Appleyard
Well-Known Member
It's definitely not vibration..there is nothing above the ceiling except an attic. So far lots of ideas ,thanks to all.
Any sparkies here?( non boaty)
- Thread starter Appleyard
- Start date
starboard
Well-Known Member
how about replacing them with low voltage type.......these LV halogen bulbs can last about 10 times longer than 240v equivalent and are easy enough to fit, most come with transformer attatched.
Paul.
Paul.
Appleyard
Well-Known Member
I replaced the low voltage types with mains voltage as they were not lasting!! and yes the wiring was correct.
starboard
Well-Known Member
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I replaced the low voltage types with mains voltage as they were not lasting!! and yes the wiring was correct.
[/ QUOTE ]
Ok then suggest Parafin Lamps, these should do the trick!
Paul.
I replaced the low voltage types with mains voltage as they were not lasting!! and yes the wiring was correct.
[/ QUOTE ]
Ok then suggest Parafin Lamps, these should do the trick!
Paul.
peterb
Well-Known Member
[ QUOTE ]
If any surge was causing a problem I think it would be from switching them off. Much bigger dv/dt.
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The usual problem with bulb breakage is non-uniform heating of the filament. The resistance of most metals (including tungsten) increases with temperature. When the bulb is first switched on its resistance is low, and there is an initial current surge. If one part of the filament heats more quickly than the rest, then the resistance of that part will increase while the initial current surge is still there. This causes the temperature of that part to go up still further, and for a short time that part will be even hotter than its normal running temperature. So much so that some of the tungsten will evaporate leaving that part a little thinner than the rest of the filament. The thinner filament has a higher resistance, so next time you switch on it will get even hotter, and so on until the filament breaks.
Using a soft-start dimmer control enables the filament to heat up more uniformly, thus reducing the problem. Just be careful about using dimmers with transformer-fed low voltage bulbs; not all dimmers and transformers will work together.
You can get a similar result by putting an NTC thermistor in series with the bulb. This has an initial high resistance, but then as it warms up its resistance drops rapidly so that in normal operation the bulb sees virtually full voltage.
If any surge was causing a problem I think it would be from switching them off. Much bigger dv/dt.
[/ QUOTE ]
The usual problem with bulb breakage is non-uniform heating of the filament. The resistance of most metals (including tungsten) increases with temperature. When the bulb is first switched on its resistance is low, and there is an initial current surge. If one part of the filament heats more quickly than the rest, then the resistance of that part will increase while the initial current surge is still there. This causes the temperature of that part to go up still further, and for a short time that part will be even hotter than its normal running temperature. So much so that some of the tungsten will evaporate leaving that part a little thinner than the rest of the filament. The thinner filament has a higher resistance, so next time you switch on it will get even hotter, and so on until the filament breaks.
Using a soft-start dimmer control enables the filament to heat up more uniformly, thus reducing the problem. Just be careful about using dimmers with transformer-fed low voltage bulbs; not all dimmers and transformers will work together.
You can get a similar result by putting an NTC thermistor in series with the bulb. This has an initial high resistance, but then as it warms up its resistance drops rapidly so that in normal operation the bulb sees virtually full voltage.
Sixpence
Well-Known Member
[ QUOTE ]
Trust me I am a sparkie!
CEF i consider the Woolworths of the electrical wholesale business....usually selling cheaper versions of stuff at regular prices.
Try a "soft start" dimmer..MK for example. Dont think CEF sell MK....
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Head
Brick wall
Lots of banging
Join the club
I'm ( almost ) a complete novice sailor , and I tend to look for advice on boats from people that , erm , know boats , so why don't those that know about boats listen to those that know about electrics ? , beats me every time and I get slated for not trying to help out , you can't win so give up it saves a lot of worry because most people have dangerous installations because they asked for advice down the pub and it sounded better than what the sparkie told them
Trust me I am a sparkie!
CEF i consider the Woolworths of the electrical wholesale business....usually selling cheaper versions of stuff at regular prices.
Try a "soft start" dimmer..MK for example. Dont think CEF sell MK....
[/ QUOTE ]
Head
Brick wall
Lots of banging
Join the club
I'm ( almost ) a complete novice sailor , and I tend to look for advice on boats from people that , erm , know boats , so why don't those that know about boats listen to those that know about electrics ? , beats me every time and I get slated for not trying to help out , you can't win so give up it saves a lot of worry because most people have dangerous installations because they asked for advice down the pub and it sounded better than what the sparkie told them