Converting Dome Lights to G4 Halogen?

[Nigel S]

My boat has got conventional dome lights in the ceiling with 10w festoon bulbs and I'm thinking of changing to G4 halogen to get a bit more light especially in the saloon. Is there any easy way of converting the existing fittings rather than replacing them completely?

 

I see that it is possible to buy porcelain G4 lampholders from Maplin which presumably, could be mounted in the existing housings - does anyone have any comments?

 

Would it be worth completely replacing the fittings with similar looking 2D fluorescent types in terms of light output for the same wattage - and if so does anyone have any particular recommendations?

 

Thanks

 

Nigel

[chris w]

I love Maplins for a lot of stuff but they are generally significantly more expensive on items such as G4 lampholders etc as compared to ScrewFix and other similar places.

 

Chris

[DHutch]

I would just swap out the whole unit for one designed for halgoens, it wont cost that much.

- Also, bearing in mind most halogens use dicroic reflectors, make sure there is plently of clearence behind the fixture, ortherwise you could risk damaging/ignighting you insulation and/or fitout.

 

Also, if you after more light, i would also consider the use of florecent units.

 

 

Daniel

[David Schweizer]

My boat has got conventional dome lights in the ceiling with 10w festoon bulbs and I'm thinking of changing to G4 halogen to get a bit more light especially in the saloon. Is there any easy way of converting the existing fittings rather than replacing them completely?

 

I see that it is possible to buy porcelain G4 lampholders from Maplin which presumably, could be mounted in the existing housings - does anyone have any comments?

 

Would it be worth completely replacing the fittings with similar looking 2D fluorescent types in terms of light output for the same wattage - and if so does anyone have any particular recommendations?

 

Thanks

 

Nigel

I have converted most of the inverted dome ceiling lights on my boat from festoon bulb to halogen. I converted them with some cheap surface mounted low profile cabinet downlighters which use the G4 lamp. I discarded the outer casing and reflector and cut down the internal fitting, leaving the lamp holder and a flat tab behind the holder, this tab was drilled with a 3.2mm hole and a similar hole was drilled into the ceiling light reflector. The modified G4 lamp holder was pop riveted onto the ceiling reflector. The domed difuser on the ceiling light fitting gives more than sufficient clearance to prevent any overheating.

[Nigel S]

I have converted most of the inverted dome ceiling lights on my boat from festoon bulb to halogen. I converted them with some cheap surface mounted low profile cabinet downlighters which use the G4 lamp. I discarded the outer casing and reflector and cut down the internal fitting, leaving the lamp holder and a flat tab behind the holder, this tab was drilled with a 3.2mm hole and a similar hole was drilled into the ceiling light reflector. The modified G4 lamp holder was pop riveted onto the ceiling reflector. The domed difuser on the ceiling light fitting gives more than sufficient clearance to prevent any overheating.

 

Thanks David - that was the sort of thing I was thinking of, although my idea was to use a very small Maplin porcelain G4 lampholder base (I'm afraid I don't know whether this whole link will be reproduced):

 

http://www.maplin.co.uk/Search.aspx?criter...rce=15&SD=Y

 

This seems to have two small fixing holes. Are your bulbs just pointing straight down or did you arrange them to be horizontal (which might be more secure - I was thinking that vibration of the boat might shake them loose otherwise)?

 

I certainly don't see that overheating should be an issue - the G4 capsules are very small and if they are the same wattage as the festoon bulbs but more efficient, the wasted heat ought to be less if anything. Anyway, I assume you got a worthwhile improvement in light output?

 

Nigel

[Theo]

Thanks David - that was the sort of thing I was thinking of, although my idea was to use a very small Maplin porcelain G4 lampholder base (I'm afraid I don't know whether this whole link will be reproduced):

 

http://www.maplin.co.uk/Search.aspx?criter...rce=15&SD=Y

 

This seems to have two small fixing holes. Are your bulbs just pointing straight down or did you arrange them to be horizontal (which might be more secure - I was thinking that vibration of the boat might shake them loose otherwise)?

