Cartridge Fuses in Domestic Fuse Boxes.

I have only met one out in the wild. They were never that popular.

I am not keen on cartridge fuses domestically due to the need for a large supply of spare fuses in case of an intermittent or hard to locate fault. A dozen spares could cost as much as an MCB.

In the late 1980s I helped as a teenager to put a few in, equally the hot wire boards were still more common, being cheaper, and I think the reign of the cartridge fuse as king was probably quite short - MCBs must have been coming in the 1990, and dominant by 2000 or so. In most cases the transition has been straight from various  noahs ark era stuff, to  BS3036 in the '50s to MCBs of some sort.

I remember the Wylex BS3871 press button MCBs with 1.5kA breaking capacity being a direct replacement for BS3036 rewirables They were just as unreliable after a fault and would have to be replaced. The MEM cartridge fuse came with its own plug in DIN rail cartridge which was and still is a neat solution.


Legh

I'd imagine cost. Both of the test gear to successfully test a circuit breaker at up to its breaking capacity, and more importantly, the cost of the breaker itself.   And this leads back to your point. Should the breaker not be designed to survive a possibly unlimited number of dead shorts at its rated capacity, or should the test be reserved for installation and at every EICR... with a decrementing counter on the breaker body itself somewhere? More expense. Breakers are a couple of pounds each, new, name brand, plus VAT. Designing in the ability to survive a fault AND continue operating would at least quadruple that.


All that's currently required is that a decent sample of the batch fails SAFELY in the event of a catastrophic fault.  If the internals of the breaker are trash... provided it didn't destroy the rest of the DB, and opened the circuit, it passes.


I actually like cartridge fuses for just this reason. Their MO is to destroy themselves, so they automatically get replaced. And are well proven.


But I'd posit that given the number in service, and the number of major problems caused by their failure... that MCB's have actually managed to pass that bar also?


Remember, functional testing of 'things that live in the CU' is only a thing because of RCD's, which can, by their nature, be tested under severe 'fault' conditions without actually endangering anything.


Sorry for the ramble :)

Kelly, either you are very old, or else you had an interest in wiring from a very early age. ?

The rats nest of green and yellow sounds like the supplementary bonding crisis of the 80s! <grin> Every bit of metalwork had to be bonded to every other, even if it was directly connected to it by a 22mm pipe because 'ptfe' tape :)


I think I pre date you by a few years because dad upgraded our wylex CU from rewireable to pushbutton MCBs that definitely WERE colour coded (I even have a few now in my collection). The later switch ones were also colour coded at first, but then they went to a grey toggle. We still have a few of the later ones on the van for elderly customers who struggle with rewiring fuses but insist that anything above a fiver is 'too expensive'. Usually put in gratis.

Perhaps surprisingly, the local hardware shop here still stocks 1361 fuses: (along with internal telephone cable with steel conductors.)

I may be correct in saying that they were compatible with 1mm cpc ring circuits, but MCBs are not.


Angram

I may be correct in saying that they were compatible with 1mm cpc ring circuits, but MCBs are not

My copy of the OSG would seem to agree!

 

My customer cut through his electric lawnmower flex in the garden. He blew the 15 Amp blue cartridge fuse in his fuse box. He sought a replacement and found them at a local hardware shop. He had to buy two in a packet. The cost was just under a fiver.

An advantage of the 13A plug system when supplied from a 30A fused circuit - the 13A (or lower) plug fuse should discriminate very nicely with the 30A circuit fuse, which in turn should discriminate nicely with a 60A (or higher) DNO fuse. The fashion for MCBs rather messed that up. Not all progress is an advancement.


  - Andy.