically adequate. For runs of over 20 ft. from service panel to grounding rods, increase to 4-gauge wire. The conductor must be full size, however, when used as a ground connection from water pipes or as jumpers around water meters and water heaters.

Bonding Service Equipment

All enclosures of the electrical service must be bonded to the service grounding system, including any meter sockets or metal junction boxes (see Figure: System Grounding, above). All metal boxes in the building’s branch circuitry must be bonded. Non-metallic boxes are not required to be bonded, but the branch circuit’s ground wire must extend to any fixture or device that is installed in a non-metallic box.

By code, all aboveground gas pipes must also be grounded to service equipment, using a clamp listed for connection to steel pipe and copper and aluminum wire. This rule is sometimes considered controversial, and many inspectors will not enforce it, believing that it can create a hazard if a ground-fault occurs and heat builds up before a breaker trips. However, there is no evidence this will result. On the contrary, bonding the gas pipe to the service equipment provides a very good ground, increasing the likelihood that a circuit breaker will trip if a ground-fault occurs.