Bulb melted socket after installing dimmer switch

M

mjgreen81

Joined
5 Oct 2014
Messages
124
Reaction score
5
Location
Hertfordshire
Country
United Kingdom
Hi all,

I have a plain and simple 100w max light fitting in a spare room. I am just about to renovate it to be a nursery so thought it would be a good time to install a dimmer switch.

The fitting originally had a 100w bulb which I found hummed a lot. After some googling I found this was not unusual and could be resolved by using a lower watt bulb or by trying a 'rough service' bulb that has a thicker filament and less prone to vibration which makes the humming.

After some hunting around the house I found a 60w rough service bulb and gave this a try. It resolved the humming perfectly, but I found it to be a bit dreary in the room so wanted to try a 100w rough service bulb.

I order a 100w rough service bulb and just tried it and although there was a little bit of humming at certain levels of dimness, it was much better. However, after 5 minutes or so I could smell burning and noticed that the bulb had actually partially melted the plastic on the light fitting.

I did notice that the new 100w bulb did seem exceptionally bright. I am sure it was brighter than the previous non rough service 100w bulb I had before installing the dimmer switch.

What is going on here? Did I get a bad bulb? Or is the dimmer switch not compatible and is somehow suppling more power than it is supposed to?

Thanks
 
fault bulb.
or poor contacts on the holder and/or bulb I think. make sure they are shiny before starting again
 
Yeah, that's not a huge problem. I only bought a cheap dimmer switch so don't mind replacing it.

I am going down a bit of a wormhole looking at my options. I see that some of these LED units come with thier own remote control allowing you to dim, change colour etc. I had no idea there were so many options!
 
mjgreen81 said:
Or is the dimmer switch not compatible and is somehow suppling more power than it is supposed to?
Click to expand...

The dimmer switch can't do this, but one of your other comments :

mjgreen81 said:
I did notice that the new 100w bulb did seem exceptionally bright. I am sure it was brighter than the previous non rough service 100w bulb I had before
Click to expand...

Rough service lamps are usually dimmer than their non-rough service friends... any chance you may have purchased a 110V lamp????

That would explain everything!
 
AdrianUK said:
The dimmer switch can't do this, but one of your other comments :



Rough service lamps are usually dimmer than their non-rough service friends... any chance you may have purchased a 110V lamp????

That would explain everything!
Click to expand...

It's a 100w/110v lamp.

I thought that as long as it is 100w (which is the max for the fitting) I would be Ok?
 
mjgreen81 said:
It's a 100w/110v lamp.

I thought that as long as it is 100w (which is the max for the fitting) I would be Ok?
Click to expand...

Don’t do any more DIY electrics until your knowledge is massively improved.
 
Ok crap, I just read up and have learned something new.

Can't believe I have gone this long without understanding the significance of the voltage rating on a lamp.

Embarrassing

I guess I have just always picked up a bulb from the shop which are always standard 240v. Now they are quite hard to get hold off I didn't check this.

Lesson learned
 
mjgreen81 said:
It's a 100w/110v lamp.

I thought that as long as it is 100w (which is the max for the fitting) I would be Ok?
Click to expand...

Ah, now everything makes sense!

No. A 110V lamp is not suitable for direction connection to the UK mains. The UK mains is 230V. As a result the lamp would have seen a voltage much higher than designed, in fact operating at approx twice its design voltage would mean it drew around 4 times the power... it would be more like a 400W lamp. Hence why you observed it to be very bright & very hot.

This lamp is really intended for a building site which uses 110V lighting for safety.
 
AdrianUK said:
Ah, now everything makes sense!

No. A 110V lamp is not suitable for direction connection to the UK mains. The UK mains is 230V. As a result the lamp would have seen a voltage much higher than designed, in fact operating at approx twice its design voltage would mean it drew around 4 times the power... it would be more like a 400W lamp. Hence why you observed it to be very bright & very hot.

This lamp is really intended for a building site which uses 110V lighting for safety.
Click to expand...

*Cringe* Thanks again
 
mjgreen81 said:
It's a 100w/110v lamp.

I thought that as long as it is 100w (which is the max for the fitting) I would be Ok?
Click to expand...
No I'm afraid not, it doesn't work that way.
A 110v 100W bulb will be running at about 440W or in round terms more than 4 times as bright.
The average fan heater will be around 2000W to 2500W so the amount of heat given off by your bulb is somewhere 1/6th to 1/4 of a room heater, so yes it will be very hot and cause a lot of heat damage.

On top of this rough service bulbs tend to be a yellower light and not as bright, accordingly the reduction of light output means some other form of output and this will be in the form of heat. In other words a rough service bulb is usually hotter than an equivalent standard bulb.

EDIT:
I started writing this reply just after message #9 was posted and didn't see the next 4 before posting.
 
If this hadn't been a rough service bulb, chances are it would have blown quite quickly, possibly instantly.
 
One firm I worked at kept the 110V and 230V 500W halogen lamps next to each other in the stores. I think everyone who worked there at some point grabbed the wrong voltage lamp and put it in a 230V fitting.

It went with quite a bang when I did it :LOL:
 
You must log in or register to reply here.
Back
Top