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Surge protection
I have a surge protection extension in the kitchen, used for TV,
decoder box and radio. It is very old. I read here recently that these devices may present a fire risk. To my knowledge we have never had any surges or spikes. Should I be ditching this device? |
Surge protection
On Sat, 02 Feb 2019 11:10:18 +0000, Scott
wrote: I have a surge protection extension in the kitchen, used for TV, decoder box and radio. It is very old. I read here recently that these devices may present a fire risk. To my knowledge we have never had any surges or spikes. Should I be ditching this device? Most small PSU's carry surge protection anyway, or are so cheap and cheerful that they don't need it. The major risk to small appliances comes from Aerial inputs or Telephone connections. If the unit is easily dismantled, look at the innards. The surge protection will in all likelyhood be a MOV, choke and fuse. Providing the cable looks substantial enough, the fuse is of a reasonable value and the MOV is mounted sensibly, ie away from easily ignited components, then the unit is going to function as a good multi way adaptor. Dont expect any sudden failiure of the supplied equipment if you ditch it though. A final point, I have found that if you change things electrically, even turning off things that run 24/7, it seems to invite seemingly none related problems, So if you get rid, and BBC1 starts showing repeats................ :-) AB |
Surge protection
"Scott" wrote in message ...
I have a surge protection extension in the kitchen, used for TV, decoder box and radio. It is very old. I read here recently that these devices may present a fire risk. To my knowledge we have never had any surges or spikes. Should I be ditching this device? You will had had thousands of spikes. Every time your 'fridge compressor starts you'll get a detectable spike. Whether they are of significant magnitude is the question. The MOVs in surge suppressors do have a finite capacity for absorbing spike energy, and at end of life can go s/c so always should have a fuse in line, but in an extension it presumably is via a fused plug Andrew |
Surge protection
On Sat, 2 Feb 2019 12:53:20 -0000, "Andrew Mawson"
wrote: "Scott" wrote in message ... I have a surge protection extension in the kitchen, used for TV, decoder box and radio. It is very old. I read here recently that these devices may present a fire risk. To my knowledge we have never had any surges or spikes. Should I be ditching this device? You will had had thousands of spikes. Every time your 'fridge compressor starts you'll get a detectable spike. Whether they are of significant magnitude is the question. The MOVs in surge suppressors do have a finite capacity for absorbing spike energy, and at end of life can go s/c so always should have a fuse in line, but in an extension it presumably is via a fused plug Andrew The MOV's are VDR's, and as long as they are not called on to dissipate more than their rating, they will work forever. They are simply a Voltage dependent resistor. They have an infinite lifespan if not overloaded. The vertical oscillator/ output stage in old valve TV's used them on the triode feed from the boost rail, specifically to stabilise the Voltage. These never, ever failed. There was one more in the frame stage, the thing would be across the primary of the field output transformer. This handled spikes, lots of them, 25 per second. They never failed either. VDR's or MOV's do not simply fill up with spikes and fail in their twilight years. They are a Voltage dependent resistor and whereas your 10K is always 10K whether it has one or ten Volts across it, a VDR is what it say's, "Voltage dependent". AB AB |
Surge protection
In article ,
Scott writes: I have a surge protection extension in the kitchen, used for TV, decoder box and radio. It is very old. I read here recently that these devices may present a fire risk. To my knowledge we have never had any surges or spikes. Should I be ditching this device? Metal Oxide surge suppressors are a fire risk. Seen a couple of socket blocks that would have started fires if there was something flammable nearby. They are also almost completely pointless. They only came about because manufacturers found they could add a component costing 10-20p, and charge £5 more for the product. -- Andrew Gabriel [email address is not usable -- followup in the newsgroup] |
