House of Horrors

In article , charles
writes
Have you ever come across an "unfused adaptor"?

I have quite a few mains adapters which do not have fuses in them, what
would be the point? There is no cable to protect, it is an extension of
the wall socket it is plugged in to, and if a fault caused the adapter
fuse to blow it would cause the other items plugged in to it to stop
operating.

--
Ian G8ILZ
There are always two people in every pictu the photographer and the viewer.
~Ansel Adams

In article ,
Prometheus wrote:
In article , charles
writes
Have you ever come across an "unfused adaptor"?

I have quite a few mains adapters which do not have fuses in them, what
would be the point? There is no cable to protect, it is an extension of
the wall socket it is plugged in to, and if a fault caused the adapter
fuse to blow it would cause the other items plugged in to it to stop
operating.

but an unfused adaptor could mean you were drawing a full 32 amps through a
single socket with all the overheating problems at the wall socket that
would ensue.

--
From KT24 - in "Leafy Surrey"

Using a RISC OS computer running v5.11

"John Rumm" wrote in message
...
Bill Wright wrote:

What's the thing about the rating of a fuse versus the actual current
needed to blow it immediately? There's some sort of standard about this I
believe.

One of the things that surprises many is just how much current is required
to blow a fuse. If you take the example of a rewireable 5A fuse of the
type you find in older consumer units (aka fusebox), you can see from:

http://www.internode.co.uk/temp/fuse.pdf

That it will carry 9A indefinitely, it takes 13A to get it to blow in five
seconds, or 45A to get it to go "instantly" (i.e. 0.1 sec or less)


This seems as goo a time as ever to post these two pictures

http://myweb.tiscali.co.uk/infoweb/fusebox.jpg
http://myweb.tiscali.co.uk/infoweb/fusebox2.jpg

I took them a couple of months ago in the back of a Chemists
shop where I was working (not on the electrics).

Yes it is live and in use.

What got me was the sheet in the lid which rather suggests that
a 12SWG "nail" would be OK if you needed 150A

--
Graham.
%Profound_observation%

"Owain" wrote in message

charles wrote:
but an unfused adaptor could mean you were drawing a full 32 amps
through a single socket with all the overheating problems at the
wall socket that would ensue.

That would mean having about 7kW of electric fire at one location
though, which is very unlikely to happen.

You might have a double boiling ring and an oven at the same point in a
bedsitter now they don't make Baby Bellings.

--
Max Demian

"Prometheus" wrote in message
...
In article , Bill Wright As I recall
there is, or was, a difference between British and USA specifications. A
USA fuse should blow at the rated current (limit value), I am not sure
about how quickly, and time delay fuses would obviously have a delay to
allow a brief over current. British fuses should blow at 1.7 times the
rated current and pass the rated current indefinitely (operating value,
think of a 3kW fire with a 13A fuse). Obviously there are time and ageing
factors again. This difference could make repairing USA manufactured
equipment in the UK problematic.

Ah! Interesting! Thanks!

Bill

"Peter Hayes" wrote in message
m...
Max Demian wrote:
I've never seen an unfused adaptor. They'd almost certainly be illegal
to sell.

CPC were selling them not so long ago; propbably still are. They were 50p
each.

Bill

In article ,
Bill Wright wrote:

"Peter Hayes" wrote in message
m...
Max Demian wrote:
I've never seen an unfused adaptor. They'd almost certainly be illegal
to sell.

CPC were selling them not so long ago; propbably still are. They were 50p
each.

Now 82p + vat.

--
From KT24 - in "Leafy Surrey"

Using a RISC OS computer running v5.11

"Owain" wrote in message

Max Demian wrote:
but an unfused adaptor could mean you were drawing a full 32 amps
through a single socket with all the overheating problems at the
wall socket that would ensue.
That would mean having about 7kW of electric fire at one location
though, which is very unlikely to happen.
You might have a double boiling ring and an oven at the same point
in a bedsitter now they don't make Baby Bellings.

You might, but it would be contrary to the wiring regs, because a
fixed cooker point should be provided in such a scenario.

Only for "proper" cookers.

(And mini
cookers not dissimilar to Baby Bellings are available from Argos.)

The separate ovens and hotplate units would come with fitted 13A plugs.

Even so, the boiling rings and oven would be on thermostats with a
duty cycle, very unlikely to be drawing 2x13A simultaneously for any
length of time.

Might do if you are cooking full blast.

32A ring circuits are designed for 'general purposes' not permanent
heating or cooking loads

The Baby Bellings were available in two versions - one had an
interlock so both rings and grill couldn't be used at the same time, and
was for
13A sockets, another version without the interlock was for cooker
circuits.

Don't forget the "original"ones with a solid hot plate on the top, and an
oven below. They didn't have any interlock (though they might have been made
for a 15A socket).

--
Max Demian

Max Demian wrote:

Even so, the boiling rings and oven would be on thermostats with a
duty cycle, very unlikely to be drawing 2x13A simultaneously for any
length of time.

Might do if you are cooking full blast.

Unlikely even then. The wiring regs allow you to apply the concept of
diversity to cookers when assessing their load, and designing circuits
to feed them in a domestic premises. This takes 10A of the load plus 30%
of the remainder as a realistic maximum figure.

So a 26A cooker, would be assessed as 10 + 20% of 16 or 14.8A


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

"Max Demian" wrote in message
...
"Owain" wrote in message
The Baby Bellings were available in two versions - one had an
interlock so both rings and grill couldn't be used at the same time, and
was for
13A sockets, another version without the interlock was for cooker
circuits.

Some large appliances have two mains leads and two 13A plugs, so the load
can be shared between circuits. Examples are dehumidifiers and those things
that caterers use to keep all the food hot as they serve it. Of course these
things would be better using 3 phase but usually there's only 240 available
so they're designed for two 240 supplies.

Bill