What is the difference between a fuse box and a breaker panel?

Fuse Box vs. Circuit Breaker Panel: What NB Homeowners Need to Know

Many older New Brunswick homes still have fuse boxes, and homeowners are often confused about whether they need to upgrade. Here's the practical difference between the two systems and when replacement makes sense.

How Fuse Boxes Work

A fuse box uses replaceable fuses to protect circuits from overcurrent. Each fuse contains a metal strip calibrated to melt at a specific current (15A, 20A, 30A). When too much current flows, the strip melts ("blows"), breaking the circuit and preventing overheating.

Types of fuses in residential panels:

• Screw-in (Edison base) fuses: The most common. They screw into a socket like a light bulb. The fuse window shows the condition — clear glass means good, darkened or broken filament means blown.


• Type S fuses: Tamper-resistant — each amperage rating has a different base size, preventing overfusing. Required by code when replacing Edison base fuses.


• Cartridge fuses: Cylindrical fuses used for 240V circuits (stove, dryer, main disconnect). They pull out of spring clips.

How Breaker Panels Work

A circuit breaker panel uses resettable switches to protect circuits. When too much current flows, a bimetallic strip or electromagnetic mechanism trips the switch to the OFF position. You reset it by pushing the handle from TRIPPED → OFF → ON.

Modern breaker panels also support:

• GFCI breakers — protect against ground faults (shock prevention)


• AFCI breakers — protect against arc faults (fire prevention)


• Dual-function breakers — combine GFCI and AFCI in one device


• Tandem breakers — fit two circuits in one slot for space efficiency

Key Differences

| Feature | Fuse Box | Breaker Panel |
|---------|----------|---------------|
| Overcurrent protection | Fuse blows (must replace) | Breaker trips (reset by hand) |
| Convenience | Must keep spare fuses on hand | Just flip the switch |
| Typical service size | 60A (sometimes 100A) | 100A, 150A, or 200A |
| GFCI/AFCI support | Not available | Built-in GFCI and AFCI breakers |
| Circuit capacity | Usually 4–12 circuits | 20–42+ circuits |
| Age | Typically 1940s–1970s | 1970s–present |
| CEC compliance | Grandfathered | Current code |

The Overfusing Problem

The biggest safety issue with fuse boxes isn't the fuse technology — it's overfusing. When a 15A fuse keeps blowing (because the circuit is overloaded), homeowners or previous owners often replace it with a 20A or 30A fuse. This defeats the overcurrent protection — the wiring (14 AWG, rated for 15A) can now carry 20A or 30A without the fuse blowing, causing the wire to overheat.

This is extremely common in older NB homes. A home inspector or electrician opening a fuse box and finding 30A fuses on 14 AWG wiring is a fire hazard that needs immediate correction.

Breaker panels prevent this because breakers are specific to the panel and you can't easily swap a 15A breaker for a 30A one — the breaker rating is fixed.

Do You Need to Upgrade?

You should upgrade if:

• Your fuse box is 60A — modern homes need 200A minimum for today's electrical loads


• You're adding major appliances (heat pump, EV charger, hot tub, electric stove)


• You find overfused circuits (wrong amperage fuses for the wire gauge)


• Your insurance company requires it — many NB insurers charge higher premiums or refuse to insure homes with fuse boxes


• You're selling the home — buyers and their inspectors will flag it


• You need GFCI or AFCI protection — only available with breaker panels

• Your fuse box is 100A (uncommon but exists)


• All fuses are correctly sized for their circuits


• You're not adding any major loads


• Your insurance company is comfortable with the current setup


• The wiring throughout the home is in good condition

Upgrade Costs in New Brunswick

| Upgrade | Cost |
|---------|------|
| 60A fuse box → 200A breaker panel | $3,000–$5,000 |
| 60A fuse box → 200A panel + service upgrade (mast, meter base) | $4,000–$6,500 |
| 100A fuse box → 200A breaker panel | $2,500–$4,000 |

The process takes 1–2 days. Power is off for 4–8 hours during the swap. NB Power coordinates the disconnect and reconnect. A TSANB inspection is required before reconnection.

What Happens During the Upgrade

Finding Spare Fuses

If you're keeping your fuse box for now, stock up on the correct amperage fuses. Type S fuses (tamper-resistant) in 15A and 20A ratings are available at Kent and Home Hardware in NB for $3–$8 per fuse. Keep at least 4 spares of each size you use. Having the right fuse on hand at 2 AM during a winter storm prevents the dangerous temptation to overfuse.

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