Surge protection
On 02/02/2019 13:16, Archibald Tarquin Blenkinsopp wrote:
The MOV's are VDR's, and as long as they are not called on to dissipate more than their rating, they will work forever. But their rating is often for as little as 10 to 100 spikes. They are simply a Voltage dependent resistor. They have an infinite lifespan if not overloaded. That's the key "if not overloaded". Define an overload. VDR's or MOV's do not simply fill up with spikes and fail in their twilight years. MOVs have a capacity to deal with a specified number of spikes (of a certain energy) before they fail. The problem is often the mechanical construction of the circuit. When a MOV fails it often blows apart. If it is mechanically constrained by other components and is still held physically together and can start sparking. They are a Voltage dependent resistor and whereas your 10K is always 10K whether it has one or ten Volts across it, a VDR is what it say's, "Voltage dependent". But the characteristic is the wrong way around for infinite life. High value resistance at lower voltages = low power dissipation Low value resistance at higher volatges = high power dissipation -= bang! -- mailto : news {at} admac {dot} myzen {dot} co {dot} uk |
Surge protection
On Sat, 2 Feb 2019 14:44:25 +0000, alan_m
wrote: On 02/02/2019 13:16, Archibald Tarquin Blenkinsopp wrote: The MOV's are VDR's, and as long as they are not called on to dissipate more than their rating, they will work forever. But their rating is often for as little as 10 to 100 spikes. They are simply a Voltage dependent resistor. They have an infinite lifespan if not overloaded. That's the key "if not overloaded". Define an overload. VDR's or MOV's do not simply fill up with spikes and fail in their twilight years. MOVs have a capacity to deal with a specified number of spikes (of a certain energy) before they fail. The problem is often the mechanical construction of the circuit. When a MOV fails it often blows apart. If it is mechanically constrained by other components and is still held physically together and can start sparking. They are a Voltage dependent resistor and whereas your 10K is always 10K whether it has one or ten Volts across it, a VDR is what it say's, "Voltage dependent". But the characteristic is the wrong way around for infinite life. High value resistance at lower voltages = low power dissipation Low value resistance at higher volatges = high power dissipation -= bang! In a domestic situation, the life would be infinite. Pulse levels of hundreds of Amps have to flow before a cumulative effect takes place. By the time cable resistance and plug contact resistance is taken into account, there just wouldn't be hundreds of Amps available. I have never seen one obliterated in a domestic environment. They do get zapped on factories where the wiring is more substantial and noise levels are high, even so I have yet to see a periodic maintainance ticket for MOV replacement anywhere. AB |
Surge protection
Don't see why? They can only start to get hot, at which time one hopes the
fuse blows and there you are. If there are some which are not protected, then I'd not want to use them anyway. I found back in the 70s a little vdr in the plugs was OK and protected against mode spikes, after all they are short lived and hence the current they take is not going to be an issue, and in any case if the over voltage lasted the fuse would once again blow. I do however like the ones with a filter as well as surge protection as they seem to stop digital stuff misbehaving due to noise getting in from the mains. I guess this is increasingly an issue with all these internet over the mains adaptors which should all be outlawed in my view. Brian -- ----- -- This newsgroup posting comes to you directly from... The Sofa of Brian Gaff... Blind user, so no pictures please Note this Signature is meaningless.! "Scott" wrote in message ... I have a surge protection extension in the kitchen, used for TV, decoder box and radio. It is very old. I read here recently that these devices may present a fire risk. To my knowledge we have never had any surges or spikes. Should I be ditching this device? |
Surge protection
Yes indeed. The only failure mode, assuming no lightning strikes or similar.
