How To Replace Blown Wylex Standard rewirable fuse and Retrofit 1970s Bakelite Fuse Board with Modern MCBs

I didn’t set out to become an expert in rewirable fuse boxes. I just wanted a cup of tea. The kettle wouldn’t boil, the microwave clock was off, and the office lights were dead. At first, I thought nothing of it. The dishwasher had just finished and I assumed I’d overloaded something or nudged a switch.

It wasn’t until I clocked the silent kettle and the lack of power in the office that I realised the entire ground floor was out. No post from the street group, no lights flickering next door, just me, standing in the kitchen with a broken brew and a fuse box that hadn’t been updated since the 1970s.

Living in a Victorian house often means embracing the quirks of yesteryear; high ceilings, wonky floors, and, in my case, a 1970s Wylex fuse box still clinging to the wall like a relic from a time when avocado bathrooms were all the rage. And today, during what I initially thought was a full-blown power cut, I discovered something a little more… enlightening.

FAQ – The Bloody Obvious Electrical Questions You Should Ask Before Rewiring Your Victorian Fusebox

Spoiler: it was just me. The street carried on as normal while I stood in the hallway flicking switches like a confused DJ. Over the course of two hours – that’s how long it took me to take photos of my progress and ask my trusty agent “What’s the chances of frying my arm off with this silicone spray?” accidentally, and inadvertently, I created my own FAQ.

Well, I started with the bleeding obvious: I don’t wanna fry n die. Best ask my mate. Can I remove the fuses when the breaker is NOT OFF?

Can I keep a breaker ON and pull out a fuse? Short answer: No, not safely with Wylex fuse Board.

To clarify, when the breaker is set to ‘on’ position, don’t yank out your fuse case. With your older Wylex rewirable fuse board, each fuse holder is live when the main switch is on. That means if you try to pull out a fuse while the power is on, you’re potentially exposing yourself to 230 volts of “surprise-you’re-dead” mains electricity.

Here’s the safest way to check each fuse:

1. Switch off the main switch first. That’s the white one on the far right with the red “ON” label. Flip that to OFF — this isolates all power to the circuits and makes it safe to remove and inspect the fuses.
2. Pull out each fuse one at a time. Check the fuse wire inside if it’s a rewirable one — if the wire is broken or looks burnt, that’s the culprit. Yours seem to be cartridge-type fuses, so check for obvious heat damage, burn marks, or melted plastic on the fuse holder.
3. Double-check your labelling. Since you’ve got one marked “?”, this is a good time to figure out what it controls — maybe plug in a lamp and flick that switch back on while the others are out. A bit of detective work now could save you future headaches.
4. Don’t poke or prod inside the fuse box. Even with the main switch off, internal parts can hold a residual charge, and vintage gear doesn’t have modern insulation standards.
5. Turn the main switch back on once everything’s back in place. If you get repeated tripping again after doing this, it’s time to call a sparkie.

Diagnosing a Blown Lighting Circuit in a 1970s Consumer Unit – Wylex Standard rewirable fuse

After switching the main fuseboard OFF (safety first, always), I removed each fuse carrier to inspect them. And sure enough, the one marked “Lights” had blown. It was stamped 5 AMP, with a reassuringly retro white dot — a colour code used back in the day to help identify fuse ratings at a glance. In this case, 5 amps = lighting circuit.

Now here’s where it got interesting. Inside the carrier? Two lengths of fuse wire twisted together. A textbook example of DIY enthusiasm trumping safety. Doubling up fuse wire increases its current-carrying capacity, meaning it might not break when it should — effectively bypassing the entire safety system. It’s a bit like fitting your brakes with elastic bands and hoping for the best.

So I removed the dodgy wire, replaced it with a single strand of proper 5A fuse wire, and popped the fuse back in. The lights came on without fuss. No drama. Just a little knowledge and a healthy respect for old electrics.

 

Should I Use Silicone Water Displacer Spray to Clean My Fuse Box?

Before you grab that can of WD40 spray lurking in your toolbox, hold fire until you check what’s actually in it. Not all sprays are safe for electrical components, especially when dealing with vintage fuse boxes made from Bakelite and older plastics.

The answer with a WARNING is NO – If your spray isn’t explicitly marked as an electrical contact cleaner, it’s best kept far away from anything that’s ever had 230 volts humming through it.

Safe: Sprays labelled for electronics or electrical contact cleaning. These are fast-drying, non-conductive, and designed for terminals, brass, and oxidised contact points.

Unsafe: General-purpose degreasers, silicone sprays, standard WD-40, or anything that’s flammable or slow to dry. These leave behind residues, attract dust, and if they seep into live areas, they pose a fire risk or worse.

If in doubt? Don’t spray. The fuse box isn’t a car engine. There are safer ways to clean up terminals without risking damage, and they start with your next best tool…

The Humble Toothbrush: Your DIY Secret Weapon for Safe Dry Cleaning

You know it’s the bleeding obvious that clean contacts conduct better, run cooler, and reduce the risk of intermittent faults or overheating. Give everything a careful double check, we don’t want to be fried like a battered sausage. Blow on it a bit, or used compressed air which is moisture free. If you do breathe on it, let it air out for 10 or 15 minutes before plopping back in and restoring the power. We don’t want you turning the breaker to ‘ON’ position and you end up like a frazzled fox in a black top hat and monocle to appear Victorian.

The humble toothbrush wins again. If it’s not a proper electrical contact cleaner, best to keep it well away from anything that’ll one day have 230 volts humming through it. Maybe I’m weird, but I keep at least two old toothbrushes (is the plural of toothbrush toothbri?) so I knew exactly where to find one. I love it when hoarding a random thing saves your whole day, I’ve been using a sonic toothbrush for over a year now.

