Not being electrically savvy but should the `trip` switch on the mains
meter not have clicked in and cut the current off to prevent a fir starting.

On Friday, 23 June 2017 19:21:28 UTC+1, ss wrote:
Not being electrically savvy but should the `trip` switch on the mains
meter not have clicked in and cut the current off to prevent a fir starting.

Depends on the details of the fridge fault. MCBs certainly don't eliminate all fires.


NT

On 23/06/2017 19:37, wrote:
On Friday, 23 June 2017 19:21:28 UTC+1, ss wrote:
Not being electrically savvy but should the `trip` switch on the mains
meter not have clicked in and cut the current off to prevent a fir starting.

Depends on the details of the fridge fault. MCBs certainly don't eliminate all fires.


NT


I blame 'frost-free' fridge freezers. This involves heating elements
in close contact with plastic and nasty insulation, and
circuit boards with microprocssors that then need a low voltage
dc supply from the mains, which means additional gubbins that
can overheat.

My Liebherr fridge freezer has a bog standard electro-mechanical
thstat with wax inside it and the microswitches are enclosed
inside a fairly tough metal box.

On 23/06/17 19:21, ss wrote:
Not being electrically savvy but should the `trip` switch on the mains
meter not have clicked in and cut the current off to prevent a fir
starting.

What trip switch?

"Tim Watts" wrote in message
...
On 23/06/17 19:21, ss wrote:
Not being electrically savvy but should the `trip` switch on the mains
meter not have clicked in and cut the current off to prevent a fir
starting.

What trip switch?

The over-current or earth leakage trip-switches in the "fuse box". Or in
extreme case the 60 A "company fuse" (which i think is always still an
old-fashioned melting-metal fuse). But I think you *did* know that.

The difficulty is when the short is not to earth and is a lower-than-normal
resistance but not a complete short, so you draw a larger current (or a
current through the wrong material, allowing it to heat up) but not a
current that is large enough to blow/trip the cutout.

On 23/06/17 20:05, NY wrote:
"Tim Watts" wrote in message
...
On 23/06/17 19:21, ss wrote:

What trip switch?

The over-current or earth leakage trip-switches in the "fuse box". Or in
extreme case the 60 A "company fuse" (which i think is always still an
old-fashioned melting-metal fuse). But I think you *did* know that.

The difficulty is when the short is not to earth and is a
lower-than-normal resistance but not a complete short, so you draw a
larger current (or a current through the wrong material, allowing it to
heat up) but not a current that is large enough to blow/trip the cutout.

It sounded to me like the PP thought there was some magic fire detecting
device...

Back to the point, the fuse in the fridge's plug would be the first to
go, unless there was an RCD *and* the appliance is a Class I (earthed)
device (which seems likely for a metal fridge).

But it's possible to start a fire with no serious overload - with the
right conditions, an amp at 230V can make things extremely hot - and if
the hot thing is next to a combustible thing...

On Friday, 23 June 2017 20:36:46 UTC+1, Tim Watts wrote:
On 23/06/17 20:05, NY wrote:
"Tim Watts" wrote in message
...
On 23/06/17 19:21, ss wrote:

What trip switch?

The over-current or earth leakage trip-switches in the "fuse box". Or in
extreme case the 60 A "company fuse" (which i think is always still an
old-fashioned melting-metal fuse). But I think you *did* know that.

The difficulty is when the short is not to earth and is a
lower-than-normal resistance but not a complete short, so you draw a
larger current (or a current through the wrong material, allowing it to
heat up) but not a current that is large enough to blow/trip the cutout.

It sounded to me like the PP thought there was some magic fire detecting
device...

Back to the point, the fuse in the fridge's plug would be the first to
go, unless there was an RCD *and* the appliance is a Class I (earthed)
device (which seems likely for a metal fridge).

But it's possible to start a fire with no serious overload - with the
right conditions, an amp at 230V can make things extremely hot - and if
the hot thing is next to a combustible thing...

The bimetal cutout on the fridge compressor, the plug fuse, the MCB, the RCD, the supplier's fuse and if present (very unlikely) an AFCI are all fire preventing devices. All of them only work on a percentage of fire causing faults.


