Fuse sizes!

[westie101]

Now you know!

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[securespark]

I have seen foil galore in all sorts of fuseholders, from plugs to fuse carriers to cut-outs.

I have seen a sawn-off 6" nail in a plug feeding a 3.5kW immersion.

I have even seen a table knife jammed in a Bill switch fuse, in the days before I carried a camera...

Bet that cow ain't laughing now...

 

[Jackrae]

And I've seen the mess a piece of galvanised steel wire makes after its blown - not a pretty sight.

 

[ericmark]

I always remember finding a Lucas 2TU trailer relay with a aluminium rod where the fuse should go and I started an inquiry as to how it got there.

However it transpired since the relay was not easy assessable the manufacturer had fitted the aluminium rod and also a fuse in a more assessable location.

One can get fuse links often white designed to go in the neutral so the neutral is not fused.

But the visible ones are not so bad at least you can see what has been done. On one job with bottle fuses the diameter changed as the sizes went up both of the nose contact and whole fuse and the maximum for board was 25A but needed around 35A so the electrician had carefully dismantled a 35 amp fuse and put the foil inside a 25A fuse and refilled with sand.

I as a young electrician was pulling my hair out fuse had blown could not find a fault and the spec said 35A but they would not fit holder. I also put a 35A foil in the 25A fuse to keep the freezer going but was rather worried about what I had done so owned up when the electrician returned from leave.

 

[JM2]

I think that ring pull is over-rated.

 

[kai]

This the approach that DNO's use when sizing their service cables, Oh an 800amp sub-station fuse will protect a 25sq.mm. service cable off their main, without sub fusing!

 

[danechip]

I have seen a sawn-off 6" nail in a plug feeding a 3.5kW immersion.

How did you know it wasn't a 5" nail ?

 

[DaftPunk]

This the approach that DNO's use when sizing their service cables, Oh an 800amp sub-station fuse will protect a 25sq.mm. service cable off their main, without sub fusing!

That supply is properly fused. It relies on the substation fuses for fault protection and the cutout fuse for overload protection.

No different to the now slightly out of date switch fuse fed from a busbar chamber arrangement as found in virtually all older industrial installations.

 

[ericmark]

I have seen a sawn-off 6" nail in a plug feeding a 3.5kW immersion.

Is this a problem? If one looks at the old method of a 15A fuse feeding a 15A socket and plug at the immersion if the 15A plug and socket was damaged finding a replacement at short notice may be hard. Using a nail in a 13A plug would mean still protected by 15A fuse in consumer unit but no fuse to over heat the 13A plug. All fuses produce heat and it is the heat from the 13A fuse in the plug which has always been a problem more so since the plastic bits were added to pins which reduced the heat which could be transferred to the socket. Clearly if no 15A or 16A fuse or MCB feeding socket then a problem. But with fuse or MCB in consumer unit it would be just the same as the aluminium rod I found in fuse holder of Lucas 2TU flasher relay.

I still think it's wrong, but it is not necessary a problem.

 

[kai]

Will a 16amp waterproof Commando type plug and socket be a better bet on an Immersion Heater?

 

[EFLImpudence]

Assuming it is wired conventionally all that is required is a 20A DP switch.

 

[JohnW2]

Will a 16amp waterproof Commando type plug and socket be a better bet on an Immersion Heater?

Why waterproof, why 16A and why a plug and socket at all?

Kind Regards, John