Copper pipes are grounded primarily for electrical safety and to reduce corrosion caused by galvanic action. This essential practice prevents electric shock hazards and extends the lifespan of the plumbing system.
The Dual Purpose of Grounding Copper Pipes
Grounding metal plumbing, including copper pipes, is a critical safety and maintenance measure. It serves a dual purpose: safeguarding against electrical hazards and mitigating specific types of corrosion.
Ensuring Electrical Safety
In an electrical system, grounding provides a safe path for electricity in case of a fault. For copper pipes, this means:
- Preventing Electric Shock: Should an electrical wire accidentally come into contact with the pipe (e.g., through a faulty appliance or wiring), the ground connection provides a low-resistance path for the current to flow back to the electrical panel. This rapidly trips the circuit breaker or blows the fuse, cutting off power and preventing the pipe from becoming energized and a shock hazard.
- Equipotential Bonding: Grounding ensures that all conductive objects in a building—including pipes, electrical enclosures, and structural steel—are at the same electrical potential. This prevents dangerous voltage differences from occurring between them, which could lead to a shock if a person touches two different objects simultaneously. Learn more about bonding and grounding from the National Electrical Code (NEC).
- Mitigating Lightning Strikes: While not the primary purpose, a properly grounded plumbing system can offer an additional path for lightning current to dissipate safely into the earth, reducing damage to the building and its occupants.
Preventing Galvanic Corrosion
Beyond electrical safety, grounding (often through bonding) plays a crucial role in preventing a specific type of metal degradation:
- Reducing Galvanic Action: Copper pipes, like all metals, can corrode. One significant cause is galvanic corrosion, which occurs when two dissimilar metals are in electrical contact within a conductive fluid (an electrolyte, like water in pipes). This creates a weak electrical current, similar to a battery, causing the more "active" metal to corrode faster than it normally would.
- Grounding is a key component in reducing corrosion caused by galvanic action. By bonding the copper pipes to other conductive objects and the main electrical ground, we effectively eliminate the difference in potential (voltages) between them.
- Voltages can form where there is a resistance, so bonding eliminates these differences in potential between the copper pipe and other conductive objects (e.g., a steel water heater, a different metal pipe, or even the rebar in a concrete slab). This stops the flow of current that drives galvanic corrosion, protecting the pipes.
- Minimizing Stray Current Corrosion: In some instances, unintended electrical currents (stray currents) can flow through metallic pipes. Where these currents exit the pipe to return to their source, they can accelerate corrosion. Proper grounding helps to direct these currents safely back to the electrical ground, rather than allowing them to use the pipes as an uncontrolled pathway.
How Copper Pipes Are Grounded
The grounding of copper pipes is typically achieved by:
- Bonding to the Electrical Service: Copper water piping systems are required to be bonded to the building's main electrical service grounding electrode system. This is usually done with a bare or insulated copper conductor connected from the cold water pipe (typically within 5 feet of its entry into the building) to the main electrical panel's ground bus.
- Jumpering Around Equipment: When non-conductive components, such as plastic water filters, water meters, or dielectric unions, are installed in a metallic piping system, a bonding jumper must be installed around them to maintain electrical continuity throughout the entire metal piping system.
- Connecting All Metal Components: All sections of metal water piping, including hot and cold lines, must be electrically continuous and bonded to the main electrical ground.
Benefits at a Glance
| Benefit Area | Description |
|---|---|
| Electrical Safety | Provides a safe path for fault currents, preventing electrocution hazards. Ensures equipotential bonding, minimizing voltage differences between conductive objects. Helps dissipate lightning energy. |
| Corrosion Control | Reduces galvanic corrosion by eliminating electrical potential differences between copper pipes and other conductive materials, preventing the formation of corrosive electrochemical cells. Mitigates the effects of stray electrical currents on pipe integrity. |
Regulatory Requirements
Grounding and bonding requirements for plumbing systems are mandated by electrical codes in many regions, such as the National Electrical Code (NEC) in the United States. Adhering to these codes is crucial for the safety and longevity of building systems.