NT

On Fri, 23 Jun 2017 16:02:56 -0700 (PDT), wrote:

On Friday, 23 June 2017 20:36:46 UTC+1, Tim Watts wrote:
On 23/06/17 20:05, NY wrote:
"Tim Watts" wrote in message
...
On 23/06/17 19:21, ss wrote:

What trip switch?

The over-current or earth leakage trip-switches in the "fuse box". Or in
extreme case the 60 A "company fuse" (which i think is always still an
old-fashioned melting-metal fuse). But I think you *did* know that.

The difficulty is when the short is not to earth and is a
lower-than-normal resistance but not a complete short, so you draw a
larger current (or a current through the wrong material, allowing it to
heat up) but not a current that is large enough to blow/trip the cutout.

It sounded to me like the PP thought there was some magic fire detecting
device...

Back to the point, the fuse in the fridge's plug would be the first to
go, unless there was an RCD *and* the appliance is a Class I (earthed)
device (which seems likely for a metal fridge).

But it's possible to start a fire with no serious overload - with the
right conditions, an amp at 230V can make things extremely hot - and if
the hot thing is next to a combustible thing...

The bimetal cutout on the fridge compressor, the plug fuse, the MCB, the RCD, the supplier's fuse and if present (very unlikely) an AFCI are all fire preventing devices. All of them only work on a percentage of fire causing faults.


NT

I've never seen an AFCI, I see they are now common in the USA and that
they are prone to false tripping.


--

Graham.
%Profound_observation%

On 23/06/2017 20:05, NY wrote:
"Tim Watts" wrote in message
...
On 23/06/17 19:21, ss wrote:
Not being electrically savvy but should the `trip` switch on the
mains meter not have clicked in and cut the current off to prevent a
fir starting.

What trip switch?

The over-current or earth leakage trip-switches in the "fuse box". Or in
extreme case the 60 A "company fuse" (which i think is always still an
old-fashioned melting-metal fuse). But I think you *did* know that.

ELCB may potentially save you if the cable chars or melts sufficiently
to allow a live to earth current that trips it out. But if you are out
of luck the leak goes live to neutral and a nominal 13A fuse will
support something like 20A for a few minutes...

Seen that happen with internally molten overloaded extension leads that
haven't been unwound properly. All the ones in out village hall now have
thermal cutouts to defend against potential abuse.

The difficulty is when the short is not to earth and is a
lower-than-normal resistance but not a complete short, so you draw a
larger current (or a current through the wrong material, allowing it to
heat up) but not a current that is large enough to blow/trip the cutout.

It is particularly bad in those tall floor fan heaters that swivel from
side to side with a 13A fuse and a cable that is forever being twisted
to and fro when the thing is in use and allowed to move as designed.

It isn't really a case of if it fails so much as when...

--
Regards,
Martin Brown

ss wrote

Not being electrically savvy but should the `trip` switch on the mains
meter not have clicked in and cut the current off to prevent a fir
starting.

Its not always possible for the trip in the cu to prevent a fire.

For example, if the butane like refrigerant in the fridge starts
to leak out due to a seal or weld failure and that is ignited
by something as simple as a relay tripping normally to start
the motor because its not cold enough, no cu trip is going
to even notice any electrical problem until the fire melts
wires and produces a short that way, by which time the
fire is well alight and it doesnt matter if the mains is
disconnected, the fire will keep burning.

On 23/06/2017 19:21, ss wrote:

Not being electrically savvy but should the `trip` switch on the mains
meter not have clicked in and cut the current off to prevent a fir
starting.

Not necessarily - it depends on if the fault caused it to draw too much
current or allow excess earth leakage. If the answer to both those is
"no", then the circuit protection will be none the wiser that things are
going pear shaped elsewhere.


--
Cheers,

John.

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

On 23/06/17 21:15, John Rumm wrote:
On 23/06/2017 19:21, ss wrote:

Not being electrically savvy but should the `trip` switch on the mains
meter not have clicked in and cut the current off to prevent a fir
starting.

Not necessarily - it depends on if the fault caused it to draw too much
current or allow excess earth leakage. If the answer to both those is
"no", then the circuit protection will be none the wiser that things are
going pear shaped elsewhere.



