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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only.

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Old 2nd Jan 2010, 11:30 am   #1
crockhamtown
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Default Fire risk

When we leave the house, we worry about our little dog being caught in a fire through us leaving a radio on.

So my question is can old radios catch fire through leaving then on?

The radio is a Sony Digimatic FM/MW/LW digital clock radio model ICF-C3L, and must be more than 25 years old.

It works directly from mains electricity so 240v is going into the radio. I assume then that a transformer inside reduces the voltage.

I am slavish about turning electric devices off when we leave the house but if you do it to this radio it loses the time and you have to reset it.

I would like to keep on using it so if anyone could advise on its saftey I would be grateful.

Many thanks
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Old 2nd Jan 2010, 12:22 pm   #2
paulsherwin
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Default Re: Fire risk

Like VCRs and many other devices, clock radios are intended to be permanently connected to the mains. A fire as a result of a fault is extremely unlikely, though not impossible. I wouldn't worry about it.

Even old valve radios are unlikely to cause a fire if faulty, though I wouldn't leave one switched on and unattended.

Paul
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Old 2nd Jan 2010, 12:34 pm   #3
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Default Re: Fire risk

I'd agree with Paul. The risk is very small for a low current appliance like a clock radio.

I have to confess though that I'm also paranoid about fire risk - probably after the house next door went up when I was a kid (faulty immersion heater).

It was always a PITA to switch the older clock radios off, because you had to reset the clock (etc) on most models. I've got round that problem by buying a Pure Chronos II. (Dab 2 ready). The time is stripped off of DAB signal when it's switched on, so you can switch it off without any hassle - All the alarm settings are stored in NVRAM
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Old 2nd Jan 2010, 1:31 pm   #4
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Default Re: Fire risk

The risk is very small I would say, and can be reduced even further by ensuring the correct value fuse is fitted to the mains plug, certainly not a 13A one! For an appliance like this use a 2 or 3A fuse. You used to be able to get 1A plug fuses but I havent seen these for a while.
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Old 2nd Jan 2010, 1:32 pm   #5
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Default Re: Fire risk

A high percentage of House fires are caused by electricity either appliances , consumer units or wiring.

Personally I would rather consider the safety of my dog than the inconvenience of resetting the clock, I would assume the clock is not your only indication of time.

A very good customer of mine who is absolutely meticulous about these things was unfortunate to have a fire just over 8 weeks ago which started in the integral garage at the consumer unit . Luckily a neighbour was alert enough to call the brigade and rescued his cats.

To actually raise the question it obviously bothers you so put your mind at ease and turn the radio off.

Electricity faults can generate heat due to sparking for instance, the heat source can be intense enough to cause something more flammable to catch fire nearby.

Mike

Last edited by MichaelR; 2nd Jan 2010 at 1:37 pm. Reason: addition
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Old 2nd Jan 2010, 2:10 pm   #6
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Default Re: Fire risk

It's impossible to have a risk free life. It's up to each individual to decide what level of precautions to take.

I regard any transistor kit as being reasonable safe to leave switched, but only if there's good reason to, for example anything with a clock and no back up.

Valve radios I switch off and unplug when I'm not present. I wouldn't leave a washing machine running unattended either as one of mine suffered a disconnection between the outlet hose and the drum. On fill cycles the water just poured out on to the floor as the level sensor never activated. Fortunately I was there and saw what was happening.

Just personal opinions. As I said everybody has to make up their own mind, which is why you're getting apparently conflicting advice here.

As for domestic fires the majority are still caused by chip pans and cigarette ends.
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Old 2nd Jan 2010, 2:38 pm   #7
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Default Re: Fire risk

Quote:
Originally Posted by Station X View Post
As for domestic fires the majority are still caused by chip pans and cigarette ends.

That is not correct, look at the national Stats.

http://www.statistics.gov.uk/CCI/nscl.asp?ID=7152

If you check out the non fatal figures smoking incidents amount to about 8%

70% are electricaly related. the highest incident being due to electric cookers and I do not think that can be also attributed to chip pans as only about 8% is gas cookers

Mike
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Old 2nd Jan 2010, 3:08 pm   #8
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Default Re: Fire risk

A typical small appliance like a clock radio will contain lots of low rated components. If these components fail they may burn out, but this will happen too quickly to start a fire outside the unit, or the heat generated will be insufficient to start a fire. Some people would still consider this a fire though, as there would be smoke and burning smells.

