I don't have any details of the situation, so I'm just looking for a ballpark, well-in-theory, kind of answer.
I had a tenant say that her TV was "destroyed" (I don't know what that means exactly) and that the fire department said that it was "bad wiring" in the house, and that we need to bring in an electrician to fix it. It's perfectly plausible that the wiring is bad - it's an old house, and the previous owner did DIY work on the wiring and messed a few things up.
So I'm wondering how would "bad wiring" cause a TV to get destroyed? I've never heard of this before.
On Jan 17, 12:21=A0pm, swansnow wrote: > I don't have any details of the situation, so I'm just looking for a > ballpark, well-in-theory, kind of answer. >
Yep, it can happen. The scenario would be a poor neutral connection so that a 120 volt on one 'phase' may be significantly higher or lower than the 120 while the 240 to the oven or AC unit is fine.
Yep, it can happen. The scenario would be a poor neutral connection so that a 120 volt on one 'phase' may be significantly higher or lower than the 120 while the 240 to the oven or AC unit is fine.
To elaborate on that a little: If the neutral is open (doesn't go to the center tap of the transformer serving the house), then you have 240 volts across two of your circuits which are in series with each other. As long as the two circuits have about the same load on them, each will get about 120 volts. But if one circuit gets a much heavier load (e.g., air conditioner), the other circuit gets appreciably more than 120 volts.
Also if DIY work has been done, there's no telling what could be the case. A
120V branch circuit or receptacle wired to 240V can certainly do this, though it's usually quickly obvious something is wrong. Yes, I've seen it done. If only newbies insisting on doing their own work would at least pick up a DIY book first.
:>> So I'm wondering how would "bad wiring" cause a TV to get destroyed? :>> I've never heard of this before. :>
:> Defective neutral bonding will do this. : :To elaborate on that a little: If the neutral is open (doesn't go to the :center tap of the transformer serving the house), then you have 240 volts :across two of your circuits which are in series with each other. As long as :the two circuits have about the same load on them, each will get about 120 :volts. But if one circuit gets a much heavier load (e.g., air conditioner), :the other circuit gets appreciably more than 120 volts. :
When I read such anecdotes as related in this thread it makes me thankful we have a single domestic supply voltage for GPO's in Australian homes (240V single phase MEN system).
not only the wiring - i have seen tvs damaged by being plugged into loose sloppy fitting mains socket adaptors. the resulting coming and going of the power not only produced arcing at the plug but stressed the TV switch mode power supply.
The one I am familar with is a clock radio and a toaster on a shared neutral circuit in the kitchen. Mother was telling me that the radio would only come on when the toaster was on. When she showed me smoke came out the back of the radio.
On Jan 17, 6:14=A0pm, Ross Herbert wrote: > :To elaborate on that a little: =A0If the neutral is open (doesn't go to the > :center tap of the transformer serving the house), then you have
240 volts > :across two of your circuits which are in series with each other. =A0As long as > :the two circuits have about the same load on them, each will get about 120 > :volts. =A0But if one circuit gets a much heavier load (e.g., air conditioner), > :the other circuit gets appreciably more than 120 volts. > : >
Please remember there are over 200 million structures in the US wired this way. The fact that the TV failure is 'news' shows how infrequently it happens. If neutral issues happened enough, rules would change because insurance rates would go up. Capitalism would take care of the problem.
Better get my fire extinguisher ready as I fear I've started a flame war.
The voltage on the outlet the TV was plugged into could be too low, too high or fluctuating often and causing stress to the TV's circuitry.
The outlet itself could have been wired improperly, such that it was carrying a voltage that was totally inappropriate for the TV set. It is possible to wire a 110 volt outlet (where 110/120 volt power is used) to have 220/240 volts coming to it. The results from this would be immediate and probably catastrophic, so if the TV did not fail immediately, this is probably not the cause.
Finally, as another poster mentioned, there could be a poor neutral connection somewhere in the wiring. If this were the case, the two "legs" of
110/120 volts AC will not be balanced and the voltage on each one will fluctuate wildly as loads come and go.
Have you determined exactly what constitutes "destroyed?" I found out the hard way in the 90s that the near-ubiquitous RCA motherboards had grounding issues with the front-end can. Research (here among other places) revealed that lousy soldering on the shield could cause the main chip to lose its programming, resulting in an otherwise perfect TV being useless. I could see that being triggered by power/grounding issues. My problems started with a building-wide fire alarm going off, perhaps coincidental.
IMHO: Sounds the the Landlord should have the set professionally inspected, paying the estimate (service) fees, to absolutely determine what may have actually caused the problem. (Not to pay for repairing the set unless definative proof of fault is presented.)
I once got several home appliances in for an insurance estimate from a house that the 'ground' from the 240 was lifted as a result from an auto/pole accident.
The moon is yellow. Therefore a tornado will hit Brazil. IOW they did not say what is defective or why - so we know near nothing.
The defective nuetral wire problem could cause TV damage by raising voltage excessively. Is that happenening? We always need facts such as incandescant lamps brightening or dimming when a major load is applied or disconnected.
Other problems such as loose wiring would not damage any properly constructed electronics. And this stated bluntly in direct contradiction to a popular myth. If bad wiring caused TV damage, then wiring must cause voltage to be excessive - not low. And then incandescant bulbs are also failing prematurely.
Meanwhile, if the fire department identified a wiring problem, well, that may only be another problem completely independent of TV failure. That report of wiring failure from fire people means an electrician is required to inspect and provide an estimate.
Disagree, arcing in a mains socket can cause smps blow-ups. a common cause of psu failure in the Amstrad/Sky satellite receiver which is popular over here is a poor connection in the figure eight mains connector.
You may argue that said receiver isn't properly constructed, but there are tens of thousands in service, and it has passed the current strict European regulations
European regulations do not say a SMPS (or any appliance) need be properly designed. Those standards address limited design issues such as human safety threats, EMI, harmonics, etc. None address all reliability issues. Although EMI circuits would make an appliance even more resistant to line arcing, still, other internal design defects may let that unit be harmed by power wire arcing.
Some early Tivos also met regulations and yet suffered internal failures. Damage created by something that should never have caused that damage. Regulations do not address reliability. If line arcing causes appliance failure, then a defect exists in that appliance design.
Excessive voltage would harm an appliance. Any 'bad wiring' that could destroy the TV must cause excessive voltage. That voltage typically would be made obvious by incandescent bulbs changing intensity or failing prematurely. Any SMPS harmed by something trivial like an arcing plug is defectively designed (and can still conform to European regulations).
Again, firemen cited a 'wiring problem'. Without specific technical details, that means an electrician is required.
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