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-   -   Recessed lights on one circuit (http://www.diychatroom.com/f18/recessed-lights-one-circuit-30973/)

Dean1234 10-31-2008 10:58 AM

Recessed lights on one circuit
 
I am remodeling my basement, however I am stumped on one issue. I plan for 9 Halo 4" recessed lights to run on one 15A circuit. I know the laws of 80% maximum load capacity so that would be 1440. The maximum watts per light in these are 50W, which normally I would think this is no problem (way under). However when looking at the casing of these lights (oh yeah they are IC compatible becasue they will come in contact with the insulation) it says maximum of 6 per 14awg?

Is this something that I should be concerned about? I really don't want to run seperate circuits for the lighting, are they worried the cans get too hot?

any help would be appreciated.

jbfan 10-31-2008 11:33 AM

I think you will find that means a total of 6 14/2 cables max for each light.
Use the max wattage for the fixture you are using to determine how many fixtures to put in.
At 450 watts, you will be fine on a 15 amp breaker.

amakarevic 10-31-2008 12:17 PM

i plan to have an equivalent of about a dozen recessed lights on a single 15A circuit, is that too many ?

i am using HALO H99ICT. i have seen bulbs for that going all the way down to 30W though i am using the 45W or 50W ones.

http://www.cooperlighting.com/specfi..._specsheet.pdf

Bubbagump 10-31-2008 12:18 PM

Yup, I just put in 20 or so of those and it is indeed 6 cables max, not 6 fixtures per circuit. Note there are 6 punch outs on the junction box. ;)

amakarevic,
12 lights at what wattage each? 4 watts? 1000 watts?

P=VI so

In your case assuming 60 watt lamps

P= 12 * 60 = 720 total watts

720 = 110 * x
x= 6.5 amps

6.5 amps nominal use is fine for a 15 amp circuit.

For 100 watt lamps

P = 100 * 12 = 1200 total watts

1200 = 110 * x
x = 10.9 amps

10.9 amps might be pushing it as I personally like to put things at about 50% of circuit capacity.

amakarevic 10-31-2008 12:26 PM

Quote:

Originally Posted by Bubbagump (Post 179151)
Yup, I just put in 20 or so of those and it is indeed 6 cables max, not 6 fixtures per circuit. Note there are 6 punch outs on the junction box. ;)

bubba, did you put the 20 lights all on the same circuit ?

Bubbagump 10-31-2008 12:36 PM

Quote:

Originally Posted by amakarevic (Post 179153)
bubba, did you put the 20 lights all on the same circuit ?

NO! There were 4 separate circuits, each with 6-8 recessed lights on each and maybe a closet light or two. On a side note, I love how the housing is like $6 and the trim is like $20. Bastages.

amakarevic 10-31-2008 12:40 PM

i think i will go with 45 or 50W bulbs on each light. thanks for laying out the formula for wattage vs. voltage vs. amperage, i was gonna start a separate thread to ask how it is done. but it looks simple enough.

W = A * V, correct ?

Bubbagump 10-31-2008 12:45 PM

Quote:

Originally Posted by amakarevic (Post 179162)
W = A * V, correct ?

Yup. As a rule of thumb, on 110/120 AC circuits you can estimate 100 watts per amp. This gives a little padding and is easy to do in your head. So 10 100watt lamps estimates out to 10amps.... the real math puts it at 9.09 amps, but with my estimation you have a built in bit of wiggle room slightly under the actual usage. What will be interesting is if incandescents go the way of the dodo with CFLs coming in, in another 10 years we may be putting all sort of lights on a single circuit.


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