Rewireable (Ceramic) Fuses
What this is
Rewireable (ceramic) fuses were commonly installed in Australian homes for many decades and are still found in service today, particularly in older properties.
They use a replaceable fuse wire that melts when too much current flows, disconnecting power to the circuit and protecting the fixed wiring.
When they stopped being installed
Rewireable fuses were phased out of new electrical installations in the early 1990s.
Since 1991, they have not been permitted to be installed in new electrical work.
As a result, where rewireable fuses are found today, they form part of an existing installation, rather than recent electrical work.
Their presence generally reflects the age of the electrical system, not automatically its safety or condition.
Why they’re still found in homes
In many properties, rewireable fuses have remained in service because:
The electrical system has continued to operate
No major renovations have required upgrades
The switchboard has not been altered
Their presence alone does not automatically mean the installation is unsafe.
How they compare to modern protection
Modern electrical installations are designed in line with AS/NZS 3000, which sets out current electrical safety expectations.
Requirements relating to circuit protection and fault protection are covered broadly in Section 2 of the standard.
Compared to modern circuit breakers and safety switches, rewireable fuses:
Do not provide earth leakage (RCD) protection
Rely on the correct size fuse wire being installed
Can respond more slowly to certain fault conditions
Because of this, they lack several safety features that are standard in newer switchboards.
Usual inspection status
Rewireable fuses are often classified as “Not Urgent / Plan for Later” when:
They are intact and operating correctly
There are no signs of overheating or damage
The switchboard enclosure is in reasonable condition
In these cases, they are noted as legacy protection, rather than an immediate safety concern.
Modifications and additions
While rewireable fuses may remain in service in existing installations, new electrical work is not permitted to be carried out on circuits protected by rewireable fuses.
This means:
New outlets, lights, or appliances cannot be added to these circuits
Circuit alterations require modern protection to be installed first
This requirement exists because new electrical work must meet current safety expectations, including modern fault and earth leakage protection.
This does not mean existing wiring must be replaced immediately — it simply affects how future electrical work is managed.
Using the wrong size fuse wire
Rewireable fuses rely on a specific size of fuse wire to protect the circuit correctly.
If the wrong size wire is installed, the fuse may not operate as intended.
Fuse wire that is too thick
May not melt when required, allowing excessive current to flowFuse wire that is too thin
May blow too easily, leading to nuisance faults and repeated replacementUnknown or inconsistent wire sizes
Common in older installations where fuse wire has been replaced over time
What happens if wiring isn’t properly protected
Electrical wiring is designed to safely carry only a certain amount of current.
The fuse is intended to disconnect the supply before the wiring becomes overloaded.
If protection is incorrect:
Heat can build up in the cable itself
This often occurs inside walls, ceilings, or under floors
Cable insulation can gradually degrade or become brittle
As insulation breaks down and heat continues to develop, the risk of fire increases, particularly if a fault occurs and the protection does not disconnect quickly enough.
This does not mean a fire is likely or imminent — it means the safety margin built into the system is reduced.
For this reason, incorrect fuse wire is often classified as an Immediate Safety Risk during an inspection.
When rewireable fuses may be an immediate safety risk
Rewireable fuse circuits may be classified as Immediate Safety Risk if issues such as the following are present:
Incorrect or oversized fuse wire
Signs of overheating or burning
Exposed live parts
Damaged or deteriorated fuse carriers
Unsafe access to live components
In these cases, the concern is the condition and level of protection, not simply the age of the equipment.
Future considerations
In some cases, equipment that is currently operating without issue may need to be replaced in the future if circumstances change.
This could occur if:
The equipment deteriorates over time
Signs of heat damage develop
Access to live parts becomes unsafe
Electrical work is required on the circuit
The switchboard is altered or upgraded
These situations cannot always be predicted during an inspection and may arise later.
What this does not mean
This does not mean:
Replacement is required now
The installation is unsafe by default
Action must be taken unless conditions change
Most inspections identify items that remain suitable for continued use, even if they differ from modern installations.
Typical next steps
Common approaches include:
Monitoring condition over time
Planning upgrades alongside renovations or other electrical work
Upgrading individual circuits to modern protection
Replacing the switchboard when broader work is undertaken
There is no single “right” approach — decisions are usually based on condition, future plans, and overall safety.
Important context
Electrical standards evolve over time.
Inspections consider both current safety expectations and the condition of existing installations, not just the age of equipment.
The purpose of noting rewireable fuses in an inspection is to provide clarity and information, so decisions can be made calmly — now or later.
