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In DC systems, what could be an advantage of lower-voltage (higher-current) light bulb over a higher-voltage one, assuming the input power is the same? What could be a higher-voltage (lower-current) light bulb's disadvantage? Would the low volt high current lamp have a longer life because its filament has thicker wire that would take longer to evaporate ? Would the low volt bulb be less likely to fail when vibration is an issue ? Would the low volt lamp be able to run a higher filament temp leading to more lumens per watt?

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  • \$\begingroup\$ Can you link to a particular product you're looking at? If they run on less than 50 V, that's a voltage that isn't likely to electrocute anybody. \$\endgroup\$
    – The Photon
    Oct 25, 2016 at 4:11
  • \$\begingroup\$ I'm looking at a difference between a 70 and 80 V light bulb \$\endgroup\$
    – rocketeer
    Oct 25, 2016 at 4:32
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    \$\begingroup\$ There is no difference between 70 and 80, practically speaking. Whatsoever. \$\endgroup\$ Oct 25, 2016 at 5:47
  • \$\begingroup\$ Datasheets, or make and model number, please. \$\endgroup\$
    – user57037
    Oct 25, 2016 at 5:52
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    \$\begingroup\$ The difference between 70V and 80V is essentially zero. Since you have not revealed other critical factors in your decision, we can offer only generic suggestions like avoiding adding additional power voltage sources for economic reasons. Neither 70V or 80V can be considered "low voltage" by most standards. Likely many bulbs can operate effectively over that range of voltages without having to select one or the other. \$\endgroup\$ Oct 25, 2016 at 6:23

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Low-Voltage incandescent lamps can withstand significantly-more vibration than high-voltage lamps. This is because the filament is thicker, which makes it more sturdy.

This property of low-voltage incandescent lamps is one of the many reasons that 42 Vdc vehicle electrical systems never became popular. There are other reasons - this was just one.

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  • \$\begingroup\$ If the automotive industry moves to all LED lighting, this advantage may be less important in the future. \$\endgroup\$
    – user57037
    Oct 25, 2016 at 5:53
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I'm looking at a difference between a 70 and 80 V light bulb

There's likely no particular advantage to one or the other. If you are using 70 V elsewhere in your system, choose the 70 V one. If you are using 80 V elsewhere in your system, choose the 80 V one.

If you aren't using these voltages except to power the light bulb, use whichever one makes your system cheaper.

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  • \$\begingroup\$ Why would you advise being consistent with the voltages? \$\endgroup\$
    – rocketeer
    Oct 25, 2016 at 4:43
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    \$\begingroup\$ Because it's cheaper to use a voltage you already have in your system than to add a transformer or converter to produce some other voltage. \$\endgroup\$
    – The Photon
    Oct 25, 2016 at 4:43
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Low voltage lighting is often used for safety reasons. For example, in outdoor lighting for homes.

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Some low voltage light producing devices use less energy per lumen. In those cases, your energy bill would be less.

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