Posted By David Adams
Various fire safety groups advise that office equipment (and domestic TV's etc) should be unplugged as well as switched off over night or if not in use for prolonged periods. This sounds sensible but is it OTT? Can anyone explain what the problem is and how likely / serious it could be.

Posted By David Adams
Thanks for that. However my original question was more to do with asking why isn't just switching off good enough, why do the experts ask us to unplug?

Posted By Geof
OTT

Posted By Delwynne
Yes, but that should be reported by the users when carrying out their visual inspections of electrical equipment prior to use?
Sorry, really shouldn't be sarcastic. I have to say I agree with geoff - it's completely over the top. Maybe we should just ask the electricity board to switch off the mains when we go home just in case?

Posted By David Adams
Thanks Geof, I always thought that those plastic plug protectors were to stop my kids from jamming pencils into the sockets! I get the feeling that someone is getting a bit frivolous bearing in mind it is Frdiay afternoon. Keep taking the dried frog pills!! Is there anyone sensible out there??

Posted By Jimmy
Reasonably good advice David. Probably the sensible answer is that not all socket outlets are specified to be switch type during installation. If they are un-switched this would mean that the plug and flex remains in a live condition. In alot of office environments, cables become coiled and twisted, this can be a source of heat. This can only be remedied by routine tours of the office or limiting the lenghts of cables, extensions etc. Some computer power installations do have have installations whereby the sockets are un-swiched to maintain system integrity, so bang goes the experts advice to unplugging every thing.
Do you know what an angry IT manager looks like?

Posted By John Murgatroyd
An increasing amount of electronic equipment features a power supply called "switched mode", this doesn't use a transformer to step the voltage down, instead it uses semiconductors to sense when the ac voltage goes higher than needed then switches it off until the voltage has dropped to the needed volts again (simplified description).
Most pcs' (if not all) use this method and the small chargers for mobile phone use it a lot as well. A large (and getting larger) amount of imported gear has no on/off switch, just one that disconnects the system and leaves the psu in-line with the mains. Most tv's have an on/off mains switch but people use the "standby" switch instead. Which leaves the tv on as far as the mains is concerned, but off as far as the user is concerned. I just switch the gear off at the socket, no socket switch then unplug as well. But chech what gear is plugged in...you may be switching the office router off...bad move !

Posted By Jimmy
Poor David he's now a fully qualified elec eng, and all for free!!!!!!!

Nice one

Posted By Geof
Each night my grandfather used to switch the radio off at the mains and disconnect the plug. Then he would pull out the aerial and .... off tune the station dial.

In all the time he did that (I would guess at 50 years) the house never once got struck by lightning - so it must have worked.

Posted By John Webster
So will unplugging appliances make you less likely to be harmed by fire? And is it worth the hassle? I happened to be looking at fire statistics to help me with hospital fire risk assessments & training, and maybe can bore you with a few figures.

Nearly 90% of all fire casualties occur in dwellings. The majority of casualties (70%) die from or suffer effects of smoke.

Fires due to faulty appliances and leads account for 7% of fire casualties. Arson, chip pans, smoking materials, candles and kids playing with fire cause the bulk of fires.

90% of fires are confined to the room where it started.

A significant proportion of appliance fires break out in washing machines and tumble driers. These rarely result in casualties - presumably because they happen in use, in the day, tend to be in utility rooms, or are confined to the appliance itself etc.

Electric blanket fires frequently cause casualties.

TVs are the next most likely appliance to catch fire, whereas other electronic and electrical equipment (eg videos, computers) hardly get a mention. TVs feature for two reasons. There are a lot of them (many homes have half a dozen of the things - including in the bedrooms), and because of the high voltage on the tube they are more efficient than a Dyson at collecting dust. Slightest fault and the dust can catch fire. We also tend to put things on them, or tuck them in the corner next to the curtains to increase the chance of a fire taking hold.

Fridges and freezers are rarely involved in fires, but when they are, they burn more intensely than any other appliance (peak energy 2000kW) and so are more likely to cause a fire that spreads.

The peak time for fire casualties is midnight - 5 am. Typically at this time are fires from smoking materials, chip pans (snack after the pub and fall asleep) and TVs left on standby.

The age groups most disproportionally harmed by fire are the elderly, followed by pre-school age children.

Most (85%) domestic fire casualties were in premises where there was not a fully functioning smoke detector.

So if have few enemies, you don't smoke or fry and your electric blanket is regularly checked then you might want to consider switching off or unplugging the TV. Of course it is prudent, and thrifty, to disconnect other not-in-use appliances, but there does not appear to be significant evidence of a fire risk, especially one likely to cause harm.

For those we must leave on, the message cannot be clearer. Working, properly located smoke detectors save lives.

Posted By Jimmy
Fine and well but, when my chicken was still in its raw state after about an 2 hours in the oven, I realised I'd turned the cooker off, but set the timer. Any way I blamed the dog.

Posted By George Wedgwood
Looks like we are just going to have the daily chore of resetting the video clock, radio alarm, oven clock, microwave clock, burgular alarm........ Remember that electrical equipoment is supposed to be designed to be safe in all reasonable use and that includes leaving it on and plugged in - and on standby if designed to do so. If the supply is properly protected, and the system connected properly, a fault should not cause a fire.

Posted By John Webster
George
The data I referrred to indicated no significant fire risk from electrical and electronic appliances other than as mentioned in my previous posting. So leave them on if switching them off causes hassle.