Most major fires caused by domestic electronic equipment seem to be caused by TVs. These have large switch mode power supplies which can deliver a lot of current for a long time in a fault condition, and they are typically located near curtains which are easy to ignite.

Paul
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Old 2nd Jan 2010, 3:09 pm   #9
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Default Re: Fire risk

Stats prove exactly what Staticians want them to so I'd take such figures with a pinch of salt. Fag ends get destroyed in fires and the mess from putting the fire out. The victims are also hardly likely to admit going to sleep and dropping their cancer stick down the side of the sofa to their insurers.
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Cigarettes are IMHO responsible for many more house fires than claimed.

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Old 2nd Jan 2010, 3:09 pm   #10
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Default Re: Fire risk

The figures for ALL dwelling fires are here:-

http://www.statistics.gov.uk/STATBAS...eets/D5830.xls

Only about 10% are down to FAULTY appliances. Chip pan fires come in at about 15%. Many fires are down to cookers, but not because they're faulty.

I was actually quoting from a family member who's a retired firefighter. He told me that so long as I didn't smoke or use a chip pan I was unlikely to suffer a house fire. I guess he assumed that I wouldn't leave combustible materials near a cooker. Tea towels are the favourite apparently. Some people dry them in the oven.
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Old 2nd Jan 2010, 3:17 pm   #11
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Default Re: Fire risk

Quote:
Originally Posted by Jonster View Post
....... You used to be able to get 1A plug fuses but I havent seen these for a while.
Available from CPC, p/n FF01691 in packs of 10. I use these for all my restored mains-powered radios, and the majority of our household electrical items.

CPC also sell these in packs of 1,000!

Edward
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Old 2nd Jan 2010, 3:21 pm   #12
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Default Re: Fire risk

I notice from that that the biggest cause of Electrical Fires are caused by 'misuse of electrical appliances'. This will include cables pulled tight round corners, adaptor 'christmas trees', misuse of cookers in a number of ways.... The next biggest is faulty leads. The way some people wire plugs I am surprised that isn't more, frayed cables, the usual stuff.

David makes a good point about Statistics, one that I was going to make too. There's a book called 'How To Lie With Statistics'. Well worth a read.

Going back to the original question, as long as your mutt can't pull anything off or chew leads, then with a transistor/IC set up, you have no need to worry.

Cheers,

Steve P.
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Old 2nd Jan 2010, 3:32 pm   #13
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Default Re: Fire risk

Well I seem to be in a minority here.

I do not have any relatives who are fire fighters so I cannot answer that one.

Two sets of national stats show different results , their definitions of categories lead to specualtion maybe.

Smokers cause most of the fires in the UK so the concensus is leave the Telly and the radio on for the dog but keep his fags and chip pan locked up .

Let us hope you do not suffer a fire

Mike

Last edited by MichaelR; 2nd Jan 2010 at 3:34 pm. Reason: addition
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Old 2nd Jan 2010, 4:01 pm   #14
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Default Re: Fire risk

Hello
The Sony clock radio you have is fitted with a mains transformer, which includes a thermal fuse built into the primary winding of the transformer. This fuse will melt or blow if the temperature of the transformer climbs to an unsafe level and disconnect the appliance from the mains long before the temperature gets anywhere near that what would cause a fire. This fuse is designed to protect the transformer and the appliance against sustained overloads due to faulty components and obstructed ventilation; the mains fuse is there to protect the cable against short circuit.
The clock radio is rated for 240/250-volt mains supply, which is a good thing as modern 230-volt appliances do overheat on the high mains (253 volts) where I live.
So as long as the radio is in a well, ventilated area, the ventilation holes are not obstructed and the cable is in good condition with a small value fuse fitted to the plug, I am sure you will have nothing to worry about.

