Okay, let's break down the grounding/bonding requirements in this scenario. You're right to be meticulous; incorrect grounding can be dangerous.

Summary

You probably need to bond the lead water pipe, but it's unlikely you need to use it as a grounding electrode. Given the situation, focusing on proper bonding to the grounding electrode system (rods) and considering supplemental grounding is the best approach.

Here's a detailed explanation


Water Pipe as a Grounding Electrode (NEC 250.52(A)(1)) The NEC permits the use of a metal water pipe in direct contact with the earth for 10 feet or more (including any metal well casing bonded to the piping) as a grounding electrode. However, it is not mandatory to use the water pipe as a grounding electrode unless it meets the 10-foot burial requirement.2. The PEX Factor

PEX is non-conductive. Any length of PEX in the water piping system breaks the electrical continuity required for the water pipe to act as a continuous grounding electrode. The very short section of lead pipe disqualifies the water pipe as a sole electrode.3.

Grounding Electrode System (NEC 250.50)

NEC requires you to create a grounding electrode system. This system should be bonded together. Grounding Electrode Conductors (GECs) must connect to: Any existing metallic water pipes that meet the 10' in-ground requirement Ground rods/pipes. Concrete-encased electrodes (if any) Ground rings (if any) Since the water pipe does not meet the criteria, your grounding rods become your Grounding Electrode System.4.

Bonding the Water Pipe (NEC 250.104(A))

This is the crucial part. The bonding of interior metal water piping systems is REQUIRED. Why bond it? Bonding is to ensure that the metallic water piping, should it become energized due to a fault, will have a low-impedance path back to the service, causing the breaker to trip and clear the fault. Without bonding, the pipe could become energized and present a shock hazard.

Method of Bonding

You must bond any metal water piping likely to become energized to: The service equipment enclosure; The grounded conductor at the service; The grounding electrode conductor (GEC), if of sufficient size; One or more grounding electrodes used.5.

Sizing the Bonding Jumper (NEC 250.104(A))

The bonding jumper size is based on the size of the service entrance conductors. Consult NEC Table 250.102(C)(1) for the appropriate size. Usually, it will be smaller than the GEC.

Specific Recommendations for Your Situation


Grounding Electrode System

Since the water pipe doesn't qualify, your primary grounding electrode system will be the ground rods and GEC. Make sure to follow proper installation methods for ground rods (spacing, depth, etc.) as per NEC.2.

Bonding the Lead Water Pipe

Run a bonding jumper from the lead water pipe to either: The service equipment enclosure; The neutral bus in the service panel; The grounding electrode conductor (GEC), if it's sized appropriately; A grounding electrode used.3.

Location of Bonding Jumper

The bonding jumper should be connected to the lead water pipe within 5 feet of where the water pipe enters the building. This minimizes the length of unbonded pipe that could become energized.4.

Concerning Distance (50 Feet)

50 feet is a long run for a bonding jumper to travel from the ground rods to the water pipe. This can increase impedance. Consider these alternatives:

Run a separate bonding jumper from the lead pipe back to the service panel. This is likely the best approach. Use a bonding jumper sized according to Table 250.102(C)(1) based on the size of your service conductors. Install a supplemental grounding electrode closer to the water pipe. This is a good general practice. For example, you could drive another ground rod near the point where the water pipe enters the building and bond the pipe to that rod. This helps provide a more localized, low-impedance path to ground.

Important Considerations



Inspection

Always consult with your local electrical inspector. They have the final authority and may have specific requirements for your area.

Proper Connections

Use approved connectors for bonding and grounding. Make sure all connections are tight and corrosion-resistant.

Plastic Fittings

Be aware of any plastic fittings or unions in the water piping system near the point where you plan to bond. These fittings can interrupt electrical continuity and require you to bond on both sides of the fitting.

In summary, focus on establishing a solid grounding electrode system with your ground rods and GEC. Then, bond* the lead water pipe back to the service panel or to a nearby supplemental grounding electrode. This will ensure electrical safety and compliance with the NEC. Flag for review