I have encountered is going open circuit due to the wire becoming internally detached. Far more common are failure of the filters that often are used as well. In these the capacitors go leaky and heat up making usually magic very smelly smoke before the fuse pops. A very dangerous device from many years ago, though I never realised it till it failed was the pifco rechargeable torch. It had a two pin plug on one end withed a cover and inside a 'lossless' dropper in the form of a capacitor, then a tiny circuit that made around 7.5v which charged up some nicads. Fine until one day the capacitor went down. put huge mains on the semiconductor and the batteries and the whole room filled with smoke and gunge started to leak from the torch dripping onto the carpet. Luckily I way in at the time, but oh, the smell was in my nose for days. the torch had partially melted. No no fuse just a resistor across the pins to discharge any charge left when you unplugged it. I have also found that many shops are being duped into stocking stuff that has CE on it but is rubbish. Take shaver adaptors with no fuse at all, or wall warts with no fusible link, or ones secured together by screws as short as those used for cassette tapes. All very dangerous. Then there was the Eaton PSU from Maplin that dropped all of 1 foot onto a floor and the two halves came apparently seemingly being glued in two little places, exposing the mains terminals of the transformer. I could go on, but really I think worrying about an older adaptor is not what you should be worrying about its the new stuff you need to watch for. My old torch had lasted over 10 years before it died, but many of the current wall warts seem to be good if they last three years. Brian -- ----- -- This newsgroup posting comes to you directly from... The Sofa of Brian Gaff... Blind user, so no pictures please Note this Signature is meaningless.! "Archibald Tarquin Blenkinsopp" wrote in message ... On Sat, 2 Feb 2019 12:53:20 -0000, "Andrew Mawson" wrote: "Scott" wrote in message . .. I have a surge protection extension in the kitchen, used for TV, decoder box and radio. It is very old. I read here recently that these devices may present a fire risk. To my knowledge we have never had any surges or spikes. Should I be ditching this device? You will had had thousands of spikes. Every time your 'fridge compressor starts you'll get a detectable spike. Whether they are of significant magnitude is the question. The MOVs in surge suppressors do have a finite capacity for absorbing spike energy, and at end of life can go s/c so always should have a fuse in line, but in an extension it presumably is via a fused plug Andrew The MOV's are VDR's, and as long as they are not called on to dissipate more than their rating, they will work forever. They are simply a Voltage dependent resistor. They have an infinite lifespan if not overloaded. The vertical oscillator/ output stage in old valve TV's used them on the triode feed from the boost rail, specifically to stabilise the Voltage. These never, ever failed. There was one more in the frame stage, the thing would be across the primary of the field output transformer. This handled spikes, lots of them, 25 per second. They never failed either. VDR's or MOV's do not simply fill up with spikes and fail in their twilight years. They are a Voltage dependent resistor and whereas your 10K is always 10K whether it has one or ten Volts across it, a VDR is what it say's, "Voltage dependent". AB AB |
Surge protection
On Sun, 3 Feb 2019 08:50:02 -0000, "Brian Gaff"
wrote: Yes indeed. The only failure mode, assuming no lightning strikes or similar. I have encountered is going open circuit due to the wire becoming internally detached. Far more common are failure of the filters that often are used as well. In these the capacitors go leaky and heat up making usually magic very smelly smoke before the fuse pops. A very dangerous device from many years ago, though I never realised it till it failed was the pifco rechargeable torch. It had a two pin plug on one end withed a cover and inside a 'lossless' dropper in the form of a capacitor There was a Thorn mains portable TV that used this principle. Brilliant when it worked, it dropped the Volts nicely and enabled the TV to fit into a very small cabinet that was fairly portable. When the cap shorted, the valves and no doubt CRT heaters would compete with the Xmas tree for a "short" while :-) Nearly everything I buy from Ebay has a CE mark. I do get the impression that these are just stamped on as part of the manufacturing process. At least they seem to have seen the limit with my recently purchased dimmer. No tools needed for disassembly, a circuit bare of any frills like suppression, in fact it could be a direct copy from a textbook. At least LW wireless is out of fashion now, it would play havoc with the shipping forecast. The CE mark has become a "CCCe" mark. "Chinese Copied Ce" perhaps ? AB |
