Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric fire at a potential difference of 240v

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric fire at a potential difference of 240v
1150/240=4.79 so theoretically a 5A fuse shoud do.
--

Graham.
%Profound_observation%

On Mon, 19 Mar 2018 08:27:31 -0700 (PDT), whisky-dave
wrote:

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric fire at a potential difference of 240v

Assuming you mean at the BS1363 plug then the fuse should be sized to protect
the cable.
--

whisky-dave pretended :
Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric fire at
a potential difference of 240v

5amp ought to cover it, but it is very tight. If it fails find a 10amp.

On Monday, 19 March 2018 16:11:42 UTC, The Other Mike wrote:
On Mon, 19 Mar 2018 08:27:31 -0700 (PDT), whisky-dave
wrote:

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric fire at a potential difference of 240v

Assuming you mean at the BS1363 plug then the fuse should be sized to protect
the cable.
--

Nice, that's the sort of answer I'd expect :-)

But this was a question given to students doing our science foundation course where they are expected to say 5 Amps. (a student has left their marked paper (mid semester test) in the lab so I thought I'd have a look).

I have also been told that H&S state that consumers/users should only use either a 3A of 13 amp fuse in a plug and that is what we as technicians have been told to use, even though I have loads of fuses including 1A, 2A, 5A, 7A, 10A and 13A


https://www.rospa.com/home-safety/uk...hoosing-fuses/

On 19/03/2018 16:15, Harry Bloomfield wrote:
whisky-dave pretended :
Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric
fire at a potential difference of 240v

5amp ought to cover it, but it is very tight. If it fails find a 10amp.

It isn't *all* that tight in practice but the plug will run slightly
warm. A nominal 5A fuse will take nearly 20A to blow in the first second
and will probably support a current of 7A almost indefinitely. eg.

https://docs-emea.rs-online.com/webd...6b8002b71e.pdf

It would be much more challenging with a halogen light where there is a
significant inrush current when the filament is cold. An electric fire
is a relatively benign load with a decently high cold resistance.

Nominally 13A fuses will support boiling two 3kW kettles for long enough
to destroy the still coiled up extension cable they were plugged into.

All our village hall extension cables now have thermal overload
protection to save them from the church's tea ladies.

--
Regards,
Martin Brown

In article ,
whisky-dave wrote:

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric
fire at a potential difference of 240v

If you're talking a plug fuse, the load is irrelevant. As it is to protect
the flex etc. In other words, a table light with a 20 watt bulb would be
fine with a 13 amp fuse if the cable was rated at 13 amps.

--
*The closest I ever got to a 4.0 in school was my blood alcohol content*

Dave Plowman London SW
To e-mail, change noise into sound.

In message
Martin Brown wrote:

On 19/03/2018 16:15, Harry Bloomfield wrote:
whisky-dave pretended :
Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric
fire at a potential difference of 240v

5amp ought to cover it, but it is very tight. If it fails find a 10amp.

It isn't *all* that tight in practice but the plug will run slightly
warm. A nominal 5A fuse will take nearly 20A to blow in the first second
and will probably support a current of 7A almost indefinitely. eg.

https://docs-emea.rs-online.com/webd...6b8002b71e.pdf

It would be much more challenging with a halogen light where there is a
significant inrush current when the filament is cold. An electric fire
is a relatively benign load with a decently high cold resistance.

Nominally 13A fuses will support boiling two 3kW kettles for long enough
to destroy the still coiled up extension cable they were plugged into.

This is due to induction heating not resistive heating by the load
supplied.

All our village hall extension cables now have thermal overload
protection to save them from the church's tea ladies.



--
John Bryan

On 19/03/2018 16:53, Dave Plowman (News) wrote:
In article ,
whisky-dave wrote:

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric
fire at a potential difference of 240v

If you're talking a plug fuse, the load is irrelevant. As it is to protect
the flex etc. In other words, a table light with a 20 watt bulb would be
fine with a 13 amp fuse if the cable was rated at 13 amps.


Won't all fuses less than 13a protect the cable then!

On 19/03/18 15:27, whisky-dave wrote:

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric fire at a potential difference of 240v

well you could TRY a 5A. But my guess is that its pushing the limits.
13A. Remember the fuse is to protect the wiring that is downstream of
it only.