Regards Stan.
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Old 2nd Jan 2010, 4:01 pm   #15
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Default Re: Fire risk

I worked with a fireman for over 27 years. He also informed me that the majority of house fires were caused by smoking and chip pans. They seem to be more prevalent with electric cookers due to people turning them on full power to heat them up due to the delay and then forgetting about them. We had a very serious fire in our London home caused by just this type of incident with a chip pan/electric cooker. Fags down the sides of armchairs and sofas are another common cause usually because guys fall asleep in front of the telly and the rest is history. My mate told me that a call between 2am and 4am was usually a serious house fire due to this very cause.
Statistics are useless. All evidence of cigarette abuse were generally destroyed in a house fire and providing there was no suspicion of arson it was usually put down to 'electrical fault' due to the masses of burnt wiring evident in the remains of the incident. This 'clears the way' for the unfortunate victim to claim from his insurance company without a time delaying saga of technical inquests.
A business friend of mine arrived home one evening to the smell of burning electrical equipment combined with the loudest 50c/s hum you have ever heard. This was coming from the electric meter under the stairs which was burning and sparking. It was about to catch fire. The Electricity board were around in moments when he phoned them. They could hear the hum down the phone line. It turned out to be a loose connection in the main 100amp cable input from the street to the meter via the board fuse. Similar arcing from loose connections can occur with consumer units a fault I experienced a number of times when installing new television receivers. [microsecond flashing lights when load switched on]
Most small clock radio's of the period you mention have a 'self destruct' mains transformer that has a non replaceable thermal fuse buried in the primary winding. If a fault occurs this will go O/C cutting the power off long before overheating occurs.
I would add that I have a Toshiba clock radio that has been in continual service since 1973 with no problems.
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Old 2nd Jan 2010, 4:17 pm   #16
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Default Re: Fire risk

I recall seeing an article where a fireman said they had to complete paper work for every call giving probable cause of fire. If in doubt tick electrical cause was his response.

Given that the fire brigade have advertising warning about overloading 13A sockets, which is not possible with fused plugs & adaptors. I doubt the accuracy of their reports.
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Old 2nd Jan 2010, 4:23 pm   #17
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Default Re: Fire risk

Can we stay on topic please? The original member was worried about his clock radio.

Chip pan fires, cigarette butt ends, smoking consumer units, fire brigade reports etc etc have nothing to do with vintage radio.
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Old 2nd Jan 2010, 6:33 pm   #18
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Default Re: Fire risk

Hi,

In my opinion, the risk is small and it's not worth worrying about it.

Modern electronic equipment (my definition of 'modern' is anything made in the last 20-30 years) is designed to meet various safety standards. This includes such things as the use of 'self-extinguishing' materials, thermal fuses buried inside mains transformers and so on.

UK mains wiring is unusual (in the world-wide scheme of things) in that the power outlet circuits are rated at 30A. That could pose a problem if it weren't for the fact that fused plugs are used. The cable between the appliance and the plug isn't rated at 30A; but the fuse is there to prevent the cable catching fire should a fault develop in the appliance.

So the fuse should be chosen with regard to the current rating of the cable. In this case, a 3A fuse would suffice (though 1A or 2A could be used, if you can find them.)

Don't assume that anything you've bought which came with a plug already attached is fitted with correct fuse. Check it! (Just a few weeks ago, I bought a 6V mains adapter to power my digital camera and found the plug was fitted with a 13A fuse!)

Mains plugs should be fitted correctly. What is 'correctly' though? The plug is cleverly designed such that if the cable is pulled hard, the live connection disconnects before the neutral (and the earth last, if present.) That relies on the live and neutral (and earth) wires being cut to the correct length; the live wire should be short and run straight to its terminal, the neutral wire should be longer and have some slack in it (and the earth wire, if present, longer still and also slack.)

Something I've encountered many times with older equipment which has had a plug on it for years, is the screw terminals working loose. More often than not, it's only the neutral terminal. The neutral pin wobbles around when the plug is disconnected/connected; the live terminal is isolated from movement by the fuse, so this could be a factor. Copper also 'cold flows' when subject to pressure; that probably explains why the live terminal is sometimes loose as well.

So it's worth checking that the terminals are tight on any appliance that's had a plug on it for a long time.

(Note that this is unlikely to cause a fire, more likely just a buzzing/fizzing noise from the plug and maybe a bit of smoke and a smell.)

Coming right down the 'risk' scale, metal (such as copper wire) can suffer fatigue failure. Open up a paperclip, then bend/straighten it repeatedly. It'll break.