Surge protection
On 03/02/2019 10:59, Archibald Tarquin Blenkinsopp wrote:
The CE mark has become a "CCCe" mark. "Chinese Copied Ce" perhaps ? I think you might be confusing the CE mark with the CE mark where the former is a confirmation of European conformity and the other means Chinese Export. Wikipedia has an article on the difference between the two: I believe there is something like a one pixel alteration between the symbols so technically they are different. Nick |
Surge protection
Nick Odell wrote:
On 03/02/2019 10:59, Archibald Tarquin Blenkinsopp wrote: The CE mark has become a "CCCe" mark. "Chinese Copied Ce" perhaps ? I think you might be confusing the CE mark with the CE mark where the former is a confirmation of European conformity and the other means Chinese Export. Wikipedia has an article on the difference between the two: I believe there is something like a one pixel alteration between the symbols so technically they are different. Nick I think that is an urban myth. Tne CE mark from China is still a claim to meet EU standards, whatever the font. If a lot of firms use it dishonestly it loses all value, but the context of use is such that conformity to EU standards is being claimed even if the graphic implementation is sloppy. And they use it because the CE mark is compulsory and can easily be checked, while actual compliance checking is harder. -- Roger Hayter |
Surge protection
On Sun, 3 Feb 2019 11:16:36 +0000, Nick Odell
wrote: On 03/02/2019 10:59, Archibald Tarquin Blenkinsopp wrote: The CE mark has become a "CCCe" mark. "Chinese Copied Ce" perhaps ? I think you might be confusing the CE mark with the CE mark where the former is a confirmation of European conformity and the other means Chinese Export. Wikipedia has an article on the difference between the two: I believe there is something like a one pixel alteration between the symbols so technically they are different. Nick Thank you! I wasn't aware of the difference, I assumed that the stuff was being traded as something produced to EU standards. That explains a lot. On the plus point it seems that we have "control" already, we are still in the EU and freely importing junk :-) AB |
Surge protection
In article ,
Archibald Tarquin Blenkinsopp wrote: On Sun, 3 Feb 2019 08:50:02 -0000, "Brian Gaff" wrote: Yes indeed. The only failure mode, assuming no lightning strikes or similar. I have encountered is going open circuit due to the wire becoming internally detached. Far more common are failure of the filters that often are used as well. In these the capacitors go leaky and heat up making usually magic very smelly smoke before the fuse pops. A very dangerous device from many years ago, though I never realised it till it failed was the pifco rechargeable torch. It had a two pin plug on one end withed a cover and inside a 'lossless' dropper in the form of a capacitor There was a Thorn mains portable TV that used this principle. Brilliant when it worked, it dropped the Volts nicely and enabled the TV to fit into a very small cabinet that was fairly portable. When the cap shorted, the valves and no doubt CRT heaters would compete with the Xmas tree for a "short" while :-) Nearly everything I buy from Ebay has a CE mark. I do get the impression that these are just stamped on as part of the manufacturing process. At least they seem to have seen the limit with my recently purchased dimmer. No tools needed for disassembly, a circuit bare of any frills like suppression, in fact it could be a direct copy from a textbook. At least LW wireless is out of fashion now, it would play havoc with the shipping forecast. The CE mark has become a "CCCe" mark. "Chinese Copied Ce" perhaps ? The Ce bit means "Chinese Export". -- from KT24 in Surrey, England "I'd rather die of exhaustion than die of boredom" Thomas Carlyle |
Surge protection
On Sun, 03 Feb 2019 11:51:17 +0000 (GMT), charles
wrote: In article , Archibald Tarquin Blenkinsopp wrote: On Sun, 3 Feb 2019 08:50:02 -0000, "Brian Gaff" wrote: The CE mark has become a "CCCe" mark. "Chinese Copied Ce" perhaps ? The Ce bit means "Chinese Export". So I gather! A bit of enlightenment I have Mr Odell to thank for. Just when you think you know everything, someone comes along to tinkle on One's bonfire :-) AB |
Surge protection