--
New Socialism consists essentially in being seen to have your heart in
the right place whilst your head is in the clouds and your hand is in
someone else's pocket.

whisky-dave wrote:

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric fire
at a potential difference of 240v

10A . But 13A is fine.
--

Roger Hayter

On 19/03/2018 16:18, whisky-dave wrote:
On Monday, 19 March 2018 16:11:42 UTC, The Other Mike wrote:
On Mon, 19 Mar 2018 08:27:31 -0700 (PDT), whisky-dave
wrote:

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric fire at a potential difference of 240v

Assuming you mean at the BS1363 plug then the fuse should be sized to protect
the cable.
--

Nice, that's the sort of answer I'd expect :-)

But this was a question given to students doing our science foundation course where they are expected to say 5 Amps. (a student has left their marked paper (mid semester test) in the lab so I thought I'd have a look).

I have also been told that H&S state that consumers/users should only use either a 3A of 13 amp fuse in a plug and that is what we as technicians have been told to use, even though I have loads of fuses including 1A, 2A, 5A, 7A, 10A and 13A


https://www.rospa.com/home-safety/uk...hoosing-fuses/



I think some of that might be down to BS7671 only mentioning 3A and 13A
fuses. Although I cannot find a reference to that ATM.

--
Adam

On Monday, 19 March 2018 16:18:39 UTC, whisky-dave wrote:
On Monday, 19 March 2018 16:11:42 UTC, The Other Mike wrote:
On Mon, 19 Mar 2018 08:27:31 -0700 (PDT), whisky-dave
wrote:

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric fire at a potential difference of 240v

Assuming you mean at the BS1363 plug then the fuse should be sized to protect
the cable.
--

Nice, that's the sort of answer I'd expect :-)

But this was a question given to students doing our science foundation course where they are expected to say 5 Amps. (a student has left their marked paper (mid semester test) in the lab so I thought I'd have a look).

5A is a better answer than 13. It would give added protection against a partial short of the heating element. Either is compliant with BS. TBH this is very basic stuff.

I have also been told that H&S state that consumers/users should only use either a 3A of 13 amp fuse in a plug and that is what we as technicians have been told to use, even though I have loads of fuses including 1A, 2A, 5A, 7A, 10A and 13A

complete cobblers of course.

https://www.rospa.com/home-safety/uk...hoosing-fuses/

a useful rule of thumb for folks that need to be told which fuse because they have no idea. Such people normally only have 3 & 13A. That's all it is.


NT

On Monday, 19 March 2018 17:59:10 UTC, Sam wrote:
On 19/03/2018 16:53, Dave Plowman (News) wrote:
In article ,
whisky-dave wrote:

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric
fire at a potential difference of 240v

If you're talking a plug fuse, the load is irrelevant. As it is to protect
the flex etc. In other words, a table light with a 20 watt bulb would be
fine with a 13 amp fuse if the cable was rated at 13 amps.


Won't all fuses less than 13a protect the cable then!

No, for 4 reasons.

1. Some appliances have old thin cables that come nowhere near being protected by a 10A fuse.
2. Some old appliances need low current mains fuses to give them basic safety protection.
3. Some new appliances have noncompliant CCS cables.
3. Some 13A fuses are in reality 13A or greater. This applies both to old pre-ASTM and new counterfeit fuses.


NT

On Monday, 19 March 2018 18:28:56 UTC, The Natural Philosopher wrote:
On 19/03/18 15:27, whisky-dave wrote:

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric fire at a potential difference of 240v

well you could TRY a 5A. But my guess is that its pushing the limits.

it's not, any more than a 13A load is pushing it with a 13A fuse. It's precisely what they're designed for.

13A. Remember the fuse is to protect the wiring that is downstream of
it only.

that garbage is much trotted out.


NT

On Monday, 19 March 2018 19:25:17 UTC, John Bryan wrote:
In message
Martin Brown wrote:
On 19/03/2018 16:15, Harry Bloomfield wrote:
whisky-dave pretended :

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric
fire at a potential difference of 240v

5amp ought to cover it, but it is very tight. If it fails find a 10amp.

It isn't *all* that tight in practice but the plug will run slightly
warm. A nominal 5A fuse will take nearly 20A to blow in the first second
and will probably support a current of 7A almost indefinitely. eg.

https://docs-emea.rs-online.com/webd...6b8002b71e.pdf

It would be much more challenging with a halogen light where there is a
significant inrush current when the filament is cold. An electric fire
is a relatively benign load with a decently high cold resistance.

Nominally 13A fuses will support boiling two 3kW kettles for long enough
to destroy the still coiled up extension cable they were plugged into.

