Wylex Standard fuseboxes

The Wylex Standard range of fuseboxes has been available for decades. Literally millions have been installed in the UK.


6 way Wylex metalclad fuseboxThese fuseboxes are well designed and made. Although they are still manufactured (2008), the design is no longer suited to modern installations. The main drawbacks are no facility to fit RCDs, and most of them are limited to 30A per circuit.

The example shown here is a metal cased flush mounted unit from the 1960s. Originally this would have contained rewireable fuses, but has been 'upgraded' with push button circuit breakers, probably mid-1980s. One of the breakers is missing. Left to right, the remaining ones are 30A, 30A, 15A, 5A, 5A.


Both metal and plastic versions are available. Newer plastic ones are cream coloured, older ones may be dark brown. The metal ones are generally grey.

Older boxes were made with no back, and a wooden frame. Any example like this should be replaced. The wooden frame is flammable, and since fuseboxes are often mounted on wooden boards, the backless types are dry kindling waiting to be set on fire. This is not an exaggeration either - consider that a short circuit will cause a rewireable fuse to vaporise, spraying molten copper from the fuseholder.

A paxolin back panel was available, however as this was an optional item, many boxes were fitted without them.

The majority of these boxes cannot have devices over 30A fitted. Those which can are easily identified, as one of the fuseways will have a different appearance.
Normally, the high rated fuseway will have additional contacts and either be next to the main switch, or be separate to the other fuseways. In all cases, the plastic moulding behind the contacts has an extra cutout section near the top right. Devices over 30A have a notch which fits into this cutout, the idea being that this notch prevents the device being fitted to a normal fuseway.

Unfortunately, some people just cut the notch away. Some newer devices don't even have the notch - quality design thrown away and ignored!

Connecting a high current load such as a 10kW shower to one of these fuseboxes results in various failures:
1. The fuse contacts overheat and become loose.
2. The plastic holding the contacts becomes discoloured and brittle.
3. The loose contacts eventually spot-weld to the fuse carrier.
4. Removing the fuse carrier is very difficult. Applying excessive force rends the contacts out of the backing plate.
5. The fusebox is a total loss.

Fuses and other devices

Three types of devices can be fitted to these fuseboxes. They are easily changed simply by pulling out the fuse or breaker, and removing the plastic shield which is fixed with a single screw.

Rewirable fuses

Probably the most common on older installations, these contain a small ceramic holder through which fusewire is threaded. Available in four types (5A, 15A, 20A and 30A). These have significant problems, the main one being the wrong size fusewire can be fitted. If no fusewire available, nails, hairpins or just about any metal wire can be fitted. This results in a dangerous situation, and even with the correct wire available, it can still be fitted incorrectly.

Cartridge fuses

These have a replaceable cartridge fuse. Each rating is a different physical size, preventing the wrong type being installed. Available from 5A to 45A

These can still be misused - the most common bodges being replacing the 5A fuse with one from a plug - while similar in size, the fuses are not exactly the same. This can lead to the fuse holder being damaged.
Wrapping the fuse in foil, or shoving bits of wire in there is another dangerous bodge.

Minature circuit breakers / MCBs

These have a lever or button, so that in the event of an overload or fault, the device can be reset simply by moving a switch.
Several types exist, the oldest having a round button, newer ones having coloured levers, and the most recent with black levers. Various ratings available up to 45A.


6 way Wylex metalclad fusebox without cover Although available in various styles and sizes, the internals are usually very similar. This example shows the main switch at the right side, with the live and neutral supply connected to the top of the switch.

The neutral block is positioned to the left of the main switch, and the live copper busbar extends from the bottom of the main switch across underneath the six fuse positions.

Circuit wiring is connected to the top of each fuseway, neutrals all go to the neutral block, and earth wires connect to the separate block at the top left.

This one only has a few earth wires, as most of the circuits are wired in MIMS, the earth being via the metal sheath of the cable and the metal fusebox cabinet. The brass cable glands are visible underneath the circuit breakers.

To upgrade - or not?

The plug in circuit breakers are still readily available, and are easy to fit. However it is really not worth replacing these, as the benefits are minimal.

The only real advantage is that the circuit breakers react quicker than a fuse. They do not provide any protection against electric shock.

If you are considering these plug in breakers because you are always having to replace fuses or fuse wire, your installation has significant problems. Fuses only fail if there is a fault. Putting a circuit breaker in there will not solve overloads, faulty wiring or any other problems.