Appliance fuses

[Mikefromlondon]

I'm not the 4amp washing machine guy! Mine have 13A fuses and ~2kW heaters inside and no, I haven’t changed them from 13A to 10A even though they may still operate with a 10A fuse.

apologies for my mixup!

 

[ban-all-sheds]

So I argued that heat detectors would be pointless as they only work on after a fire has broken out. Apart from saving your life it does not save your property.

That's no good. What's the point of being alive if your house has burnt down?

A smoke detector does both, though it may become nuisance in a kitchen, better safe than sorry!

Surely what you want in a kitchen is a rate-of-rise heat detector?

So my choice would be to fit a 5A for a 4 amp load rather than a 13 amp from the standard stock.

Which will happily allow >1kW of heating to take place within the load for as long as it takes to be destroyed by fire.

 

[Mikefromlondon]

You got a point there!

secondly, as for rate of rise heat detectors, I am presuming they monitor the ambient temperature and if the temperature starts to go up rapidly they send off the alarm, though how much rise in temperature over a given time, can they do this, without the fire sweeping the whole house. May be worth looking into them.

 

[Ray Tay]

WhydidIstart, However I have also had an appliance become faulty and catch fire = house fire and the 13A fuse did not blow. Interestingly when the fire brigade dragged the unit outside the mains lead was fine I'm not saying a lower, or more closly 'matched' fuse would have prevented the fire, but it may have done.

You hit the nail on the head. erickmark speaks sense on this thread as well. The safety level is obviously higher when a lower rated fuse matched closer to the appliances current rating is fitted. Lots of people deal with electricity in their jobs and know it very well but are NOT electricians. They do not deal in building wiring, but they know electricity for sure. It was clear to me that electricians stop at the appliance as that to them is not their responsibility. They are only concerned with the wires and flexes to it. That to me is irresponsibility. As I have stated, and a few back my view on here, the appliance current rating must be taken into account. If an appliance draws 4A then a 13A fuse fitted in a plug is irresponsibility and raises the fire risk. There are many ratings of fuses available for plugs, not just 3A and 13A. And that is for a reason, but many can't see it.

MikefromLondon, so like you said to protect an item that needs 4 amps, one can safely fit a fuse rated slightly higher but one should not fit a 4 amp for a 4 amp load, danger of overheating. So my choice would be to fit a 5A for a 4 amp load rather than a 13 amp from the standard stock.

Spot on MikefromLondon.

ericmark, So if we consider domestic equipment and fire risk, then for a vacuum cleaner limited to 1.6kW or 7 amp clearly using a 7 amp fuse is too small, but using a 10 amp fuse it will possibly rupture that little bit quicker than a 13 amp fuse which could mean it ruptures before it goes on fire

Spot on Eric.

 

[bernardgreen]

There are many ratings of fuses available, not just 3A and 13A. And that is for a reason, but many can't see it.

THere are also many types of fuse ( fast acting, delayed action, anti surge ). How would you address the matter of fuse fatique ( tired fuses ) when the fuse is carrying current at its rated limited with the fusible link at high temperature. ( the fusible link can be much hotter than the external surface ). Five amp load, 5 amp fuse, ( standard plug fuse ), how long before the fuse reduces to a 4 amp fuse and then blows when there is no fault, just the normal five amp load.

If an appliance draws 4A then a 13A fuses fitted in a plug is irresponsibility and raises the fire risk.

If the appliance has a fire risk then the appliance should be designed with its own current limiting fuses or other protection.

9 volts from a PP3 battery can create a serious fire, current is about half an amp. If you don't believe it look at this video

 

[Risteard]

Risteard, Once again Ray Tay, you haven't the slightest clue what you are talking about.
It seems a whole raft of us do not know what we are on about to you. BTW, doesn't Ireland use the European system?

Depends what you mean by the "European system". We are all in Europe. I presume you mean the Continental system, and then the answer is no.

And we use different Rules/Regulations on both sides of the border. In the north we use BS 7671, and indeed my Apprenticeship was to that Standard. So I'm afraid that I am very familiar with it.

