Author Topic: The master switch of my hostel trips every time an incandescent lamp arcs  (Read 2624 times)
dor123
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The master switch of my hostel trips every time an incandescent lamp arcs « on: August 11, 2010, 04:46:20 AM » Author: dor123
I have found that every time when an incandescent lamp in my hostel turns into an arc lamp at its EOL, a very loudly BOOM sound shocking the environment of the arcing lamp (Even if the arcing lamp itself don't explodes) and the master switch of my hostel trips.
Why this is happens?
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I lives in Israel, which is a 220-240V, 50hz country.

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Re: The master switch of my hostel trips every time an incandescent lamp arcs « Reply #1 on: August 11, 2010, 05:53:18 AM » Author: SuperSix
I think it's because arcs have negative resistance so a very large amount of current is drawn which trips the switch. If the switch didn't trip then the light bulb, the fitting and electrical cables would overheat and pose a serious safety risk.

Most good bulbs should have internal fuses!
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dor123
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Re: The master switch of my hostel trips every time an incandescent lamp arcs « Reply #2 on: August 11, 2010, 07:16:28 AM » Author: dor123
Most of our incandescent lamps in my hostal are those chinese "LUXTEN" branded, and they are known as turning into an arc lamps at their EOL.
I don't know why the Israel Bureau of Standards allows for their markting. I think this is a first marks of the israeli black market for the incandescent lamps, when the incandescent lamps will be illegal in Israel.
Electric arcs are considered an electric short if they aren't current limited and as so the master switch trips when they develops.
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I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.

I only working with the international date format (dd.mm.yyyy).

I lives in Israel, which is a 220-240V, 50hz country.

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Re: The master switch of my hostel trips every time an incandescent lamp arcs « Reply #3 on: August 12, 2010, 03:54:18 PM » Author: Luminaire
I hear that its common in 230v power supply.  When the lamp breaks, eventually an arc forms between the filament supports creating a near dead short. 

If the source is able to supply enough current, the lamp can explode.  I believe I read a warning somewhere for 277v lamps meant for special application.  277v source fed from a three figure kVA 480/277 transformer has much higher fault current than a 120v outlet.
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Re: The master switch of my hostel trips every time an incandescent lamp arcs « Reply #4 on: August 12, 2010, 04:43:01 PM » Author: Medved
230V likes to form an arc, as it offer enough voltage to maintain current even in cold cathode mode (when lead-in wires become electrodes, after the filament evaporate). This then lead to sudden rise in current, what become limited only by the mains short circuit current.
So what happen next depend on the wiring impedance:
If you are living close to some bigger transformer, the impedance is low, so short current high, so the arc is able to build up enough energy to cause lamp explosion. Usually the circuit breaker die after ~10lamps due to the high stress during short current disconnection
If you are a bit farther away, the impedance is a bit higher, so such arcs only trip the breaker
If you are really far away (on the other village end then is the transformer), the impedance is so high, then usually the bulb just stop glowing, as the current is not high enough to transition to real arc (thermionic emission cathode) discharge.


Remark for those from US: Unlie in US (where each home has it's "own" transformer to supply it by single phase 2*120V GroundedCenterTap), 230V countries use one three phase transformer HV to 3*230/400 (230V is between each phase and grounded Neutral, 400V between two phases) rated in MW range, common for many homes (50..100 to sum up for such power), so the low voltage wiring from the transformer is often very long.
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Re: The master switch of my hostel trips every time an incandescent lamp arcs « Reply #5 on: August 13, 2010, 05:01:00 AM » Author: dor123
In my mother home, we experienced a problem in which our GE Hungary krypton filled mushroom incandescent lamps at their EOL, were cutted off from their bases in our inverted chandelier (Lamps pointing down) at the salon and falled to the carpet, while their E27 bases remained in the sockets.
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I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.

I only working with the international date format (dd.mm.yyyy).

I lives in Israel, which is a 220-240V, 50hz country.

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Re: The master switch of my hostel trips every time an incandescent lamp arcs « Reply #6 on: August 13, 2010, 01:56:56 PM » Author: Luminaire
230V likes to form an arc, as it offer enough voltage to maintain current even in cold cathode mode (when lead-in wires become electrodes, after the filament evaporate). This then lead to sudden rise in current, what become limited only by the mains short circuit current.
So what happen next depend on the wiring impedance:
If you are living close to some bigger transformer, the impedance is low, so short current high, so the arc is able to build up enough energy to cause lamp explosion. Usually the circuit breaker die after ~10lamps due to the high stress during short current disconnection
If you are a bit farther away, the impedance is a bit higher, so such arcs only trip the breaker
If you are really far away (on the other village end then is the transformer), the impedance is so high, then usually the bulb just stop glowing, as the current is not high enough to transition to real arc (thermionic emission cathode) discharge.


Remark for those from US: Unlie in US (where each home has it's "own" transformer to supply it by single phase 2*120V GroundedCenterTap), 230V countries use one three phase transformer HV to 3*230/400 (230V is between each phase and grounded Neutral, 400V between two phases) rated in MW range, common for many homes (50..100 to sum up for such power), so the low voltage wiring from the transformer is often very long.
I've read that lead wires are thinned down enough to function as a fuse. 

There isn't necessarily a transformer for each house in the U.S.  In a very rural area where its miles between neighbors, yes. 

Suburbs have shared transformer producing 120/240 split phase. 

Densely populated cities often have 208/120 and 480/277 underground grid.  Apartment complexes, hotels, dormitories have 208/120. 
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Re: The master switch of my hostel trips every time an incandescent lamp arcs « Reply #7 on: August 13, 2010, 05:45:16 PM » Author: Medved
I've read that lead wires are thinned down enough to function as a fuse. 

They are thinned, but to serve as real fuse they are missing arc extinguishing component (in real fuses this is the sand fill). Without such measure, even if the wire evaporate, the mains short current continues to flow trough the arc.

Fuses without the sand fill (cheapest glass ones; equivalent to the assembly in incandescent) have the current breaking capability (the maximum fault current they are able to interrupt within specified time) about 20A for 250VAC (OCV), what suffice only for overload protection of devices, what limit the current (e.g. low power transformer by at least the resistance of it's primary wuinding wire), but by far not for typical mains short circuity current (~500A when really far from the transformer; by far enough to maintain the arc).
If you look into e.g. better PC supply unit, you would find ceramic fuse, what use some sort of sand as arc extinguisher. Result is breaking capability above 1.5kA - just marginal for mains short circuity (they expect, then the short in the failed unit is not as hard to cause higher fault currents)
But for home fuses (or circuit breakers these days) the required breaking capability is at least 6kA, higher quality models start at 10kA (and some even feature fault curent limiters), as this is cosidered as safe minimum to properly handle even hard shorts. And this would have to be the capability of the fuse inside the incandescent to ensure, it will die really peacefully. But in such case the wire would have to be at least 5cm long and inside the sand fill (arc extinguisher).
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Re: The master switch of my hostel trips every time an incandescent lamp arcs « Reply #8 on: August 14, 2010, 11:20:00 PM » Author: xmaslightguy
Remark for those from US: Unlie in US (where each home has it's "own" transformer to supply it by single phase 2*120V GroundedCenterTap)

There isn't necessarily a transformer for each house in the U.S.  In a very rural area where its miles between neighbors, yes. 

In my area its around 10 houses to a transformer (which i believe is fairly common)... & wireing is underground.

------------------
Some cities/counties codes are now requiring "arc-fault" circuit breakers in homes on new construction.
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