I only mention this due to one (unusual and arguably extreme) example. Many years ago, the wiring on my sister's hairdryer failed (spectacularly!) Due to repeated movement, the wiring fractured. This caused internal arcing which blew out a chunk of both inner and outer insulation, leaving a hole in the side of the cable and only the neutral wire attached, just where the cable exited the plug.

Even further down the 'risk scale'; soldered joints can and do fail due to thermal cycling. In rare circumstances, this can cause arcing (though usually just causes the appliance to malfunction until given a good hard thump!)

So I could argue that the clock radio itself is very unlikely to pose a risk of fire, especially as it's clearly designed to be left permanently connected. The risks can be further reduced by ensuring that the mains cable is in good condition, the plug is correctly fitted, the terminals tight and the correct rating fuse is fitted.

Then I could be a bit controversial and argue that the (already small) risk may be further reduced by leaving it plugged in! That would reduce the possibility of movement-induced loosening of the terminals in the plug, movement-induced fatigue failure of the wiring and thermal-cycling induced failure of soldered joints.

It's up to you to weigh up the risks and make your own decision. Personally, I leave equipment plugged in and a lot of it running 24/7. I run the odd 'net-facing server; so there's always two network switches, an ADSL modem/router and at least one computer left on 24/7 even if we go on holiday (along with the central heating controller, burglar alarm, a TV distribution amplifier, two digital clock-radios and a couple of plug-in timers switching lights on and off.) I don't worry about any of this but I know the wiring/fuses/plugs etc. have been checked, the equipment itself is unlikely to fail; and if it does it should 'fail safe' by design.

However, I don't leave vintage equipment plugged in or operating unattended; where 'vintage' means anything with valves in it along with some (sixties) solid-state gear which appears to pre-date a few safety regulations and approvals.

(To put the risk of electrical fire as I perceive it into perspective; I'm far more worried about being directly under the approach for Leeds-Bradford airport... and that's "not really worried at all" as aircraft don't fall out of the sky particularly often.)

Regards, Kat
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Old 2nd Jan 2010, 6:52 pm   #19
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Default Re: Fire risk

Does the risk increase with the age of the equipment? That clock is 25 years old , what were safety standards like 25 years ago?.

Proof of the pudding is if you had a fire you would admit to the Insurance company if asked that you had left certain electrical equipment switched on because they do work on statistics.
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Old 2nd Jan 2010, 7:06 pm   #20
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Default Re: Fire risk

Hi,

25 years ago works out as 1985; I'd argue that this means 'modern'. I've repaired plenty of equipment from around then. Just take a look at a service manual from around the time; there are components (on the mains side, but often elsewhere) marked with an exclamation mark in a triangle, meaning 'safety-critical, replace with an identical part', fusible resistors, fusible links, thermal fuses and so on. Closely examine some 'safety-critical' part like a mains switch; it's plastered with tiny emblems denoting safety approval from various world-wide bodies.

By 1985, electronic equipment was (IME) designed/manufactured to standards which aren't far off what's current today (and arguably better, but that'd be getting off-topic again...)

It may be worth mentioning that I started work in the electronics industry (design/manufacturing) in 1986. By then, we were having to use fire-retardent and 'self-extinguishing' materials (wiring, components, circuit boards etc.) and any 'bought-in' components had to have various safety approvals. (The equipment itself then having to be submitted to various bodies for testing/approval before we could sell it.)

A note about 'fire-retardent' and 'self-extinguishing'; that doesn't mean it won't catch fire; what it does mean is that once the heat-source (electical current) is removed, any actual fire will cease and can't spread. Obviously, if a higher-rating fuse has been fitted (or the original wrapped in foil!), inept 'repairs' carried out (bypassing 'safety critical' parts or replacing them with incorrect types); excessive current can continue to flow when, by design, it shouldn't.

Some equipment I've had brought to me for repair with the report "it caught fire"; investigation revealed that a failure elsewhere caused some small component to overheat, causing no more than a bit of smoke and a smell. The component quickly failed and/or a regular or thermal fuse blew, current flow ceased and there was no chance of a fire developing/spreading due to the use of 'fire-retardent'/'self-extinguishing' materials. It's fairly common for people to equate "smoke and a burning smell" (incorrectly) with "fire" though.

Regards, Kat
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