Overfused breaker on an inspection report: risk and cost

What does an overfused breaker mean on an inspection report?

An overfused breaker is rated for more current than the wire behind it can safely carry. The breaker is meant to trip before the wire overheats, and a breaker that is too big may not. Have a licensed electrician open the panel and give you a written bid before your inspection deadline. Then ask the seller for that number.

Key takeaways

• Air conditioner and heat pump circuits are the exception. The unit's nameplate can allow a bigger breaker, so the electrician checks the label.
• The national breaker-swap figure below excludes circuit wiring. If the circuit needs new wire, make sure the bid prices it.
• The standards of the International Association of Certified Home Inspectors (InterNACHI) don't require inspectors to look for overfusing, so the report may miss some. Have the electrician check the whole panel while it's open.

How serious is an overfused breaker?

The International Association of Certified Home Inspectors (InterNACHI) says in its electrical inspection course: if a 30-amp breaker protects wire rated for 15 amps, "we are likely to see the conductor overheating and potentially starting a fire."

The rule is simple. The breaker's rating can't be higher than the wire's. For the copper wire in most houses, InterNACHI's course gives these limits:

Aluminum wire gets a smaller breaker at each size. If your report also flags aluminum branch wiring, mention it when you book the electrician.

There is one exception. InterNACHI notes that an inspector "may find a 50-amp 'AC' breaker on a 10-gauge wire" that the unit's nameplate allows. If the flagged breaker feeds an air conditioner or heat pump, ask the electrician to compare it with the nameplate.

If your report mentions overheating, arcing or smoke damage at the panel, book the electrician first, before any money talk.

How much does it cost to fix an overfused breaker?

The fix is making the breaker and the wire match. Your electrician tells you whether that means a smaller breaker or heavier wire. On an older fuse panel, InterNACHI's course recommends type S fuses and adapters, which accept only the correct fuse size. The breaker swap is the part with published prices:

Kept prices every line of an inspection report for $79, usually under 4 hours.

A single-pole breaker serves a 120-volt circuit. A double-pole breaker serves a 240-volt circuit, like a dryer or water heater. Homewyse's figure assumes a basic job in an easy-to-reach panel.

Say your report flags one overfused breaker. At the Homewyse rate, the swap runs $319 to $382. Add a permit if your town requires one, which G4 (local, East Texas) puts at $25 to $300. That makes $344 to $682 ($319 + $25 and $382 + $300). Homewyse's figure includes a 2-hour minimum labor charge that can cover other tasks, so have every flagged breaker priced on one visit. If the circuit needs new wire, only the electrician's written bid tells you the total.

Who fixes it before my deadline?

A licensed electrician. Ask them to do three things on one visit:

• Confirm the wire size on each flagged circuit and say whether the fix is a new breaker or new wire.
• Check the other breakers in the panel. InterNACHI's inspectors aren't required to look for overfusing, so the report may not list every one.
• Put the price in writing, with any permit included.

While the panel is open, have them look at any other panel lines on your report, such as no main disconnect or a Federal Pacific panel. The electrical findings guide lists the rest. For getting a bid fast, see how to get repair estimates during the inspection period.

What do I ask the seller for?

Ask for the electrician's bid total, and attach the bid. Sample wording: "Correct overfused breaker(s) to match each circuit's wire size, licensed electrician, permit where required, $[amount from the electrician's written bid]." Ask for a credit if you'd rather hire your own electrician. Ask for the repair if you want it done before you move in.

If the seller does the work, ask for a licensed electrician, a permit where your town requires one, and the invoice before closing. The buyer repair request letter template has the wording. What to ask for after a home inspection covers the rest of your list.

What if the seller says no?

Once an electrician has priced it, an overfused breaker is a known cost. That makes it a line to negotiate, not by itself a reason to leave. It changes if the bid says several circuits need new wire and the total no longer fits your budget. Weigh that with when to walk away after a home inspection.

Your contract sets the exact deadline and terms, so confirm them with your agent.

Is an overfused breaker the same as an overloaded circuit?

No. On an overloaded circuit, too much current is drawn, and a correctly sized breaker trips to protect the wire. InterNACHI's course says the breaker "will automatically open the circuit and protect the conductors if the current is too high." An overfused breaker is too big to trip at the wire's limit, so the wire can overheat first. As the course puts it, when the breaker is rated above the wire, "something other than the breaker is likely to overheat and fail."

A breaker that keeps tripping needs an electrician to find the cause, not a bigger breaker. On old fuse panels, InterNACHI warns that a too-large fuse ends up "effectively turning the conductor into the fuse."

Is an overfused breaker a code violation?

The model residential code caps each breaker at the rating its small conductor table lists for that wire. Which version applies to your house depends on the code your city or county adopted. Your local building department or a licensed electrician answers that for your address.

How do I know what the rest of my list is worth?

If the breaker is one line of many, upload your inspection report to Kept and spend your remaining days on the bids that need an electrician.

Sources

• InterNACHI, How to Perform Residential Electrical Inspections course
• InterNACHI, Inspecting Oversized "AC" Breakers on Small-Gauge Wires
• UpCodes, Residential Code Section E3705.5.3, Small Conductors
• Homewyse, Cost to Install Circuit Breaker
• G4 Electrical, Plumbing and Air, How Much Does It Cost to Replace a Circuit Breaker