This is due to induction heating not resistive heating by the load
supplied.

Since current is the same but opposite direction in L&N conductors there is no significant induction heating.


NT

wrote:

On Monday, 19 March 2018 16:18:39 UTC, whisky-dave wrote:
On Monday, 19 March 2018 16:11:42 UTC, The Other Mike wrote:
On Mon, 19 Mar 2018 08:27:31 -0700 (PDT), whisky-dave
wrote:

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric
fire at a potential difference of 240v

Assuming you mean at the BS1363 plug then the fuse should be sized to
protect
the cable.
--

Nice, that's the sort of answer I'd expect :-)

But this was a question given to students doing our science foundation
course where they are expected to say 5 Amps. (a student has left their
marked paper (mid semester test) in the lab so I thought I'd have a
look).

5A is a better answer than 13. It would give added protection against a
partial short of the heating element. Either is compliant with BS. TBH
this is very basic stuff.

It depends on the heating elements temperature coefficient of
resistivity and how hot it gets. Some 1.15kW heaters may draw much
more than 5A for tens of seconds on starting.



I have also been told that H&S state that consumers/users should only
use either a 3A of 13 amp fuse in a plug and that is what we as
technicians have been told to use, even though I have loads of fuses
including 1A, 2A, 5A, 7A, 10A and 13A

complete cobblers of course.


https://www.rospa.com/home-safety/uk...icity/plugs-fu
ses/choosing-fuses/

a useful rule of thumb for folks that need to be told which fuse because
they have no idea. Such people normally only have 3 & 13A. That's all it
is.


NT


--

Roger Hayter

John Bryan wrote:

In message
Martin Brown wrote:

On 19/03/2018 16:15, Harry Bloomfield wrote:
whisky-dave pretended :
Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric
fire at a potential difference of 240v

5amp ought to cover it, but it is very tight. If it fails find a 10amp.

It isn't *all* that tight in practice but the plug will run slightly
warm. A nominal 5A fuse will take nearly 20A to blow in the first second
and will probably support a current of 7A almost indefinitely. eg.

https://docs-emea.rs-online.com/webd...6b8002b71e.pdf

It would be much more challenging with a halogen light where there is a
significant inrush current when the filament is cold. An electric fire
is a relatively benign load with a decently high cold resistance.

Nominally 13A fuses will support boiling two 3kW kettles for long enough
to destroy the still coiled up extension cable they were plugged into.

This is due to induction heating not resistive heating by the load
supplied.

No it is due to resistive heating and poor heat dissipation by the
coiled lead.



All our village hall extension cables now have thermal overload
protection to save them from the church's tea ladies.


--

Roger Hayter

On 19/03/2018 19:28, wrote:
On Monday, 19 March 2018 16:18:39 UTC, whisky-dave wrote:
On Monday, 19 March 2018 16:11:42 UTC, The Other Mike wrote:
On Mon, 19 Mar 2018 08:27:31 -0700 (PDT), whisky-dave
wrote:

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric fire at a potential difference of 240v

Assuming you mean at the BS1363 plug then the fuse should be sized to protect
the cable.
--

Nice, that's the sort of answer I'd expect :-)



Does the BS require that the heating element should burn out before the
cable does (say there's a voltage surge)?

And does the BS require that the element will burn out safely without
setting fire to something?

on 19/03/2018, John Bryan supposed :
This is due to induction heating not resistive heating by the load
supplied.

Rubbish, there will be no inductive heating effect. The current in live
will match that in neutral and thus negate any induction. The only
heating effect in a coiled lead on ac is that of resistive heating,
which becomes a problem on a coiled up lead, because the heat produced
is unable to escape.

On 19/03/2018 19:55, Harry Bloomfield wrote:
on 19/03/2018, John Bryan supposed :
This is due to induction heating not resistive heating by the load
supplied.

Rubbish, there will be no inductive heating effect. The current in live
will match that in neutral and thus negate any induction. The only
heating effect in a coiled lead on ac is that of resistive heating,
which becomes a problem on a coiled up lead, because the heat produced
is unable to escape.

Could not have put it better!