 

I certainly don't see that overheating should be an issue - the G4 capsules are very small and if they are the same wattage as the festoon bulbs but more efficient, the wasted heat ought to be less if anything. Anyway, I assume you got a worthwhile improvement in light output?

 

Nigel

 

Since the bulbs are much smaller would there be a danger of a high temperature spot even though they are more efficient? We have ultra cheap halogens and have just had to replace a number of the shades. The bulb had dangled to close to them and had melted holes in them.

 

Nick

[Nigel S]

Since the bulbs are much smaller would there be a danger of a high temperature spot even though they are more efficient? We have ultra cheap halogens and have just had to replace a number of the shades. The bulb had dangled to close to them and had melted holes in them.

 

Nick

 

Nick:

 

I certainly don't like the sound of them "dangling" on a boat! What I am suggesting is that the G4 bulb will be securely fixed on a ceramic base inside a standard kind of dome light with the filament in virtually the same position as the original festoon bulb - i.e mounted onto the metal base and well clear of the inside of the shade (which is glass anyway).

 

You're quite right, the local temperature adjacent a halogen bulb is probably very high which means you don't want to have any thermoplastics nearby, but the total amount of heat (i.e inside the glass shade) certainly shouldn't be more than generated by the festoon bulb. Also I'm not talking about reflector lamps here which focus the light - eg. MR16 spots - but rather the small G4 bare quartz capsules which are not much different in size to a standard festoon bulb.

 

If reflector lamps were a consideration I think it would definitely be safer to change the whole fitting.

 

Nigel

[Serendipity]

I asked this question a few months back, as I didn't want to lose my dome lights and thought there must be adapters available. I did locate adapters, but only on an American site.

 

In the end I bought a set of replacement bulbs from canalshopman. These are simply the old style bulb, with a halogen capsule embedded in them.

[David Schweizer]

Nigel. The bulbs in my converted lights are horizontal (that is how they are fixed in the cabinet downlighters)

 

As far as heat is concerned, my ceiling lights comprise of an aluminium pressing aproximately 6" diameter, with the concave base of the lamp serving as the reflector, this is more than adequate as a heat sink, in fact several of my conversions are fitted with 20w lamps with no over heating problems.

 

If I remember to take my camera when I next visit my boat, I will try and take a couple of pictures and send them to you.

[wrigglefingers]

I'm just starting to change my individually switched domes for halogen lamps from Midland chandlers. I tried to swap the lights for inset halogens but ran into problems trying to add a switch to the circuit; everything I tried simply looked like a bodge job and switched insets don't seem to exist. In the end it just proved less hasslesome to buy a whole new unit; although at a swingeing cost (17.95 per unit and I have to replace 10 eventually as the brass one seem to be in very short supply). The units are reading type lamps using a 10W bulb, the initial one in place doesn't seem to cause a hot spot on the ceiling as it has a 3 inch tube from ceiling fitting to lamp holder. After a winter in partial gloom it's revolutionised my space for sewing as I can now see to do it rather than guess and stitch.

 

Shep

[magnetman]

These might have switches on them, don't know but I've seen similar ones which are switched in the chandleries but silly money:

 

http://cgi.ebay.co.uk/4-x-12v-halogen-down...bayphotohosting

[John Orentas]

There is a vast range of G4 tungsten halogen lamps manufactured, they vary not only in wattage but in lamplife, filament alignment and other ways too. When retro-fitting TH lamps with plain or square type filaments make sure you align the filaments with the large flat side towards the reflector, you will get more light output that way.

 

When buying complete down-lighters go to a B & Q type place they will be half the price of a chandler and take a good look at the box, if sold as 'display lights' the are likely to be fitted with high output, short life lamps some as low as 200 hours. Remember too the lamp/reflector units are made with differing beam divergences, go for the broadest 45 deg spread.

Edited February 26, 2007 by John Orentas

[chris w]

Screwfix have brass or chrome 12v halogen downlighters for as little as £1.10 each see here

 

Chris

[wrigglefingers]

Okay, progress report so far ......

