Appliance fuses

[JohnW2]

A traditional loop-in ceiling rose could carry the entire circuit current. Ditto switches if looping there. Ditto any compliant JBs.

All true, but that "entire circuit current" is, under normal (non-fault) circumstances, at most the design current of the circuit, even if (as obviously is permitted) the In of the circuit's OPD exceeds that design current.

Or are you saying that the OPD is not there "only to protect the cable" but is also there as a perceived (but not very effective!) 'current limiter" to 'protect' 6A-rated accessories from currents greater than their rated figure??

Kind Regards, John

 

[ericmark]

If you look at my cooker and compare with the tumble drier which went on fire we see how it is easy today to include safety devices but only the more expensive items have them fitted. My cooker has two levels of safety shut down due to over heating. If the pan hit first temperature it is assumed user error and the heat is auto reduced, at the second temperature it is assumed fire and whole appliance shuts down. Between that and timers to limit how long a ring is used for, no red hot parts, auto boil then simmer, auto switch off when pan is removed, and child locks on the control knobs the cooker has about as many safety features as one could include. Plus a flat ceramic hob so pans are also very unlikely to get knocked over, and since no heat from hob it is direct into pan handles can be super short so again nothing to knock and cause a spillage.

However some people still cook on gas! That dangerous it was banned in many flats after the Ronan Point gas explosion. No ifs or buts it is simply not safe, but we still use it.

It seems this is part of human nature even after VW were caught cheating people still buy VW.

The tumble drier fires is not new, they have been going on for years, using a refrigeration unit to dehumidify is clearly safer than using a heater, not sure I like the idea of using cold water to dehumidify as with some washer driers but again the tumble drier can be designed to work safely. However I am guilty of going into the shop and selecting the model on price without looking at their record.

Servis, Hotpoint, Whirlpool Indesit and Creda have all hit the news. There are two simple ways to stop the fires, one is use a mineral insulated heater which has a larger surface area so does not get as hot, the other is to use heat sensors to auto close down the device. How a condenser dryer has a heating element is another question? However although one can get heat fuses common in fan heaters this fuse has to be inside the appliance. There is really no way a fuse exterior to the appliance will help. A RCD may remove the supply as insulation fails due to the fire but likely too late.

As to unattended use well if you install one in the garage in case it goes on fire so there is at least some protection against fire then you are hardly going to then stand in a garage watching it. If I had one of the units then it would be a case of replacing and remembering never to buy that make again. Likely they will now change the name.

No Sir this is not a VW it's a Skoda they were called Laurin & Klement and were nothing to do with VW.

 

[ban-all-sheds]

Are you always spoiling for an argument?

No, but other people are.

WTF are you on about?

The truth.

Have you installed any of their stuff?

No.

I strongly suspect not, otherwise you would know they are neither flaky nor without the necessary protection.

Then why do they require an external protective device for their product? If it was not flaky, and did have the necessary protection for itself within itself then it would not need it.

Please clarify your statement.

Leaving aside the practicalities of terminating large cables, if the equipment was was not flaky, and did have the necessary protection for itself within itself then it ought to be just as safe on a circuit fused at 200A as 2A.

If it isn't then it is flaky and it does not have the necessary protection for itself within itself.

 

[ericmark]

Yes, but, as in the rest of the thread, I don't think that is a genuine expectation.
The accessories and pendant drops may be 6A but they only carry the current to individual items.

A traditional loop-in ceiling rose could carry the entire circuit current.

In the same way as a socket may carry 32A?

Granted the loop has separate terminals.

Only in hospitals and that is really a special case. The red hospital plug with no fuse is only used where if the equipment fails it could be life threatening. They are not in general use.

 

[WhydidIstart]

A smaller fuse provides more protection. That is obvious.

I think we are on the same page now and I have already agreed with you that fitting smaller fuses is not necessary.

To be clear I am not saying that it is necessary to fit smaller fuses.

The bullet-resistant glass analogy is an interesting one and I can see what you are saying - if the glass already protects you, then yes making it thicker would make the glass more protective, but what would be the point if you are already protected?

I think where the analogy falls down is that the occurrence of faults and protection of a fuse is not a completely black and white = protected or not situation. We have over 64 million people in the UK (and so many more appliances) and with such vast numbers of people, statistically there will be 64 'one in a million' chance events happening every day.

So using the bullet-resistant glass again, I suggest a more realistic analogy is to say the glass is 99.9% bullet-proof....but one in every 1,000 bullets will come through and spoil your day. By changing your fuses to give more protection, you improve your glass to be 99.95% bullet-proof. So now statistically only one in every 2,000 bullets will come through. Personally I would probably step in front of that 99.95% glass rather than the other glass. Now someone tells me I have to change the fuses in every plug in my house if I want to step in front of that better glass and suddenly I'm not so sure it's worth the effort...

Back to real life and I was in the house when my tumble dryer caught fire. Thanks to a fire rated door that happened to be closed, a vigilant member of the public and our excellent fire service plus my then central location, the fire was limited mostly to 1 room and there was only property damage, no injuries. As a result I have moved the tumble dryer to a brick built outbuilding. Do I think it is possible that lower rated fuses could, in some specific circumstances provide a degree of better protection for appliances? Yes. Have I gone round and changed all my fuses? No.

