Is a fuse box the same as a consumer unit?

In everyday speech, yes — people use both terms for the box where the electricity supply is distributed around the property. Technically, a fuse box means an older unit using rewireable or cartridge fuses, while a consumer unit is the modern equivalent using MCBs or RCBOs with RCD protection.

Is it illegal to still have a fuse box?

No. An old fuse box is not illegal and you cannot be forced to replace one in your own home. It will, however, be flagged on an EICR — usually as a C3 improvement recommendation, or as a C2 if there is no RCD protection on circuits that require it.

How long does it take to replace a fuse box?

Around four to six hours for a straightforward domestic swap, including testing and certification. Longer if main protective bonding to gas and water needs upgrading or if existing circuits fail insulation resistance testing.

Will a new consumer unit stop my breakers tripping?

Not on its own. A breaker trips because there is a fault or an overload on the circuit. A new board with individual RCBOs will isolate the problem to one circuit and make it far easier to diagnose, but the underlying fault still needs finding and fixing.

Consumer Units

Fuse board vs consumer unit: what's the difference?

By Steve Green · Updated 6 August 2026 · 5 min read

They are the same piece of equipment at different generations. A "fuse board" or "fuse box" is an older unit using rewireable or cartridge fuses, typically with no RCD protection. A "consumer unit" is the modern equivalent — a steel enclosure fitted with MCBs or RCBOs providing both overcurrent and residual current protection to BS 7671. If yours has fuse wire in it, it is a fuse box and it predates current safety standards by decades.

Side by side

	Old fuse board	Modern consumer unit
Protective device	Rewireable or cartridge fuse	MCB or RCBO
Shock protection (RCD)	None	Yes, on all required circuits
Enclosure	Plastic, wood or bakelite	Steel (non-combustible)
Reset after a fault	Replace fuse wire by hand	Flip the switch
Fault discrimination	Poor	Circuit-by-circuit with RCBOs
Surge protection	No	Optional Type 2 SPD
Typical era	Pre-1990s	2016 onward for current spec

How to tell which you have in 30 seconds

Fuse wire or pull-out fuse carriers — old fuse board, no RCD.
Plastic enclosure with black rocker switches and a 'Test' button — a 1990s–2015 consumer unit. Functional, but not current spec.
Steel enclosure, one switch per circuit each with its own test button — a modern all-RCBO consumer unit.

Do not open the cover to check. Everything you need to identify it is visible from the outside, and what is behind the cover is live even with the main switch off.

What an old fuse board actually means for safety

Fuses protect the cable from overload and short circuit. They do not protect a person from electric shock. RCD protection — which detects current leaking to earth and disconnects in under 40 milliseconds — is what does that, and it is the single biggest safety difference between the two. It is also why an old board is nearly always raised on an EICR.

When replacement is genuinely necessary

Rewireable fuses with no RCD protection anywhere in the installation
Signs of heat damage, scorching or a burning smell at the board
A C1 or C2 coded observation on your EICR relating to the board
Adding a circuit the existing board cannot accommodate — an EV charger, shower or outbuilding
The board is in a fire escape route with a combustible enclosure

What replacement involves

A competent contractor tests every existing circuit before energising a new board, because a new RCBO will trip immediately on cabling with poor insulation resistance. That test is not optional and it is why a proper quote includes it. Sizing matters too — see what size consumer unit you need before agreeing a specification.

If testing shows the cabling itself has deteriorated, a new board is treating the symptom. Our EICR vs rewire vs consumer unit upgrade comparison explains how to decide, and fuse board replacement covers our fixed pricing.

Frequently asked

Is a fuse box the same as a consumer unit?: In everyday speech, yes — people use both terms for the box where the electricity supply is distributed around the property. Technically, a fuse box means an older unit using rewireable or cartridge fuses, while a consumer unit is the modern equivalent using MCBs or RCBOs with RCD protection.
Is it illegal to still have a fuse box?: No. An old fuse box is not illegal and you cannot be forced to replace one in your own home. It will, however, be flagged on an EICR — usually as a C3 improvement recommendation, or as a C2 if there is no RCD protection on circuits that require it.
How long does it take to replace a fuse box?: Around four to six hours for a straightforward domestic swap, including testing and certification. Longer if main protective bonding to gas and water needs upgrading or if existing circuits fail insulation resistance testing.
Will a new consumer unit stop my breakers tripping?: Not on its own. A breaker trips because there is a fault or an overload on the circuit. A new board with individual RCBOs will isolate the problem to one circuit and make it far easier to diagnose, but the underlying fault still needs finding and fixing.

Need a straight answer about your own property?

Call 0203 576 6961 — answered by a real person, available 24/7 — or request a free written quote.