On 19/03/2018 19:48, GB wrote:
On 19/03/2018 19:28, wrote:
On Monday, 19 March 2018 16:18:39 UTC, whisky-daveÂ* wrote:
On Monday, 19 March 2018 16:11:42 UTC, The Other MikeÂ* wrote:
On Mon, 19 Mar 2018 08:27:31 -0700 (PDT), whisky-dave

wrote:

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW
electric fire at a potential difference of 240v

Assuming you mean at the BS1363 plug then the fuse should be sized
to protect
the cable.
--

Nice, that's the sort of answer I'd expect :-)



Does the BS require that the heating element should burn out before the
cable does (say there's a voltage surge)?

And does the BS require that the element will burn out safely without
setting fire to something?


I don't think that BS761 has an opinion on it. Overload is not relevant
(the load is set by the heaters wattage) so in this case only fault
current applies.

If you have such a voltage surge then the least of your worries would be
a 1.15kW heater!

--
Adam

John Bryan wrote:
All our village hall extension cables now have thermal overload
protection to save them from the church's tea ladies.

Hmm, a strict reading of the rules would suggest that your electrical
installation is defective - not fit for purpose as you should have
sockets available where the kettles need to go, rather than using
extension leads. Of course, how to provide sockets in the middle of the
floor for kettles which don't then become a trip hazard when the same
area is used as a dance floor is an interesting challenge...


Mike

In article ,
writes:
On Monday, 19 March 2018 16:18:39 UTC, whisky-dave wrote:
On Monday, 19 March 2018 16:11:42 UTC, The Other Mike wrote:
On Mon, 19 Mar 2018 08:27:31 -0700 (PDT), whisky-dave
wrote:

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric fire at a potential difference of 240v

Assuming you mean at the BS1363 plug then the fuse should be sized to protect
the cable.

Nice, that's the sort of answer I'd expect :-)

But this was a question given to students doing our science foundation course where they are expected to say 5 Amps. (a student has left their marked paper (mid semester test) in the lab so I thought I'd have a look).

5A is a better answer than 13. It would give added protection against a partial short of the heating element. Either is compliant with BS. TBH this is very basic stuff.

A 5A fuse passing 4A will give off 0.64W, generating some heating
and deterioration of the plug over time.

A 13A fuse passing 4A will give off 0.09W, resulting in less heating
in the plug and longer life.

Unless the heater has a longer flex than is allowed by EU regulations
(which requires the flex is protected against fault current when fused
at 16A), a 13A fuse will protect the cable OK.

(A BS1362 fuse gives off about 1W at full load current.)

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On Monday, 19 March 2018 19:39:09 UTC, Roger Hayter wrote:
tabbypurr wrote:
On Monday, 19 March 2018 16:18:39 UTC, whisky-dave wrote:
On Monday, 19 March 2018 16:11:42 UTC, The Other Mike wrote:
On Mon, 19 Mar 2018 08:27:31 -0700 (PDT), whisky-dave
wrote:

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric
fire at a potential difference of 240v

Assuming you mean at the BS1363 plug then the fuse should be sized to
protect
the cable.
--

Nice, that's the sort of answer I'd expect :-)

But this was a question given to students doing our science foundation
course where they are expected to say 5 Amps. (a student has left their
marked paper (mid semester test) in the lab so I thought I'd have a
look).

5A is a better answer than 13. It would give added protection against a
partial short of the heating element. Either is compliant with BS. TBH
this is very basic stuff.

It depends on the heating elements temperature coefficient of
resistivity and how hot it gets. Some 1.15kW heaters may draw much
more than 5A for tens of seconds on starting.

a) which ones?
b) fuses are pretty tolerant of that. Look up the curves.


NT

On Mon, 19 Mar 2018 19:55:23 +0000, Harry Bloomfield wrote:

on 19/03/2018, John Bryan supposed :
This is due to induction heating not resistive heating by the load
supplied.

Rubbish, there will be no inductive heating effect. The current in live
will match that in neutral and thus negate any induction. The only
heating effect in a coiled lead on ac is that of resistive heating,
which becomes a problem on a coiled up lead, because the heat produced
is unable to escape.

+1

Nicely put. That saved me having to stick *my* oar in. :-)

--
Johnny B Good

On Mon, 19 Mar 2018 17:59:03 +0000, Sam wrote:

On 19/03/2018 16:53, Dave Plowman (News) wrote:
In article ,
whisky-dave wrote:

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric
fire at a potential difference of 240v

If you're talking a plug fuse, the load is irrelevant. As it is to
protect the flex etc. In other words, a table light with a 20 watt bulb
would be fine with a 13 amp fuse if the cable was rated at 13 amps.


Won't all fuses less than 13a protect the cable then!

