Bloody smoke alarms.

[kreed]

On Wednesday, June 20, 2012 12:44:57 PM UTC+10, Phil Allison wrote:

"Stupider than Anyone Else"


Of course, mains powered detectors are supposed to be installed by a
duly licensed person. That is fair enough, but when I was
investigating the detectors, I was amazed to find that for most of
them, the manufacturers tell you that replacing the backup battery
must also only be done by a licensed sparky!

I don't think the law has anything to say about replacing batteries in
such detectors. More likely the manufacturer just doesn't want to get sued
if someone electrocutes themselves.


** Mains powered detector/alarms are installed with permanent connection to
the AC supply and all the internal circuitry is live at 240 volts, so it is
not safe or permissible for un-unlicensed person to work on them.

Usually, switching off the relevant lighting circuit at the fuse box renders
them harmless to handle but in law you should not do this.

In some examples, replacing the ( 10 year lithium ) battery involves a
soldering operation.

.... Phil

On Wednesday, June 20, 2012 12:44:57 PM UTC+10, Phil Allison wrote:

"Stupider than Anyone Else"


Of course, mains powered detectors are supposed to be installed by a
duly licensed person. That is fair enough, but when I was
investigating the detectors, I was amazed to find that for most of
them, the manufacturers tell you that replacing the backup battery
must also only be done by a licensed sparky!

I don't think the law has anything to say about replacing batteries in
such detectors. More likely the manufacturer just doesn't want to get sued
if someone electrocutes themselves.


** Mains powered detector/alarms are installed with permanent connection to
the AC supply and all the internal circuitry is live at 240 volts, so it is
not safe or permissible for un-unlicensed person to work on them.

Usually, switching off the relevant lighting circuit at the fuse box renders
them harmless to handle but in law you should not do this.

In some examples, replacing the ( 10 year lithium ) battery involves a
soldering operation.


.... Phil

I have a couple of the lithium ones at home. They have 3 X 1/2 AA lithium cells that are soldered in. One problem is that the case on these is not intended for disassembly / reassembly, but that shouldn't worry anyone here.

Note that if these cells "leak", (rare) a white powdery film will form on the PCB near one of the terminals. the good news is that it doesn't seem to corrode components like normal batteries, the bad news is that heating this with a soldering iron when desoldering can make it explode, and while not a massive explosion, it caused minor stinging on my hand from the flying particles so these could damage your eyes, so cover up if you are going to unsolder old lithium cells.

 

[kreed]

On Wednesday, June 20, 2012 2:44:15 PM UTC+10, Phil Allison wrote:

"kreed"

in QLD it does, in the rental tenancies act.


** The regulations in Qld include an obligation on tenants to replace flat
and nearly flat batteries in smoke alarms.

However, it can be taken for granted that the particular alarm must have a
user re-replaceable, readily available battery AND that there is no unusual
hazard involved for the user in so doing.

AC powered alarms with back up batteries that are live at 240V AC when the
case is opened are not part of the deal.


... Phil

They are in my opinion dangerous, unless the AC part uses transformer isolation, and is insulated so it cant be touched when opened, then they are a risk to the consumer, even more so as they can't be unplugged like normal appliances.


Fortunately the ones I have, and have seen to date will "unplug" safely when removed from the base,

They have to be removed from the base (disconnecting mains in the process), in order to access the battery compartment.

 

[keithr]

On 20/06/2012 3:18 PM, kreed wrote:

On Wednesday, June 20, 2012 2:44:15 PM UTC+10, Phil Allison wrote:
"kreed"

in QLD it does, in the rental tenancies act.


** The regulations in Qld include an obligation on tenants to replace flat
and nearly flat batteries in smoke alarms.

However, it can be taken for granted that the particular alarm must have a
user re-replaceable, readily available battery AND that there is no unusual
hazard involved for the user in so doing.

AC powered alarms with back up batteries that are live at 240V AC when the
case is opened are not part of the deal.


... Phil


They are in my opinion dangerous, unless the AC part uses transformer isolation, and is insulated so it cant be touched when opened, then they are a risk to the consumer, even more so as they can't be unplugged like normal appliances.


Fortunately the ones I have, and have seen to date will "unplug" safely when removed from the base,

They have to be removed from the base (disconnecting mains in the process), in order to access the battery compartment.

If they have a replaceable battery then it should be possible to do it

safely without having to turn the power supply off. There are numerous
ways of doing this, it ain't rocket science.

 

[Phil Allison]

"keithr"

AC powered alarms with back up batteries that are live at 240V AC when
the
case is opened are not part of the deal.


If they have a replaceable battery then it should be possible to do it
safely without having to turn the power supply off. There are numerous
ways of doing this, it ain't rocket science.

** You are 100% correct.

At my previous address, the installed smoke alarm was of the type that are
somewhat dangerous but have no replaceable battery. One day it went into
slow beep mode, 20 minute intervals.

A sparky came and replaced it and let me keep the old one.

Turned out a 470nF class X2 cap in the AC feed had gone open circuit.

So I fixed it and still have it in a cupboard, too cute to chuck out.


..... Phil

 

[Andy Wood]

keithr <user@domain.invalid> wrote:

.. . .

If they have a replaceable battery then it should be possible to do it
safely without having to turn the power supply off. There are numerous
ways of doing this, it ain't rocket science.

Indeed. The old detector I replaced had a sliding but non-removable
plastic tray for the 9V battery. To replace the battery, this tray
slid out of the side of the detector. With the tray fully extended,
you might have been able to poke a bit of wire into the thing and
contact a live wire, if you really tried, but then you could do the
same with a GPO too.

However, I prefer the way the new one works. The main part of the
detector flaps down from the base and in the process an internal plug
is pulled out, totally disconnecting the mains. It is not so much that
I think this makes it safer to replace the battery, but that it gives
an easy way to turn the thing off if you ever need to do that.

Andy Wood
woodag@trap.ozemail.com.au

 

[fred]

Andy Wood <woodag@trap.ozemail.com.au> wrote:

The other thing that gets me about smoke detectors, is how the
suppliers can give a very long warranty, knowing full well that you
are probably not going to make a claim on that. To make a claim, they
ask you to return the faulty device to them in outer woop woop.
Ionisation detectors cannot be posted, because some rule-making idiot
does not know the difference betweens a tiny speck of Americium and 10
kilos of weapons-grade uranium.

Can ten kilos of weapons grade uranium even exist in the same post pack
for more than a microsecond

 

[Jasen Betts]

On 2012-06-23, fred <fred@fred.com> wrote:

Andy Wood <woodag@trap.ozemail.com.au> wrote:


The other thing that gets me about smoke detectors, is how the
suppliers can give a very long warranty, knowing full well that you
are probably not going to make a claim on that. To make a claim, they
ask you to return the faulty device to them in outer woop woop.
Ionisation detectors cannot be posted, because some rule-making idiot
does not know the difference betweens a tiny speck of Americium and 10
kilos of weapons-grade uranium.


Can ten kilos of weapons grade uranium even exist in the same post pack
for more than a microsecond

critical mass is a bit higher than that
http://en.wikipedia.org/wiki/Critical_mass

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