High resistance

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kennneth1

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Hello everyone,
I'm installing some step lighting in concrete steps to match is already in some existing steps. The total watts for the nine fixtures is 36. The voltage is 120v. The fixtures are warm white LED. I'm coming up with 400 ohms of resistance. This number sounds high to me. What size wire would I use to hook these up? The leads going to the fixture are 22ga.if that helps. Help!
Thanks, everybody.

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Measuring the resistance will tell you nothing, even for an incandescent bulb. You need to look at the labelled current draw on the fixture.
 
kennneth1 said:
Hello everyone,
I'm installing some step lighting in concrete steps to match is already in some existing steps. The total watts for the nine fixtures is 36. The voltage is 120v. The fixtures are warm white LED. I'm coming up with 400 ohms of resistance. This number sounds high to me. What size wire would I use to hook these up? The leads going to the fixture are 22ga.if that helps. Help!
Thanks, everybody.

Sent from my XT1585 using Tapatalk
Click to expand...

P = V x I
36 = 120 x I, so I = 0.3 A total or 33 mA/LED

V = I x R
or R = V/I = 120 VAC / 0.3 A = 400 Ohm

LED drivers generally have a fixed input R, so each LED ~ 3600 Ohm

not sure what code requires, depends on ckt protection (among other things) but I would use #14/15 A CB
 
Ingenieur said:
P = V x I
36 = 120 x I, so I = 0.3 A total or 33 mA/LED

V = I x R
or R = V/I = 120 VAC / 0.3 A = 400 Ohm

LED drivers generally have a fixed input R, so each LED ~ 3600 Ohm

not sure what code requires, depends on ckt protection (among other things) but I would use #14/15 A CB
Click to expand...

Thats assuming unity power factor... Not all LEDs have that, ie capacitive dropper.
 
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