Calculating load for LED strip lighting

[olly]

If the strip light is 1.46 watts per foot at 12v. Is it as simple as:

1.46 / 12 = . 121A per foot.

So if I were to have 15' it would be

15 x 1.46 = 21.9 watt

21.9 w / 12v = 1.8 A is what this LED strip will draw?

 

[James L]

Yep. It's straightforward like that

 

[James L]

An extra bit of info.
I've looked at the voltage drop on a 2 amp load at 12 volts

Basically, you can go a maximum of 27 feet including the length of the strip if you use 18 gauge wire

 

[petersonra]

An extra bit of info.
I've looked at the voltage drop on a 2 amp load at 12 volts

Basically, you can go a maximum of 27 feet including the length of the strip if you use 18 gauge wire

are you basing this maximum length on some arbitrary voltage drop?

 

[olly]

Yep. It's straightforward like that

Thanks James. One more follow up. Can I tap off of the microwave circuit? I haven't been able to find in code if the microwave cannot have anything else on it. I would think 1.8A isn't going to cause problems?

 

[James L]

are you basing this maximum length on some arbitrary voltage drop?

Not arbitrary, just what I've observed as minimum voltage required so as not to affect brightness from one strip to another, which is about 11.5v

That amounts to right at 4% vd

 

[James L]

Thanks James. One more follow up. Can I tap off of the microwave circuit? I haven't been able to find in code if the microwave cannot have anything else on it. I would think 1.8A isn't going to cause problems?

Functionally there wouldn't be a problem.
But microwave probably calls for dedicated circuit

 

[LarryFine]

21.9 w / 12v = 1.8 A is what this LED strip will draw?

Yes, but the power supply's draw from the source will be a bit higher.