"Brian Gaff" wrote in message ... Yes indeed. The only failure mode, assuming no lightning strikes or similar. I have encountered is going open circuit due to the wire becoming internally detached. Far more common are failure of the filters that often are used as well. In these the capacitors go leaky and heat up making usually magic very smelly smoke before the fuse pops. A very dangerous device from many years ago, though I never realised it till it failed was the pifco rechargeable torch. It had a two pin plug on one end withed a cover and inside a 'lossless' dropper in the form of a capacitor, then a tiny circuit that made around 7.5v which charged up some nicads. Fine until one day the capacitor went down. put huge mains on the semiconductor and the batteries and the whole room filled with smoke and gunge started to leak from the torch dripping onto the carpet. Luckily I way in at the time, but oh, the smell was in my nose for days. the torch had partially melted. No no fuse just a resistor across the pins to discharge any charge left when you unplugged it. I have also found that many shops are being duped into stocking stuff that has CE on it but is rubbish. Take shaver adaptors with no fuse at all, or wall warts with no fusible link, or ones secured together by screws as short as those used for cassette tapes. All very dangerous. Then there was the Eaton PSU from Maplin that dropped all of 1 foot onto a floor and the two halves came apparently seemingly being glued in two little places, exposing the mains terminals of the transformer. I could go on, but really I think worrying about an older adaptor is not what you should be worrying about its the new stuff you need to watch for. My old torch had lasted over 10 years before it died, but many of the current wall warts seem to be good if they last three years. Never had a wall wart fail and I've got heaps of them and leave them plugged in all the time too. "Archibald Tarquin Blenkinsopp" wrote in message ... On Sat, 2 Feb 2019 12:53:20 -0000, "Andrew Mawson" wrote: "Scott" wrote in message ... I have a surge protection extension in the kitchen, used for TV, decoder box and radio. It is very old. I read here recently that these devices may present a fire risk. To my knowledge we have never had any surges or spikes. Should I be ditching this device? You will had had thousands of spikes. Every time your 'fridge compressor starts you'll get a detectable spike. Whether they are of significant magnitude is the question. The MOVs in surge suppressors do have a finite capacity for absorbing spike energy, and at end of life can go s/c so always should have a fuse in line, but in an extension it presumably is via a fused plug Andrew The MOV's are VDR's, and as long as they are not called on to dissipate more than their rating, they will work forever. They are simply a Voltage dependent resistor. They have an infinite lifespan if not overloaded. The vertical oscillator/ output stage in old valve TV's used them on the triode feed from the boost rail, specifically to stabilise the Voltage. These never, ever failed. There was one more in the frame stage, the thing would be across the primary of the field output transformer. This handled spikes, lots of them, 25 per second. They never failed either. VDR's or MOV's do not simply fill up with spikes and fail in their twilight years. They are a Voltage dependent resistor and whereas your 10K is always 10K whether it has one or ten Volts across it, a VDR is what it say's, "Voltage dependent". AB AB |
Surge protection
On Sunday, 3 February 2019 08:50:05 UTC, Brian Gaff wrote:
No no fuse just a resistor across the pins to discharge any charge left when you unplugged it. It is perfectly possible for a wall-wart containing a mains transformer to have no fuse but still comply with the relevant safety standards. For this to be the case the transformer itself must be rated to have an acceptable temperature rise when its output is shorted. John |
Surge protection
On Sunday, 3 February 2019 11:00:03 UTC, Archibald Tarquin Blenkinsopp wrote:
The CE mark has become a "CCCe" mark. "Chinese Copied Ce" perhaps ? Not quite. It is the certification required for selling products in China. The standards are very similar to CE however, with just enough difference to add some friction to trade. www.china-certification.com/en/ John |
Surge protection
On Monday, 4 February 2019 18:04:34 UTC, alan_m wrote:
On 04/02/2019 15:05, wrote: On Sunday, 3 February 2019 11:00:03 UTC, Archibald Tarquin Blenkinsopp wrote: The CE mark has become a "CCCe" mark. "Chinese Copied Ce" perhaps ? Not quite. It is the certification required for selling products in China. The standards are very similar to CE however, with just enough difference to add some friction to trade. www.china-certification.com/en/ John It's very clear that many items on Ebay from China costing a couple of quid (incl postage) and have a CE mark have never been near any certification process. True enough. However, the Chinese are very strict about certification of products exported from Europe to China, hence the requirement for CCC marking on such goods. In other words, you would not be allowed to re-import many Chinese electronic products sold in Europe back into China. I have also seen Chinese power supplies sold by a reputable UK supplier where the internal design changed substantially from one batch to the next without any evidence of re-certification. There was no change in part number. One automotive USB charger I looked at had conducted emissions more than 20dB above the allowed limit. It had component footprints for filtering capacitors on the pcb but they had not actually been fitted. This was bought from a major UK supermarket. The first batch of samples might well have been certified and then subsequent production "cost reduced". The savings would have been one or two pence in a product sold for around £10 at the time. John |
