Blown Bulb in Lamp - burn marks - is lamp safe to re-use?

waterwatereverywhere

Hi,

Hope someone can help.

A bedside lamp blew loudly the other day when switched on from cold and it caused the fuse at the mains board to pop.

I took out the bulb and noted that it is 60W but the lamp states 40W max - don't know how this happened, must have bought/used the wrong wattage by mistake - although the lamp has been working like this for months.

The bulb is a screw in (SES E14) and on the metal screw in part of the bulb there are black marks and holes where it looks like it has completely overheated.

Would it be safe to buy the correct 40W bulb and re-try or might the lamp itself have been damage beyond repair as a result of this. Frightened to try.... - is the worst that can happen that it would just immediately blow the fuse again?

Many thx in advance for any help on this.

Ruski

Try a new bulb, I doubt the light fitting itself is at fault.


The 40w max refers to the max recommended bulb for the lampshade, not the fitting itself.


HTH


Russ

Norman_Castle

If there are burn marks and signs of overheating I would be wary of using it again. If it tripped the fuse this may be from a short and is unlikely to be caused just from a bulb failing.

Southend1

Also I would look at LED alternatives as 40 or 60w bulbs are very inefficient. The equivalent LED would be 5-7w

Ben84

You're right that you shouldn't be using a 60w bulb in this lamp if the label says 40w. Lampshades are rated for maximum wattages, but so are the lamps themselves as they too have labels. You should not exceed the lowest of the two. However, I doubt this was the cause of your problem as I've never known lamps with the wrong bulb do this. Usually they just get a bit cooked and the plastic around the bulb yellows and goes brittle. They don't go bang, blow fuses or eat holes in metal, so I suspect your bulb or the lamp's wiring might have been making poor contact with the bulb holder and started arcing. This generates a lot of heat and can damage metal, so it's likely your lamp's bulb holder is damaged too. I'd get it checked out before using it again. Perhaps a local electrical shop can help? Lamps are easy enough to repair in most cases as you can replace the bulb holder and/or wiring quite readily.

As for bulbs, you could benefit from using the new style halogen bulbs. They come in the same shapes, sizes and bases as the old bulbs, but because they're halogen they use about 1/3rd less electricity to make the same light, and also make about 1/3rd less heat so they're better for your light fixtures. They also last twice as long.

brightontraveller

If lamp holder has not been damaged become brittle etc replace with retrofit Led 5w ses14 choose dimmable or not give you same lux/light output (maybe more than 40w) they have generally a 25k hrs life span dependant on manufacture will set you back £5 -10 these stay cool to touch

As opposed to 1k hrs on 40W ses14 £2 -3 get reasonable hot or 2k hrs on halogen type ses14 £3 -4 get hot as the sun. 10k hrs on CFL 7w ses14 £5 -8 can get warmish

Ben84

brightontraveller wrote: »

If lamp holder has not been damaged become brittle etc replace with retrofit Led 5w ses14 choose dimmable or not give you same lux/light output (maybe more than 40w) they have generally a 25k hrs life span dependant on manufacture will set you back £5 -10 these stay cool to touch

As opposed to 1k hrs on 40W ses14 £2 -3 get reasonable hot or 2k hrs on halogen type ses14 £3 -4 get hot as the sun. 10k hrs on CFL 7w ses14 £5 -8 can get warmish

A halogen replacement for the 40w incandescent would be about 28w - so this is a fair bit cooler running than the 40w bulb.

brightontraveller

Ben84 wrote: »

A halogen replacement for the 40w incandescent would be about 28w - so this is a fair bit cooler running than the 40w bulb.

Halogen lights work in a very similar way to standard incandescent bulbs. In fact, they are essentially an extension of incandescent design
With a few differences ...

A tungsten filament sits at the heart of both but the halogen bulb is surrounded by a quartz envelope which contains within it a halogen gas. When its powered up the filament begins to glow on a standard tungsten filament having no gas or reaction to the gas around it means it will be cooler but lose its ability to glow much quicker the presence of the gas creates a reaction which takes the tungsten vapour and re-coats the filament with it. Within a halogen bulb this reaction causes heat along with the filament so it gets hotter than the standard incandescent wattage is irrelevant ...

So a poor choice in the instant as described when alternatives are available with longer running times lower energy consumption miniscule initail outlay cost

Ben84

brightontraveller wrote: »

Within a halogen bulb this reaction causes heat along with the filament so it gets hotter than the standard incandescent wattage is irrelevant ...

That's not how it works. The filament is higher temperature, but the bulb itself is still emitting less heat energy total. You're confusing heat with temperature.

Heat is total amount of energy, temperature is a property of heat energy and mass. Put more heat energy in to a smaller amount of mass and the item's temperature goes up.

The halogen bulb has a thinner filament, so it's a higher temperature for the same energy input. This makes it glow brighter and emit more light at the same wattage as a thicker filament regular bulb.

What tends to happen however is halogen bulbs are made in lower wattages so that their light output matches regular bulbs we're used to. So, a halogen 28w replaces a regular 40w. Although it's interesting, we don't really need to worry about the goings on inside the bulb or what temperature the filament is, because it's bulb shaped and a fraction less than 28w of total heat energy is going to be emitted by its surface. So, it's cooler running than another same shape and size bulb emitting a fraction less than 40w heat energy.

Try it for yourself if you have examples of these bulbs around your house, the 28w GLS halogen can be touched briefly even after running for hours. The 40w bulb will promptly burn you if you try to touch it when it's been on for a few minutes or more.