While, assuming there was an RCD on the circuit, it is hard to believe
once the fire 'took hold', the insulation wouldn't cause it to trip, the
fire could easily continue to burn.

The real question is, why the occupier/owner didn't take steps to
contain the fire and call the fire brigade. Early reports indicate he
collected items and told a neighbour, who could see the fire in his
kitchen- meaning the door to his flat was open. Had the precaution of
simply closing doors and windows etc. and ensuring the fire service were
called, could the fire have been contained?

Those being evacuated in Camden reported that there had been several
fires in their block(s), all of which had been contained.

This isn't an attempt to blame the tenant, he may well have simply
panicked or not known what to do for whatever reason. Sadly, such things
happen.

"Brian Reay" wrote in message
news
On 23/06/17 21:15, John Rumm wrote:
On 23/06/2017 19:21, ss wrote:

Not being electrically savvy but should the `trip` switch on the mains
meter not have clicked in and cut the current off to prevent a fir
starting.

Not necessarily - it depends on if the fault caused it to draw too much
current or allow excess earth leakage. If the answer to both those is
"no", then the circuit protection will be none the wiser that things are
going pear shaped elsewhere.



While, assuming there was an RCD on the circuit, it is hard to believe
once the fire 'took hold', the insulation wouldn't cause it to trip, the
fire could easily continue to burn.

The real question is, why the occupier/owner didn't take steps to contain
the fire and call the fire brigade. Early reports indicate he collected
items and told a neighbour, who could see the fire in his kitchen- meaning
the door to his flat was open. Had the precaution of simply closing doors
and windows etc. and ensuring the fire service were called, could the fire
have been contained?

Those being evacuated in Camden reported that there had been several fires
in their block(s), all of which had been contained.

This isn't an attempt to blame the tenant, he may well have simply
panicked or not known what to do for whatever reason. Sadly, such things
happen.

when the transformer went in my TS520SE the amount of smoke was unbelievable
but I managed to cut the power before the house RCD tripped .......

On Sat, 24 Jun 2017 14:28:27 +0100
"Jim GM4DHJ ..." wrote:

when the transformer went in my TS520SE

Your what?

--
Davey.

"Davey" wrote in message
news
On Sat, 24 Jun 2017 14:28:27 +0100
"Jim GM4DHJ ..." wrote:

when the transformer went in my TS520SE

Your what?

yes that ....

On Sat, 24 Jun 2017 17:01:44 +0100, Davey wrote:

On Sat, 24 Jun 2017 14:28:27 +0100 "Jim GM4DHJ ..."
wrote:

when the transformer went in my TS520SE

Your what?

For the benefit of those who lack basic google skills (or CBA to
google), it's a 1970s Kenwood "Ham Radio" shortwave transciever designed
to be run off mains power (120/220/240vac). Presumably he meant the mains
transformer in the integrated supply which, in this case would have been
a special to provide heater and HT voltages for the valves (vacuum tubes)
as well as low level DC voltages for the transistorised portions (it was
a 'Hybrid' design relying on valves in the final stages of the
transmitter to achieve its 100W PEP RF output power rating).

--
Johnny B Good

On Friday, 23 June 2017 19:21:28 UTC+1, ss wrote:
Not being electrically savvy but should the `trip` switch on the mains
meter not have clicked in and cut the current off to prevent a fir starting.

There are a number of electrical faults causing fridge fires, the nature of which has changed over time - with high volumes of units sold there will always be failures. Years ago was electromechanical starter switches but since have had issues with PTC's (solid state starter), defrost timers and recently capacitors.

There's no guarantee an rcd would help (at least not 100% of the time) The problem with European designs - as London Fire Brigade (see their website for videos) have been saying for a number of years (backed by research) is that the European standards don't do (or didn't until this year) address the escalation of the fire - the switch from metal to plastic drip trays is one issue as is the use of twin wall polypropylene backs and pentane blown insulation. The refrigerant generally doesn't cause explosions (although it can) as it only gets released once the appliance is fully alight.

In the US design standards (UL 250) are influenced more by insurers (i.e underwriters limited) - the stats would seem to suggest that US fridges are safer. i.e. Components likely to fail are separated from easily ignitable materials

See:

https://www.ior.org.uk/app/images/do...n%20final..pdf