Replace Blown Fuse Wire and Retrofit 1970s Bakelite Fuse Box 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.
Spoiler: it was just me. The street carried on as normal while I stood in the hallway flicking switches like a confused DJ.
Can I Pull the Fuses Out Safely to Examine the Wire Now I’ve Flipped the Breaker Back On?
Short answer: no, not safely — not with that fuse box.
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:
- 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.
- 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.
- 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.
- 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.
- 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
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 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.
Can I Pull the Fuses Out Safely to Examine the Wire Now I’ve Flipped the Breaker Back On?
Short answer: no, not safely — not with that fuse box.
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:
- 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.
- 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.
- 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.
- 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.
- 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.
Should I Use Spray to Clean My Fuse Box?
Before you grab that can of 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.
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. Here’s the quick rule of thumb:
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 Secret Weapon for Safe Cleaning
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.
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.
This isn’t just about aesthetics — clean contacts conduct better, run cooler, and reduce the risk of intermittent faults or overheating. Give everything a careful once-over, and let it air out fully before restoring the power.
Threading the Fuse Wire and the Brass Screw Ballet
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.
That tiny brass terminal screw is deceptively heavy for its size — and 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.
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.
This isn’t just about aesthetics — clean contacts conduct better, run cooler, and reduce the risk of intermittent faults or overheating. Give everything a careful once-over, and let it air out fully before restoring the power.
