Okay, let's break down what you're asking about upgrading your fuse panel and adding a new circuit for a tankless water heater.

Important Considerations



Local Codes and Permits

This is the most important thing. Electrical work is heavily regulated for safety. You absolutely must check with your local building department or electrical inspector before you start any work. They will tell you what permits are required, what codes are in effect in your area (e.g., what version of the National Electrical Code (NEC) is enforced), and what inspections you'll need to pass. Doing electrical work without proper permits and inspections can lead to fines, insurance problems, and, most importantly, safety hazards.

Qualified Electrician

If you are not completely confident in your electrical skills and knowledge of the NEC, you should hire a qualified and licensed electrician to do this work. Electrical work is dangerous and can be deadly if done incorrectly.

Answering Your Specific Questions


Changing Out an Old Fuse Panel

Yes, it is possible to change out an old fuse panel with a new breaker panel. However, there are some important factors:

Adequate Ampacity

The new panel needs to have an amperage rating equal to or greater than the existing service. (e.g. existing 100 amp panel, new panel must be 100 amp or greater)

Sufficient Spaces

Make sure the new panel has enough breaker spaces to accommodate all the existing circuits plus the new circuit for your tankless water heater. It's generally a good idea to get a panel with more spaces than you think you'll need, as you may want to add circuits in the future.

Proper Grounding

The grounding system needs to be brought up to current code. This may involve installing new grounding electrodes (ground rods) and ensuring proper bonding of metal water pipes, gas pipes, and other metallic systems.

Wiring Condition

When you remove the fuse panel, inspect the existing wiring. If the wiring is old and deteriorated (cracked insulation, brittle, etc.), it might be necessary to replace it.

Arc Fault Protection (AFCI)

Modern electrical codes often require AFCI protection for many circuits in a home (especially bedroom circuits). Check your local codes.2.

Adding a New 2-Pole 30A Circuit with GFCI for Tankless Water Heater



GFCI Breaker Requirement

GFCI protection is typically required for outlets and hardwired equipment located in areas where moisture is present (bathrooms, kitchens, outdoors, etc.). Tankless water heaters installed in those areas will likely require GFCI protection. Check your local codes.

Circuit Sizing

The 30A, 2-pole breaker is appropriate for the tankless water heater IF (and this is a big if) the heater's specifications require it. You must check the manufacturer's installation instructions for the exact voltage, amperage, and breaker size requirements. A 30A breaker on too small of a load can create serious risk.

Wire Size

You'll need to use the correct wire size for a 30A circuit. Typically, this would be #10 AWG copper wire. Again, check your local codes, as they may have specific requirements.

Romex (NM Cable)

Romex (NM) cable is commonly used for residential wiring. Make sure it's rated for the amperage and voltage of the circuit.

Dedicated Circuit

The tankless water heater must be on a dedicated circuit, meaning no other outlets or appliances can share that circuit.3.

Regular Breakers for Other Circuits

Yes, you can use standard (non-GFCI) breakers for the other circuits in the panel, unless local codes require GFCI or AFCI protection for those circuits.

Safety Considerations



Turn off the Main Breaker

Before you start any work on the electrical panel, turn off the main breaker that feeds the panel. Verify that the power is off with a non-contact voltage tester.

Work in Daylight (Ideally)

It's much safer and easier to work on electrical systems in good lighting.

Wear Safety Gear

Wear appropriate safety glasses and insulated gloves.

In Summary


Check Local Codes and Permits

This is non-negotiable.2.

Consult an Electrician (Recommended)

Unless you are highly skilled and knowledgeable about electrical work, it's best to hire a qualified electrician.3.

Plan Carefully

Make sure the new panel has enough spaces and is properly grounded.4.

Size the Tankless Water Heater Circuit Correctly

Use the manufacturer's specifications for breaker size and wire gauge.5.

Follow All Safety Precautions.

I hope this is helpful. Remember that this information is for general guidance only and should not be considered a substitute for professional advice. Good luck, and stay safe! Flag for review