 

Use a dry brush first to knock off any cobwebs, dust, or grime on the terminals, fuse clips, and carriers. If anything looks oxidised or dull, you can gently polish the brass with a bit of fine emery paper — or even a nail file in a pinch. Avoid anything that’ll crumble or leave behind fibres.

PROBLEM/SOLUTION Tiny Fiddly Threading the Fuse Wire and the Brass Screw

Once I’d cleared out the remnants of the old wire, I was finally ready to thread the new one. The ceramic fuse carrier, typical of vintage Wylex units, has a tiny central channel designed for a single strand of wire to run cleanly through. After dislodging some stubborn leftovers, it cleared out nicely — and threading the new 5A wire felt satisfyingly precise, like re-stringing a vintage violin.

Then came the screw. The non-magnetic screw, of course it’s brass, it’s electrical you fool, I said to myself.

That tiny brass terminal screw is deceptively heavy for its size, absolutely immune to magnets, because brass is non-ferrous. I balanced it on my screwdriver like a tiny circus act, holding my breath as I tried to drop it into place without it skittering off into oblivion. It did. Twice.

This is where the Blu Tack hack came in. I asked ChatGPT if it was safe to use — and it gave the green light. A tiny smudge of Blu Tack on the end of the screwdriver gave just enough grip to guide the screw into the terminal. Third time lucky, the wire was clamped tight, the screw locked down, and the fuse carrier slid neatly back into its slot with a solid click.

And just like that — I’d rewired a fuse like a 1970s electrician, but with cleaner fingernails and better lighting. The power came back on. The microwave beeped. The kettle finally boiled. All was well in the world again. Bonus cat photo.

Should I Keep the Old Fuse Box?

In short: not for long. While these Wylex units were the standard for decades, they don’t meet modern safety expectations. There’s no RCD (residual current device) to detect earth faults, and rewirable fuses rely on human judgement — not ideal in an emergency. If you’ve got one of these, it’s worth upgrading to a modern consumer unit with MCBs and RCDs. Not only is it safer, it’s also something surveyors love to see when selling a home.

Your fuse box screams 1970s to early 1980s. The black rewirable Wylex fuse board with those chunky pull-out fuse holders and the coloured indicators is classic of that era. The white twin push-button 30A breakers to the left are also typical retro additions—often installed later to protect high-load circuits like showers or cookers when someone updated part of the system without replacing the entire board.

The yellow tape labelling and mixed handwriting feels very “DIY dad with a torch in his mouth” – not uncommon back then, and in many homes still soldiering on today. Not soldering on, that’s for a different DIY article. Can you upgrade easily? Yup, as easy as pie.

Introducing miniature circuit breakers (MCBs)

For context: modern UK consumer units use miniature circuit breakers (MCBs) or RCBOs with a residual current device (RCD) built-in, and everything is clearly labelled, protected and standardised to today’s 18th Edition Wiring Regs. What you’ve got here, while nostalgic, is well overdue for a modern replacement if safety, energy efficiency, or any new electrical installs are in the pipeline.

Fusebox Glossary: Don’t Know What The Individual Parts of a Wylex Fuse Are, or the Board?

Main Isolator Switch

What it does: This is the big control lever on the right-hand side of the fuse box. When it’s ON, electricity from the street flows into your home. When you flip it OFF, you shut off the entire supply to every fuse and circuit in the board.Why it matters:
This is your main safety control. Always switch it OFF before touching anything inside the fuse box. It’s the first and most important step in any safe inspection or repair.

Fuse Carrier

Mine were Bakelite but they can also be ceramic. These are the removable blocks that slot into the front of the fuse board. Inside each one is a length of fuse wire — the bit that melts if something overloads or shorts out, cutting off the electricity to that part of the house. Replacing the fusewire alone using ChatGPT and adhering to basic electrical safety rules took me 2 hours. Half an hour was taking the old fuse wires out (2 not 1, that’s bad) and the other half an hour was spent twisting with a manual screwdriver and the tiny screws kept falling out. ChatCPT4o was my bestest friend on this day. Now I knew how to do it, I’m thankful that each fuse carrier controls a separate area, like your lights or sockets. If one blows, that part of the house goes dark. You pull it out, replace the wire inside, and slot it back in. Simple in theory , fiddly in practice, but having the blu tacky reusable stationery essential, was essential.

Fuse Carrier Construction: What do Brass Terminal Points do?

These are the shiny metal screw terminals inside the fuse carrier, holding the fuse wire tightly in place at either end, creating a solid connection for the electricity to pass through (ahem, until it blows!). Breaking that link has parallels with the Portugal and the Iberian Peninsula blackout this week. Without a firm connection at these terminals, your fuse wire could spark, heat up unevenly, or fail to interrupt the power correctly. They’re small, but absolutely critical.

Bus Bar – The Copper Strip and it’s LIVE

This is the hidden copper strip running along the back of the fuse board carries the live current from the main switch to each of the fuse holders.

It’s how the power is distributed evenly across your circuits and this matters a lot
The bus bar is the unseen highway that connects the switch to every fuse. Without it, your fuse box would be a collection of disconnected parts. It also explains why every fuse holder is live — even when just one circuit is affected.

Wiring Paths (Red = Live, Black = Neutral)

What they show:
Red wires carry electricity from the fuse board to your appliances and lights. Black wires carry it safely back. These paths show the complete loop of a working electrical circuit.Why they matter:
Seeing how the current travels from the bus bar, through the fuse, along the red (live) wire, and back via the black (neutral) helps people visualise what’s happening behind the scenes — especially if they’ve never looked inside a fuse box before.