can I use a.c. low voltage bulb on 24v D.C.

[tudorsailor]

Probably a dumb question.

I need to replace a halogen bulb on the yacht. To me it looks identical to a MR16 50mm diameter bulb that I would use in the house.

Would there be any difference between a bulb designed for low voltage a/c and a bulb for 24v d/c?

Thanks for humouring me

TudorSailor

 

[sarabande]

when you say "low-voltage" AC, do you mean a bulb which is used in e.g. a domestic lighting luminaire fed by a 240vAC to 12v or 24v DC track?

You need to match the required input voltage to the bulb; some bulbs have the same physical format but are designed for use with different input voltages.

 

[tudorsailor]

Low voltage A/C. I am referring to a standard low voltage light fed from a 240v-> 12v transformer. In other words the common ceiling downlight that many people have in the home

Thanks

TS

 

[sarabande]

so it looks as if the domestic M16 50mm bulbs will be 12v DC. They will go pop on a 24v circuit after burning brightly for a couple of seconds.


Worth checking with Ultraleds to see if they do 24v LEDS in various warmths ?

http://www.ultraleds.co.uk/mr16-gu53-c-92_94.html

 

[Adrian Jones]

Probably a dumb question.

I need to replace a halogen bulb on the yacht. To me it looks identical to a MR16 50mm diameter bulb that I would use in the house.

Would there be any difference between a bulb designed for low voltage a/c and a bulb for 24v d/c?

Thanks for humouring me

TudorSailor

There are two types of halogen lamps in use in the home MR16 or GU10 the latter designed to be connected to 230V. The former is normally rated at 12V and powered by a local 240/12 Volt electronic transformer. As the halogen lamp is incandescent it will actually function OK on 12v ac or dc. Boat MR11 lamps can either be 12 or 24V and are NOT interchangeable. A 12 volt lamp connected to 24V will fail immediately.

LED, MR16 lamps are readily available for marine use, these can be used with any DC power supply between 10-30V DC. You will soon see more 8-40V versions available on the market. The latter being ideal for a 24V supply. Both versions will typically reduce the load current by 80-90% compared to a halogen lamp with similar effective light output.

Most larger boats were designed with 24V systems as this higher voltage reduces current in the boat wiring and consequently reduces voltage drop at remote parts where winches and the like operate. However with more LED lighting availability many boats are converting their lighting circuits to 12v as LED load current is very much reduced and relatively inexpensive lamps operate more reliably at 12V. Voltage drop on LED lighting circuits is rarely an issue.

Its always worth checking the battery charging voltage on your vessel as sometimes this can exceed 30V. The degree of voltage rise can vary particularly if a modern multi-stage charger is used in equalisation mode. Whilst a 10-30V LED lamp will work effectively, even when voltage rises above 30V for short periods it may reduce the lamp life.

Regards

 

[Norman_E]

On a 24 volt boat, two 12 volt halogen bulbs in series should be quite OK, but a single one will blow.