Dying Energy-Saver bulb blew out my lighting circuit

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Whew! The whizzing noise is most of that going straight over my head.

However:
1) Yes, I think I could cut out the shaded bit on the fusebox cover. (But wouldn't that detract from its value as an antique? I gather bakelite has become quite collectable recently...)

2) Re 5amp v 6amp etc. In the description of the Wylex plug-ins it says:
"The current carrying capacity of the cable should always exceed the current rating of the MCB to prevent damage". Does this mean that if I put a in 6amp MCB (but I don't think I will), would I have to get the lighting circuit cables changed as well?

3) Do the MCBs trip by magnetism? If so, could storing a box of tools with magnetised screwdrivers next to the fuse box affect it? Or boxes of toys that might have toy magnets or fridge magnets in them?

4) I've had a look round at similar topics on this site and there is one about 20amp fuse wire not being easily available. Would 4 pieces of 5amp twisted together do at a pinch?
 
1) ha ha

2) The cable used is probably rated at 18Amp, less deductions if enclosed, buried in insulation, in a wall, bunched in conduit, etc, but the 6A is generally considered interchangeable with 5A fusewire (unless, as on previous page, you have a poor earth. If you have an underground supply, and/or live in a densely-built town, I wouldn't have expected this to be a prob, but I am not up to date, so someone cleverer than me will probably be along in a minute).

3) Yes, no, no. there is a tiny coil, wrapped round a tiny piece of iron that it pulls on to create the trip. There is very tiny gap between them. Your magnetic screwdrivers are going to be very much weaker, and a hundred or a thousand times further away from the iron slug.

4) NO NO NO NO NO! You can easily buy a 15 or 16A breakers or fusewire, do you know what the load is on that circuit? 20A breakers are also still available, I thought screwfix sold them at about £7.50, if you really can't find one, and 15/16A isn't enough, i can find one in my antique collection.
 
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4) Er - more curiosity than a joke: 4 X 5 = 20, doesn't it? The 20amp carries the immersion only. I won't do it, honest - Wylex have 20amp breakers, but why would it be wrong? What would happen?
 
You can't depend on 4 x 5A wires twisted together being 20A. I don't know what it will be, but it won't be 20.

If it's for an immersion heater, 15A would be correct (the fuse carrier ought to have two blue spots on it).
 
There are alsorts of reasons why 4x5 doesn't equal 20 in fuse terms, for example, is it going to break the same way as a 20?, I can't answer that, but I'd suggest the answer would be that there would be some differences*, a lot of effort is put into designing fuses to ensure for example they will break the current upto their breaking capacity properly, that they will limit the let through energy to a low enough value, etc

granted the 3036 is a bit off a crap design, its performance can be affected slightly (or a lot if they installed fencing, instead of fuse wire!) by who wired it, and its only suitable for breaking low currents becuase its got no sand to break an arc.

The point I'm trying to make out, is fuses are more complicated than they first look, and messing around with them, using them outside their design paramatures, you really don't know how its going to behave

*for example the wire would have a greater surface area, which means that its further away from true adiabatic opperation (heating up so fast that the heat can't disapate at all) than the normal wire which would result in a higher I²t let through energy


P.S. As John says, your immersion should be on a 15A/16A circuit
 
It's yellow, no blue dots. I think this bit of the wiring was done when the central heating was put it in, maybe it has the pump etc on it too. I've never thought to check. The central heating was put in 20 years ago.
 
One way round, is to use a 13amp fuse-connection unit for the immersion, if it's 3000 watts rated. installed next to the consumer unit.
 

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