This is a tricky situation with a few angles to consider. Here's a breakdown of my thought process and recommendation

Understanding the Issues:
Code Violation

Using a lug or terminal not rated for the conductor size is a violation of the National Electrical Code (NEC). The terminal is designed for specific conductor sizes to ensure a secure and reliable connection. Using a smaller conductor in a terminal designed for larger sizes can result in a loose connection, leading to arcing, heat, and potential fire hazards.

Grounding Integrity

The grounding conductor is a critical safety component. It provides a low-impedance path for fault current to return to the source, tripping a breaker or blowing a fuse and clearing the fault. A compromised grounding conductor reduces the effectiveness of this safety mechanism.

Old Wiring

The age of the wiring in the house adds complexity. Cloth-covered wiring can degrade over time, and the insulation can become brittle. Disturbing it further might create more problems.

Arguments for Splicing



Correcting the Violation

Splicing with #14 AWG will make the connection compliant with the terminal's rating.

Improved Grounding

Assuming the splice is done correctly, it creates a more robust grounding path.

Increased safety A proper ground is crucial for safety.

Arguments Against Splicing



Disturbing Old Wiring

Handling the old wiring could cause further degradation or insulation damage.

Potential for New Problems

If not done meticulously, a splice can introduce its own problems, such as a loose connection.

"Good Enough" Argument (but risky)

The existing #16 connection may be working and providing some grounding path. Leaving it undisturbed might seem safer than potentially creating a worse situation.

However, this is generally a bad idea from a safety perspective.Recommendation: Splice, but with Caution and Best Practices

Given the factors, my recommendation is to carefully splice #14 bare copper to the #16 grounding conductors to ensure proper grounding, using the following guidelines:1. De-energize the Circuit

Absolutely make sure the circuit is off at the breaker before doing any work. Use a non-contact voltage tester to verify.2.

Inspect the Existing Wiring

Before you do anything, carefully examine the cloth-covered wiring. Look for: Brittle or cracked insulation Exposed conductors Signs of overheating (discoloration, melting) If the wiring is in very poor condition, consider advising the homeowner to replace the wiring entirely.3.

Choose the Right Splicing Method

Use a method that is appropriate and NEC compliant, and listed for splicing different sized grounding conductors. Approved methods include:

Wire Connectors (e.g., Wirenuts, Push-in Connectors)

Use wire connectors rated for the wire gauges you're connecting (both #14 and #16). Ensure they are also rated for grounding connections. Make sure to use the correct size for the number of conductors you are connecting.

Crimped Splices

Using a crimping tool and connectors rated for the wire sizes.

Split Bolt Connectors (for larger conductors, less common in this scenario).4. Make a Secure Connection

Strip the wires carefully to avoid nicking or damaging the conductors. If using wire connectors, twist them on firmly, following the manufacturer's instructions. If crimping, use the correct crimping tool and ensure a solid crimp.5.

Protect the Splice

Wrap the splice with electrical tape to insulate it and provide mechanical protection. If the splice is in a potentially damp location, consider using a waterproof splice kit.6.

Secure the Wires

Make sure the spliced wires are neatly arranged and secured inside the electrical box to prevent stress on the connections.7.

Test

After completing the splice, use a multimeter to verify continuity between the grounding conductor and the grounding bar.

Important Considerations



Inform the Homeowner

Explain the issue and your recommendation to the homeowner. Get their consent before proceeding.

Documentation

Document the work you performed, including photos and a description of the issue and the solution. This is especially important in older homes where future electricians may need to understand the wiring configuration.

Consider a Full Electrical Inspection

Given the age of the wiring, recommend to the homeowner that they have a comprehensive electrical inspection to identify other potential issues.

Alternatives (Less Desirable)



Replacing the Ground Bar

If the existing ground bar is easily replaceable, you could replace it with one that accepts #16 AWG conductors. However, this might not be practical or cost-effective.

Adding a Supplemental Grounding Electrode

In some cases, you might be able to improve grounding by installing a supplemental grounding electrode (ground rod). However, this doesn't address the immediate issue of the undersized connection at the ground bar.

Disclaimer:

I am an AI Chatbot and not a qualified electrician. This information is for general guidance only and should not be considered professional advice. Always consult with a licensed electrician for any electrical work. They can assess the specific situation and ensure the work is done safely and in compliance with local electrical codes. Improper electrical work can be dangerous and could result in serious injury, death, or property damage. Flag for review