Should fuses be in plug tops

LeBash

adrian92 wrote: »

Thanks for that. I wonder. though, if the 13A fuses were used to replace the failed fuses with a lower rating, such as 3A fuses?

If someone walked in and asked for a 13A fuse, they got a 13A fuse. If they brought something in with a 3A, 5A, 10A or 13A we would test the fuse and replace it with same.

It might seem a pain but the thing has done its job.

RCDs are a pain if you dont know what it has potential protected you from as well.

Gerry T

From memory 1.5sq can carry max 17amp and 2.5sq 27amp. This gets reduced depending where the cable is installed, if its run where it cant dissipate heat then the cables current carrying capacity is reduced.
As mentioned your sockets are wired in 2.5sq and a ring main, so one conductor carrys 2/3 of the current and the other 1/3 on average. The 32a mcb is protecting both cables but if you plug in a device with 1.5sq then the mcb wont protect that cable. This is why there is a fuse. Max at 13a to allow for tolerances in the current capacity of the 1.5sq (say 14 to 17amp).

2011

I supposed the other point is that RCDs are always described as “supplementary” protection, as such they should complement other types of protection rather than replace them.

Bruthal

LeBash wrote: »

If someone walked in and asked for a 13A fuse, they got a 13A fuse. If they brought something in with a 3A, 5A, 10A or 13A we would test the fuse and replace it with same.

It might seem a pain but the thing has done its job.

RCDs are a pain if you dont know what it has potential protected you from as well.

Well if the fuse is replaced and the item works away without a problem, it probably didnt do any job except failed.

Some say they dont fail without a fault. My opinion is that they do.

Ger Roe

Bruthal wrote: »

Well the rcd will sometimes save a fuse from blowing.

But many devices dont have any earth conductor in their leads, so it will do nothing on those in terms of fault tripping.

So they dont really reduce the need for plug fuses, if there is a need for them.

Exactly. There are some household devices that might not have an earth connection and therefore the RCD may not provide protection. The purpose of an inline (or plugtop) fuse is not specifically or exclusively to protect the device, it is there to protect the user - either from shock or fire risk.

A badly worn figure of 8 mains device connection cable does not have an earth, so may not trip an RCD, if faulty. But an exposed (worn) power cable, or an internal live short to an unearthed chassis, could give a shock to the user, or cause fire... in that case the plug top fuse might be your only protection.

listermint

adrian92 wrote: »

Well,

It would be of interest to me to know if anyone can give an example of how a 13A fuse in a plug top has provided electrical protection

Genuine question.

Have you ever seen a narwhal whale?


Does that mean they don't exist ?


Just because you have not personally witnessed something doesn't mean it isn't true. It's the epitomy of world revolving

Bruthal

2011 wrote: »

I supposed the other point is that RCDs are always described as “supplementary” protection, as such they should complement other types of protection rather than replace them.

Yes we know that once some read in a book that the 30ma RCD is to reduce electric shock risk, (which it is), then that is all they do because the book/google says so.

But as is often seen with washing machines as an example, they sometimes show up faults or leaks as well.

Ger Roe

Bruthal wrote: »

Well if the fuse is replaced and the item works away without a problem, it probably didnt do any job except failed.

Some say they dont fail without a fault. My opinion is that they do.

In that case, there was an unsafe increase in current drawn and the fuse did it's job. If the unit continues to operate when the fuse is replaced, it should still be checked for safety. Maybe the fault is intermittent (could be a loose wire internally), maybe the fault takes time to manifest itself... a component heating up.

The fuse blew because it's current rating was exceeded. It did it's job... now the device should be checked to determine why that happened and if it might happen again.

I have heard people say that fuses are always faulty because they keep blowing for 'no reason'. There is always a reason and if they keep blowing, you still have a problem and the problem is not faulty fuses.

0lddog

For much of my life I was untroubled by plug top fuses as the norm was https://picclick.co.uk/Vintage-Old-Art-Deco-Brown-Bakelite-Plug-3-264273257348.html.

Equally I was untroubled by such nonsense as earthing rods for domestic house supplies.