Yes. Provided the load doesn't demand the use of a higher fuse rating,
the lower the better the protection. The only issue would that of the
heating effect inside the plug when running close to the chosen fuse
rating current limit[1]. With a table lamp, even a 1A fuse will be safe
from this unless you fit a 250W GLS lamp (in which case, choose a 2 or 3
amp fuse. :-).

[1] All fuses rely upon the heating effect to perform their function so
the plug's fuse holder must be designed to cope with the circa 1 to 2
watt's worth of dissipation whenever the fuse is carrying its rated
current. The lower the fuse rating, the lower the dissipation at the
rated current. However, this isn't a linear variation since the thicker
fuse wire inside a 13A fuse cartridge will conduct the heat away more
rapidly via its end caps into the Live pin and the live wire termination
than the thinner wire in a 1A fuse cartridge.

--
Johnny B Good

On 19/03/2018 15:27, whisky-dave wrote:

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric fire at a potential difference of 240v


13A.

Bill

On 19/03/2018 21:34, Mike Humphrey wrote:
John Bryan wrote:
All our village hall extension cables now have thermal overload
protection to save them from the church's tea ladies.

Hmm, a strict reading of the rules would suggest that your electrical
installation is defective - not fit for purpose as you should have
sockets available where the kettles need to go, rather than using

There is power where the kettles should go, but the tea ladies sometimes
do strange things to avoid walking about 3m to the kitchen bench. The
extension was coiled up and being used essentially as a 2 way adaptor so
they could plug in multiple kettles at once on a nearby table instead.

extension leads. Of course, how to provide sockets in the middle of the
floor for kettles which don't then become a trip hazard when the same
area is used as a dance floor is an interesting challenge...

I have concluded that you have to assume that people will do crazy
things and defend against them. Rules only go so far and get ignored.

--
Regards,
Martin Brown

On Mon, 19 Mar 2018 12:31:42 -0700 (PDT), wrote:

On Monday, 19 March 2018 17:59:10 UTC, Sam wrote:
On 19/03/2018 16:53, Dave Plowman (News) wrote:
In article ,
whisky-dave wrote:

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric
fire at a potential difference of 240v

If you're talking a plug fuse, the load is irrelevant. As it is to protect
the flex etc. In other words, a table light with a 20 watt bulb would be
fine with a 13 amp fuse if the cable was rated at 13 amps.


Won't all fuses less than 13a protect the cable then!

No, for 4 reasons.

1. Some appliances have old thin cables that come nowhere near being protected by a 10A fuse.
2. Some old appliances need low current mains fuses to give them basic safety protection.
3. Some new appliances have noncompliant CCS cables.
3. Some 13A fuses are in reality 13A or greater. This applies both to old pre-ASTM and new counterfeit fuses.

NT

With the v. few items with old, thin flex I have fuses of 1, 2, 3, 5, 7, 10
& 13A semi-sorted in 3 boxen. I suppose, with a bit of modding, I could also
look at sub-1A fuses (fast, delay, slow), but nowadays they're pretty well
redundant.
We had an oven at work that drew about 15 - 16A peak but with odd solenoids
banging in at times. The v. old 13A fuse went and the replacements would
last only days - not good in military testing.
Had to hard-wire it to a 20A fused breaker in the end.
--
Peter.
The gods will stay away
whilst religions hold sway

Unless there is a surge on start up which can happen on heaters.
I'm very surprised we do not get 7.5 amp fuses for this sort of thing. 13
amp ones go with a heck of a bang. You can get very slow blow fuses of
course with a lot of that heat conducting stuff in them, but I'd guess a
lot of fuses one sees in pound shops are dodgy in the extreme.
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"Graham." wrote in message
...

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric fire
at a potential difference of 240v
1150/240=4.79 so theoretically a 5A fuse shoud do.
--

Graham.
%Profound_observation%

Yes most people who set questions in exams have not experienced the real
world very much has been my suspicion for a while now. They are steeped in
the maths but know little about the real world.
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"Bill Wright" wrote in message
news
On 19/03/2018 15:27, whisky-dave wrote:

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric fire
at a potential difference of 240v


13A.

Bill

In article ,
Johnny B Good wrote:
Something less trivial than a 60W table lamp such as a mains powered
radio or TV set will have its own safety fuse built in to protect
against the risk of conflagration,

And that is the correct way to protect the appliance if needed. Not using
the plug fuse.

In the appliance you can choose the most suitable type of fuse. Fast blow,
anti-surge, etc.