 

I've replaced three out of the four lights I bought at great expense, as here

 

The fourth is faulty, hmmm. I can tell you that the units are so hot I can't touch them after 10 minutes on and that includes the fitting area. I'm currently checking whether they are going to scorch the wood of my ceiling or whether I'll need to put in a fire collar or similar! Any suggestions?

[Nigel S]

Screwfix have brass or chrome 12v halogen downlighters for as little as £1.10 each see here

 

Chris

 

Thanks for the suggestion, Chris - I'm a great Screwfix fan as well but the trouble with most of the very cheap downlighter fittings is that they don't have switches so you have to do extra wiring and also they are intended for MR16 reflector lamps which have a minimum wattage of 20w (as far as I know - does anyone know of a 10w version?). I don't really want to go to 20w unless the light from the 10w lamps is still not good enough, and in any case I'm not really looking for a "spotlight" effect. You can also get G4 capsules in all sorts of low wattages - 5,10,15,20 etc.

 

In order to avoid the switch problem (and to keep the reasonably "boaty" light fittings I've already got) I'm really trying to build something into the existing domes as David S has done, so I'd rather use bare lamp bases which are more likely to fit inside - which I don't think a reflector lamp/downlighter arrangement will do.

 

Of course Screwfix also do "cabinet downlights" (£3.52) which take G4 capsules, the reflectors being built into the fitting rather than being built into the lamp, which might fit inside but it looks as though it could be a bit tight so one might well have to take them apart. Consequently I think I'll try one bare Maplin lampholder (£2.99) before buying lots more bits!

 

Nigel

[smileypete]

Okay, progress report so far ......

 

I've replaced three out of the four lights I bought at great expense, as here

 

The fourth is faulty, hmmm. I can tell you that the units are so hot I can't touch them after 10 minutes on and that includes the fitting area. I'm currently checking whether they are going to scorch the wood of my ceiling or whether I'll need to put in a fire collar or similar! Any suggestions?

 

Hi,

 

What sort of bulbs do they use, ones with a built in reflector? MR11/16 eg:

 

 

cheers,

Pete.

[wrigglefingers]

Hi,

 

What sort of bulbs do they use, ones with a built in reflector? MR11/16 eg:

 

 

cheers,

Pete.

 

Yup, MR 16s, so not the 10W either. I've checked the temperature and incandescent just about describes the temperature. No scorch marks though, but i've had an idea. I use heat retardent wadding when I make bed quilts so I'll check the temperature range on that tomorrow at school to see whether I can use it as a heat baffle next to the wood.

 

Jill

[smileypete]

Yup, MR 16s, so not the 10W either. I've checked the temperature and incandescent just about describes the temperature. No scorch marks though, but i've had an idea. I use heat retardent wadding when I make bed quilts so I'll check the temperature range on that tomorrow at school to see whether I can use it as a heat baffle next to the wood.

 

Jill

 

Hi,

 

Sounds like you might have bulbs with 'dichroic' reflectors. These reflect the light forward, but allow nearly all the heat straight back through the reflector.

 

They are meant for display lighting heat sensitive stuff with unenclosed lights. In an enclosed light they are bad news as all the heat builds up in the back of the light!

 

What would be better is bulbs with aluminium reflectors, that reflect nearly all the heat forwards, eg:

 

http://www.screwfix.com/app/sfd/cat/pro.js...59&id=28198

http://cgi.ebay.co.uk/10-x-MR16-20w-12V-lo...1QQcmdZViewItem

 

or a local electrical wholesaler or place like B&Q should have them.

 

cheers,

Pete.

[DHutch]

Yeah, alu ones are clearly the way fwd for boats.

- Shoudl have mentioned that when i said that most are dicoric.

 

Dichroic is such a cool word...

 

 

Daniel

[KenK]

You could try these two websites.

 

www.ebulbshop.com They do have 10 watt MR16 lamps although fairly narrow output

 

or

 

www.ricamstore.co.uk They do MR16 lamps with "cool back" reflectors not in 10 watt though, minimum 20 watt

 

Usual disclaimer

 

Ken