Surge protection
On 02/02/2019 11:10, Scott wrote:
I have a surge protection extension in the kitchen, used for TV, decoder box and radio. It is very old. I read here recently that these devices may present a fire risk. To my knowledge we have never had any surges or spikes. Should I be ditching this device? That fire risk was related to the story of surge supressors being used on a boat, where electrics could be done different - earth found floating halfway between live and neutral, that would place a constant voltage across the device, and a constant source of heat (and risk). Inland it is not a worry - heat only occurs when a surge is absorbed. -- Adrian C |
Surge protection
On Tue, 5 Feb 2019 11:30:14 +0000, Adrian Caspersz
wrote: On 02/02/2019 11:10, Scott wrote: I have a surge protection extension in the kitchen, used for TV, decoder box and radio. It is very old. I read here recently that these devices may present a fire risk. To my knowledge we have never had any surges or spikes. Should I be ditching this device? That fire risk was related to the story of surge supressors being used on a boat, where electrics could be done different - earth found floating halfway between live and neutral, that would place a constant voltage across the device, and a constant source of heat (and risk). Inland it is not a worry - heat only occurs when a surge is absorbed. Okay, thanks. This reassures me. The storyline was indeed on ship. I didn't know about the earthing situation there. I remember as a child being told that ship's equipment never worked on shore because of superstition. However, I fairly soon found out it was not because of superstition but because if was DC. |
Surge protection
On Tuesday, 5 February 2019 11:30:17 UTC, Adrian Caspersz wrote:
On 02/02/2019 11:10, Scott wrote: I have a surge protection extension in the kitchen, used for TV, decoder box and radio. It is very old. I read here recently that these devices may present a fire risk. To my knowledge we have never had any surges or spikes. Should I be ditching this device? That fire risk was related to the story of surge supressors being used on a boat, where electrics could be done different - earth found floating halfway between live and neutral, that would place a constant voltage across the device, and a constant source of heat (and risk). Inland it is not a worry - heat only occurs when a surge is absorbed. bzzzt. |
Surge protection
On Tuesday, 5 February 2019 11:30:17 UTC, Adrian Caspersz wrote:
That fire risk was related to the story of surge supressors being used on a boat, where electrics could be done different - earth found floating halfway between live and neutral, that would place a constant voltage across the device, and a constant source of heat (and risk). Inland it is not a worry - heat only occurs when a surge is absorbed. Why would having the earth floating between live and neutral be worse than the usual "inland" situation where one or other of the common mode surge suppressors will usually have the full mains voltage across it? It should make no difference at all for suppressors between live and neutral. John |
Surge protection
On 05/02/2019 14:57, wrote:
On Tuesday, 5 February 2019 11:30:17 UTC, Adrian Caspersz wrote: That fire risk was related to the story of surge supressors being used on a boat, where electrics could be done different - earth found floating halfway between live and neutral, that would place a constant voltage across the device, and a constant source of heat (and risk). Inland it is not a worry - heat only occurs when a surge is absorbed. Why would having the earth floating between live and neutral be worse than the usual "inland" situation where one or other of the common mode surge suppressors will usually have the full mains voltage across it? It should make no difference at all for suppressors between live and neutral. John Some types are wired delta, and the working voltage rating of the part connected neutral to ground *might* be low (expected inland, but not on a boat) https://www.littelfuse.com/~/media/e...ation_note.pdf Perhaps. I don't pretend to understand US coastguard paranoia, particularity where I can't find an authoritative statement exactly why they must have the precaution in place. So the above is mine. YMMV. Meanwhile, I'll offer US travellers a conversion service for their onboard electrical devices. $100 a snip ;- -- Adrian C |
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