Hence there not being the same range of plug fuses as once was the case.
Most won't understand the differences. So best to make things for a single
one.

--
*What happens if you get scared half to death twice? *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Martin Brown wrote:
There is power where the kettles should go, but the tea ladies sometimes
do strange things to avoid walking about 3m to the kitchen bench. The
extension was coiled up and being used essentially as a 2 way adaptor so
they could plug in multiple kettles at once on a nearby table instead.

I'd say you shouldn't make such an extension available in a public place.
Use single outlet ones only. And not cable reels as they tend not to get
fully unwound.

--
*The sooner you fall behind, the more time you'll have to catch up *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Brian Gaff wrote:
Yes most people who set questions in exams have not experienced the real
world very much has been my suspicion for a while now. They are steeped in
the maths but know little about the real world.

It is the real world which says no new appliance should require a less
than 13 amp fuse in a plug. Because if a lower value blows, many will just
replace it with what is to hand, so likely a 13 amp one.

--
*Change is inevitable, except from a vending machine*

Dave Plowman London SW
To e-mail, change noise into sound.

On Monday, 19 March 2018 17:02:42 UTC, Dave Plowman (News) wrote:
In article ,
whisky-dave wrote:

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric
fire at a potential difference of 240v

If you're talking a plug fuse, the load is irrelevant. As it is to protect
the flex etc. In other words, a table light with a 20 watt bulb would be
fine with a 13 amp fuse if the cable was rated at 13 amps.

But that wasn't the question was it.
This was a mid-term test, so you would got this question wrong.

On Monday, 19 March 2018 18:38:42 UTC, Roger Hayter wrote:
whisky-dave wrote:

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric fire
at a potential difference of 240v

10A . But 13A is fine.

So we both got it wrong then because the answer is 5A.

On Monday, 19 March 2018 19:28:09 UTC, wrote:
On Monday, 19 March 2018 16:18:39 UTC, whisky-dave wrote:
On Monday, 19 March 2018 16:11:42 UTC, The Other Mike wrote:
On Mon, 19 Mar 2018 08:27:31 -0700 (PDT), whisky-dave
wrote:

Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric fire at a potential difference of 240v

Assuming you mean at the BS1363 plug then the fuse should be sized to protect
the cable.
--

Nice, that's the sort of answer I'd expect :-)

But this was a question given to students doing our science foundation course where they are expected to say 5 Amps. (a student has left their marked paper (mid semester test) in the lab so I thought I'd have a look).

5A is a better answer than 13. It would give added protection against a partial short of the heating element. Either is compliant with BS. TBH this is very basic stuff.

Which is why it's a question in the science foundation course I supose.


I have also been told that H&S state that consumers/users should only use either a 3A of 13 amp fuse in a plug and that is what we as technicians have been told to use, even though I have loads of fuses including 1A, 2A, 5A, 7A, 10A and 13A

complete cobblers of course.

https://www.rospa.com/home-safety/uk...hoosing-fuses/

a useful rule of thumb for folks that need to be told which fuse because they have no idea. Such people normally only have 3 & 13A. That's all it is.

The same fuses our PAT tester person uses then.

So it really depends on your job then and little to do with the applienace ?
So as I would think not a very good quetion to ask.

On Mon, 19 Mar 2018 12:33:03 -0700 (PDT), wrote:

On Monday, 19 March 2018 18:28:56 UTC, The Natural Philosopher wrote:


13A. Remember the fuse is to protect the wiring that is downstream of
it only.

that garbage is much trotted out.


With a BS1363 plug top to IEC 60320 C13 connector with both the cable (BS EN
50525 sized at 1mm^2) and the end connector rated at 10A which fuse would be
fitted by the manufacturer?

With a BS1363 plug top to IEC 60320 C13 connector with the cable BS EN 50525
sized at 0.75mm^2) rated at 5A and the end connector rated at 10A which fuse
would be fitted by the manufacturer?

The limit of supply by the manufacturer in both cases is the BS1363 plug top
with a BS1362 fuse, the cable to BS EN 50525 and the IEC 60320 C13 connector as
a tested and complete assembly to be offered for sale in the UK.

--

On Tuesday, 20 March 2018 09:24:58 UTC, Brian Gaff wrote:
Yes most people who set questions in exams have not experienced the real
world very much has been my suspicion for a while now. They are steeped in
the maths but know little about the real world.
Brian

He is an Associate Lecturer late 60s early 70s.