 

[EFLImpudence]

Ok. I can't remember where it started so perhaps we have been at crossed purposed

 

[WhydidIstart]

ericmark mentioned the unfused hospital red plugs, just out of interest this is an old NHS Scotland guidance note regarding the plugs. Basically saying that the cable must be 4mmsq or larger and hence the protective device supplying the outlet provides adequate protection when they are used.

www.hfs.scot.nhs.uk/publications/PSAN9504.pdf

 

[securespark]

In this instance, you have done a good job making yourself look like someone wanting to pick a fight.

To blame others is just puerile.

I don't believe the 2A fuse is for their product as it has several fuses on the PCB.

Why did you assume it was?

I dunno about other security installers, but I have always fed my security panels via an FCU, except in one case where I ran it via a 2A MCB direct from the board.

See page 11 for details of electrical supply:
https://www.tlc-direct.co.uk/Technical/DataSheets/Ade/4pi175_A-G3_inst.pdf

 

[SimonH2]

Returning from the principle to real life, I had an appliance where the protection failed and it caught fire. Yes, it may have been ignition of fluff, but shouldn’t an appliance such as a tumble dryer that produces fluff be designed not to set fire to the fluff!? Of course it should, but in my case something went wrong which lead to it catching fire which should never have happened – but it did.

And there is currently a brand subject to a recall for exactly this problem. AIUI owners have been told "it'll be fixed sometime, but until then never use it unattended".
Similarly, many years ago, I recall a talk where engineering apprentices were talking about their experiences going into the working world. One was working for British Rail (so that dates the talk !) and described a project she worked on. IIRC it was a sleeper carriage, and there complaints of a burning smell usually followed by the heating failing. After analysing the system, it was found that the thermostat was in the return air path, before the heater. If the return air flow got obstructed, the thermostat failed to turn off the heater, which overheated until eventually a badly placed overheat trip triggered - the root cause being that the overheat protection was not in the right place - as it seems may be the case with the tumble driers on recall.

All true, but that "entire circuit current" is, under normal (non-fault) circumstances, at most the design current of the circuit, even if (as obviously is permitted) the In of the circuit's OPD exceeds that design current.

Or are you saying that the OPD is not there "only to protect the cable" but is also there as a perceived (but not very effective!) 'current limiter" to 'protect' 6A-rated accessories from currents greater than their rated figure??

Well that's an interesting question.
I wonder if there are still people who plug irons or vacuum cleaners into the light socket ? I believe it used to be common in the early days when lecky was basically a light in the middle of the ceiling (and I'd guess in only some rooms).
While it may not be common, I;m sure there are probably people who will use a light socket like that - and if the OPD allow it then ...

 

[JohnW2]

Well that's an interesting question. I wonder if there are still people who plug irons or vacuum cleaners into the light socket ? I believe it used to be common in the early days when lecky was basically a light in the middle of the ceiling (and I'd guess in only some rooms).

It was certainly the norm with my grandparents - including 'Christmas Trees' of adaptors dangling from the lampholder, to enable multiple loads to be plugged in.

While it may not be common, I;m sure there are probably people who will use a light socket like that - and if the OPD allow it then ...

If one believes that a circuit's OPD is only there to protect the fixed wiring (and if it has an appropriate rating fro that fixed wiring), then what is the problem with that? ... as far as the cable and the OPD are concerned, that's not conceptually really any different from someone plugging half a dozen fan heaters (or whatever) into a 32A sockets circuit.

The absence of an earth connection at the lampholder is obviously an issue, but nothing to do with the purpose/function of the OPD.

Kind Regards, John

 

[ban-all-sheds]

I don't believe the 2A fuse is for their product as it has several fuses on the PCB.

Why did you assume it was?

Because they ask for it. Why should their equipment care what the upstream fuse is? Why would the maker care enough to specify it if it made no difference?

See page 11 for details of electrical supply:
https://www.tlc-direct.co.uk/Technical/DataSheets/Ade/4pi175_A-G3_inst.pdf

I don't doubt that they specify it.

My point is that given that they do, it can only be because they feel that their equipment needs it. And if it needs a particular OPD on its supply it can only be because it doesn't have adequate protection without it.

Unless, of course, they are in the habit of putting in requirements for no reason whatsoever.

 

[Risteard]

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[Ray Tay]

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[Ray Tay]

ericmark, However some people still cook on gas! That dangerous it was banned in many flats after the Ronan Point gas explosion. No ifs or buts it is simply not safe, but we still use it.

Gas was banned in Ronan point because the building was system built. If there was an explosion the building is not strong enough to survive intact. Since the Ronan Point explosion, gas safety regs and appliance have increase substantially. All cooking hobs need flame failure lock outs. Similar on water heaters and boilers. All gas appliances have flame failure lockouts. I would put gas appliances 'generally' safer than electric appliances. As been highlighted here, the innards of many electrical appliance leave a lot to be desired. And the exterior fusing as well.

Gas cooking hobs are not banned in flats at all. Gas is very safe to cook with. 14 million gas consumers says so.

I agree with you that in using a refrigeration unit (heat pump) to dry clothes is clearly safer than using an element heater. They are available and a lot cheaper to run as well. They are reliable as they use proven fridge technology.

 

[ban-all-sheds]

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