Just like airbags in cars, there is no need for plug top fuses.....












untill they are needed

( BTW do the regs allow 5A socket lighting circuits ? )

Bruthal

listermint wrote: »

Just because you have not personally witnessed something doesn't mean it isn't true. It's the epitomy of world revolving

Tomorrow is the solstice, last week was the earliest sunset. Whats going on:D

Bruthal

Ger Roe wrote: »

In that case, there was an unsafe increase in current drawn and the fuse did it's job. If the unit continues to operate when the fuse is replaced, it should still be checked for safety. Maybe the fault is intermittent (could be a loose wire internally), maybe the fault takes time to manifest itself... a component heating up.

The fuse blew because it's current rating was exceeded. It did it's job... now the device should be checked to determine why that happened and if it might happen again.

I have heard people say that fuses are always faulty because they keep blowing for 'no reason'. There is always a reason and if they keep blowing, you still have a problem and the problem is not faulty fuses.

Fuses can fail without ever been overloaded. They deteriorate over time.

Loose connections dont cause increase in current unless its motor based or a huge incandescent lighting bank, and if that was the cause, the motor would blow the fuse when the device is started. If the fuse holder itself is loose, the fuse can overheat.

The fact is, plug fuses are cheap mass produced items which fail on occasion.

2011

Ger Roe wrote: »

Exactly. There are some household devices that might not have an earth connection and therefore the RCD may not provide protection.

Remember the RCD will be providing protection to the entire circuit that an appliance is connected to, not just the appliance.

Also just because an appliance is double insulated does not mean that an RCD is not providing a level of protection to the end user.

adrian92

Thank you all for your comments.
Quite a diversity of views.

I wonder is there a general consensus if we should have simpler plug tops(with no fuses)?

CelticRambler

Bruthal wrote: »

Plug top fuses are a debatable topic though.

adrian92 wrote: »

Quite a diversity of views.

I wonder is there a general consensus if we should have simpler plug tops(with no fuses)?

Move to France: probably the only thing there's 100% consensus on here - no fuses in plugs. It doesn't even come up as a topic for debate during the most heated dinner-table discussions!

adrian92

I simply asked a question about fuses.

Most have addressed my points.

A few have made disparaging remarks about me - this is not the sense of this forum. Be critical , my all means, my point ; but not personal , like to go away to another country, as was suggested.

This forum has always attempted to avoid any form of comments like this.

I would ask the Moderator to consider (I do not want to ask a question about fuses if I am going to be subject to ridicule, by a few)

Bruthal

CelticRambler wrote: »

no fuses in plugs. It doesn't even come up as a topic for debate during the most heated dinner-table discussions!

Neither does earth tags on trunking. Are they needed?

CelticRambler

Bruthal wrote: »

Neither does earth tags on trunking. Are they needed?

All trunking is plastic (if installed according to the regs) so ... no. Tags on copper pipework if you have it (quite rare these days), and you're supposed to earth foil-backed roof insulation (few do); otherwise it's direct lines from sockets via the main board to the rod outside and nothing else.

What really throws our British and Irish guests off balance, though, are the light switches inside the bathroom. :eek:

Stoner

All.

I'm going to close this thread. It was answered within the first 10 posts.

Yes some of the answers later on were a bit Ott, however some of the responses to the correct advice went beyond a question about understanding the need

A 5 amp fuse in a plug top can help to protect a device rated at 5 amps but fed from network of cable and fuses that could allow 20 amps to the device.

Different types of switchgear protect against different types of fault. Fuses in plug tops do not react to all the different types of electrical faults that can happen.

That is accurate. Some cable networks could allow over 30 amps and in these ring circuits 13 amp fuses protected the device and the leg of the cable the left the ring to feed a socket.

It's not always obvious when looking at an outlet , but stepping down the current into a device is very useful, even if a device upstream reacts or reacts faster to certain types of fault.
That's it really, the fact that other countries do or don't have them, or that someone never had to change them does not form the basis of an argument to not use them.


This started out with a general information enquiry, it was answered in the spirit of the forum

It ended up challenging the use of fuses, rather than understanding them.