240 light output conversion to 12v

[Kalapattar]

Hi! I understand that a 240v AC lamp can be converted to 12v DC by removing..........?

[Alan de Enfield]

4 minutes ago, Kalapattar said:

Hi! I understand that a 240v AC lamp can be converted to 12v DC by removing..........?

The 230v AC plug and the 230v AC bulb fitting and replacing with a 12vDC plug and a 12v DC light fitting

Cable can remain.

[Tony Brooks]

1 minute ago, Kalapattar said:

Hi! I understand that a 240v AC lamp can be converted to 12v DC by removing..........?

 

The bulb?

 

and fitting a 12V one.

 

Only up to a point. The wiring in many lamps may not be thick enough for the higher current that 12V bulbs draw for a similar output. 240V AC LEDs are supplied via "stabiliser/driver" rated for 240V AC. If the driver is in the light fitting then there is the potential for magic smoke to appear.

 

LED "bulbs" for boats and vehicles need their own stabiliser to cope with the sub 12V to 15V voltage variations. 12v ones from domestic suppliers expect to be driven by a driver so do not need a stabiliser. Again, using a 12V DC LED fro a domestic supplier is likely to eventually result filed LEDs or  more magic smoke.

2 minutes ago, Alan de Enfield said:

The 230v AC plug and the 230v AC bulb fitting and replacing with a 12vDC plug and a 12v DC light fitting

Cable can remain.

Not sure the cable bit is correct,  especially if using incandescent bulbs. There are some fittings about with very thin cables. A 21 watt bus bulb will draw close to 2 amps, that's the equivalent to a 500 watt mains bulb.

[Alan de Enfield]

4 minutes ago, Tony Brooks said:

Not sure the cable bit is correct,  especially if using incandescent bulbs. There are some fittings about with very thin cables. A 21 watt bus bulb will draw close to 2 amps, that's the equivalent to a 500 watt mains bulb.

The smallest cable used in lighting was (when I was involved) 0.5mm2 (16/0.20mm) which is rated at 3 amps - 11 amps (depending on test method - 12volt planet suggest 0.5mm2 is OK up to 11 amps)  so would not have any problem with even a 60 watt Incandescent which would probably be unlikely in a NB.

 

 

I guess it may depend on what the OP means by 'lamp'.

The generic term lamp means any 'light' Huge big industrial factory lights are 'lamps' little bed side glow-worms are lamps.

 

I would suggest the man on the Clapham Omnibus woud take a 'lamp' as meaning something like a table lamp, or, a bedside lamp.

 

If it anything 'fixed' then conductor CSA would come into play - possibly more for volt drop than for current rating

 

 

Single core 16/0.2mm cable specification :

 

 

• Manufactured to: ISO 6722:2006 (Class
• Voltage rating: suitable for 12V & 24V systems (60V max.)
• Nominal current rating: 11A
• Maximum loading: 132W@12V,  264W@24V
• No./size of conductors: 16/0.20mm
• Conductor cross section: 0.5mm²
• Maximum overall cable diameter: 1.7mm
• Resistance per m at 20°C: 0.0371 Ω
• Conductor material: Plain copper
• Insulation material: PVC (hard grade) 
• Working temperature range: -40°C to +105°C  (with brief excursions up to +120°C)

[dor]

My wife has a small IKEA ‘anglepoise-like’ light with brick and 230v halogen 20w lamp.

 As suggested I cut off the brick and fitted a 12v led lamp, several years ago now.

Works fine; used when stitching or reading in the evening so not likely to be subject to more than 12.7v.

[Jen-in-Wellies]

2 hours ago, Kalapattar said:

Hi! I understand that a 240v AC lamp can be converted to 12v DC by removing..........?

Depends on the lamp. Have you got any photos, make, model, etc? I've done several on my boat and the method varies depending.

Jen