 

[Ray Tay]

If you look at current ratings of appliances, you will find that very few will actually need a 13A fuse. Most washing machines are closer rated to 10A in the plug.

 

[eveares]

The only preferred ratings in the Standard are 3A and 13A. If using other ratings you would need to check the manufacturer's data for Zs etc.

Using a fuse lower that 3A/13A and having to check for Zs is nonsense. A Fuse rating lower than a 3A/13A fuse respectively is not only going to have a higher allowed Zs value, it will blow quicker than the higher value 3A/13A fuse. Using a lower rated fuse wont compromise safety providing the appliance is rated at or lower than the fuse used.

I often use 2A vs 3A fuses in sensitive equipment like alarm panels to give a extra margin of safety. Also 0.75mm² flex is rated at 6 Amps; Now say it's got a 5A load applied through it, both 3A and 13A fuses are unsustainable, thus the need for plug top fuses other than 3 and 13 amp.

 

[EFLImpudence]

They do not deal in building wiring, but they know electricity for sure. It was clear to me that electricians stop at the appliance as that to them is not their responsibility. They are only concerned with the wires and flexes to it. That to me is irresponsibility.

No it isn't.
Plus we will follow the manufacturer's instructions as to what fuse to fit etc.

It seems to me, your gripe, if indeed a genuine one is, in fact, with the manufacturers for making products which catch fire when installed as they instruct.

As I have stated, and a few back my view on here, the appliance current rating must be taken into account. If an appliance draws 4A then a 13A fuses fitted in a plug is irresponsibility and raises the fire risk.

No it doesn't - see above.

There are many ratings of fuses available, not just 3A and 13A. And that is for a reason, but many can't see it.

...but there aren't that many cable sizes. See above.


What would you do about a cooker which is an appliance containing many more smaller appliances?
It needs a large fuse to be able to work as intended but each part is wired with (very) small wire sizes.

As you cannot use a small fuse, would you consider it necessary to rewire the cooker with a minimum of 4mm² conductors - perhaps 6mm²?

I don't see how you could be happy when not doing so.

 

[Risteard]

Using a fuse lower that 3A/13A and having to check for Zs is nonsense.

It's not nonsense. It is not specified in the way that 3A and 13A are because it isn't a recognised rating.

 

[Risteard]

I often use 2A vs 3A fuses in sensitive equipment like alarm panels

They aren't to BS 1362 though, so you're talking about a completely different type of fuse.

 

[Ray Tay]

EFLImpudence, it seems to me, your gripe, if indeed a genuine one is, in fact, with the manufacturers for making products which catch fire when installed as they instruct.

You are there. Some makers are pretty irresponsible. But responsible installers should use common sense and apply fuses using a professional approach. I am sure you agree with me that an appliance having a 13A fuse when rated at 4A increases the fire risk.

 

[EFLImpudence]

Are you ignoring the cooker question, then?

Some makers are pretty irresponsible.

So, your gripe IS with the manufacturers then.

But responsible installers should use common sense and apply fuses using a professional approach.

Why don't they? It would take NO effort.

I am sure you agree with me that an appliance having a 13A fuse when rated at 4A increases the fire risk.

It's nothing to do with the rating.

Perhaps, with Amendment 3 out now, all products should be made of non-combustible material.

 

[endecotp]

I often use 2A vs 3A fuses in sensitive equipment like alarm panels

What do the manufacturer's instructions for those panels say?

And what do you mean by "sensitive" in that quote?

 

[eveares]

It is not specified in the way that 3A and 13A are because it isn't a recognised rating

Yes they are recognised. In the BS1362 complaint range of fuses, you get 1A, 2A, 3A, 5A, 7A, 10A, and 13A. Historicly 3A, 5A and 13A have been most common.

They aren't to BS 1362 though

BS1362 2A Fuse

• eveares
• 30 Mar 2016

Also What fuse would you personally use then if you had a 5 Amp load over 0.75mm² flex then? 3A is to low for a 5A load, and 13 Amps through 0.75mm² flex in lengths over 2 Meters and when not used with a portable appliance is not allowed either.