# Stupid Question-Is Low Voltage AC or DC?



## Tscarborough

Lighting, that is. I dunno, I thought it was all DC at least on the low end.


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## Hmrepairs

DC, I believe.


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## avguy

I've seen the odd 24V AC unit, but most are 12V DC.


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## thom

There are a lot of low voltage AC applications. Take your doorbell for example................................


Of course there are a lot of low voltage DC applications also.

Since you asked in the landscape section, maybe you are considering landscape lighting. Regular incandescent bulbs work just fine on either AC or DC, LED's will work on AC if you don't overpower them but they will be off 1/2 the power cycle since diodes only allow power to pass one way, though generally they are DC. You will have more voltage loss on long runs with DC. Landscape lighting systems are made both ways.


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## GettingBy

thom said:


> Regular incandescent bulbs work just fine on either AC or DC, LED's will work on AC if you don't overpower them but they will be off 1/2 the power cycle since diodes only allow power to pass one way, though generally they are DC. You will have more voltage loss on long runs with DC. Landscape lighting systems are made both ways.


Supplying DC should cost more because of the diodes.

Incand. life is different for AC than for [filtered?] DC; one of them causes filament notching.

LEDs, like fluorescent tubes, should be driven from a current source and not a voltage source so there might be some electronics involved in the LED driver circuit which may compromise the overall reliability of the LED lighting system.

The AC skin effect is almost negligible at 60 Hz so voltage drop along small conductors should be the same for AC or DC and depends on current and the conductor loop resistance. 100' of #14 AWG copper @ 20 C gives you 260 milliohms of resistance and at 1 A would drop about 1/4th volt.

The perceived shock intensity is different for 60 Hz AC, 10 kHz AC and DC.

To be certain, check with your multimeter.


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