Lights On A Circuit - Role Of Bulb Wattage? - Electrical - DIY Chatroom Home Improvement Forum


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Display Modes
Old 01-24-2012, 10:49 AM   #1
Jack of all - master none
 
hyunelan2's Avatar
 
Join Date: Aug 2007
Location: SW Suburbs of Chicago
Posts: 1,222
Rewards Points: 530
Default

Lights on a circuit - role of bulb wattage?


I have read some conflicting information on the following. Looking for someone to advise.

Facts: Installing 35 recessed fixtures on multiple circuits. The fixtures are made for up to 75w bulbs. I plan on using 15w compact fluorescent bulbs in the fixtures.


When calculating the number of fixtures per circuit, do I need to use the maximum allowable bulb wattage (75), or the intended bulb wattage (15)?

Advertisement

hyunelan2 is offline   Reply With Quote
Old 01-24-2012, 10:51 AM   #2
Just call me Andrew
 
Join Date: Mar 2009
Location: Albany, NY
Posts: 2,258
Rewards Points: 1,012
Default

Lights on a circuit - role of bulb wattage?


The maximum.

At 120v, each lamp could use 75 watts, or 0.625 Amps.

Advertisement

__________________
Andrew

secutanudu is offline   Reply With Quote
Old 01-24-2012, 10:52 AM   #3
Chaos Engineer
 
Big N8's Avatar
 
Join Date: Oct 2009
Location: Coon Rapids MN
Posts: 183
Rewards Points: 150
Default

Lights on a circuit - role of bulb wattage?


+1 to the Maximum.
Big N8 is offline   Reply With Quote
Old 01-24-2012, 10:52 AM   #4
Licensed electrician
 
Join Date: Sep 2007
Location: Maryland
Posts: 8,055
Rewards Points: 2,908
Default

Lights on a circuit - role of bulb wattage?


Even tho you are installing the 15 watt bulbs, someone could later install the 75s.
__________________
Answers based on the National Electrical Code. Local amendments may apply. Check with your local building officials.
Jim Port is online now   Reply With Quote
Old 01-24-2012, 10:56 AM   #5
Jack of all - master none
 
hyunelan2's Avatar
 
Join Date: Aug 2007
Location: SW Suburbs of Chicago
Posts: 1,222
Rewards Points: 530
Default

Lights on a circuit - role of bulb wattage?


Thank you. I agree with all of you, and that is what I thought.

I had someone almost jumping up and down (on the internet) telling me that the circuits only needed to meet the intended use and not the maximum.



One more question. As to the loading of the circuit, is there a recommended cut-off (say 80%) for light fixtures? So, a 15a circuit at 120v would be 1800w, is it advisable to only load it to a maximum of 1440 (80%) or other arbitrary percentage?
hyunelan2 is offline   Reply With Quote
Old 01-24-2012, 11:02 AM   #6
Licensed electrician
 
Join Date: Sep 2007
Location: Maryland
Posts: 8,055
Rewards Points: 2,908
Default

Lights on a circuit - role of bulb wattage?


Residential circuits are not limited to the 80 percent. Rarely, if even would you have all the lighting on for 3 hours or more.
__________________
Answers based on the National Electrical Code. Local amendments may apply. Check with your local building officials.
Jim Port is online now   Reply With Quote
Old 01-24-2012, 11:30 AM   #7
Member
 
Join Date: May 2010
Posts: 78
Rewards Points: 75
Default

Lights on a circuit - role of bulb wattage?


According to cec, you can put a max of 12 devices on each circuit.
fdiddy is offline   Reply With Quote
Old 01-24-2012, 02:07 PM   #8
MarginallyQualified
 
Join Date: Dec 2011
Location: Winston-Salem NC
Posts: 3,820
Rewards Points: 2,314
Default

Lights on a circuit - role of bulb wattage?


Quote:
Originally Posted by hyunelan2 View Post
I had someone almost jumping up and down (on the internet) telling me that the circuits only needed to meet the intended use and not the maximum.
If cord and plug connected and has a UL sticker... Maybe.
Hard wired? Nope.

Quote:
...loading of the circuit, is there a recommended cut-off (say 80%)...
So, a 15a circuit at 120v would be 1800w, is it advisable to only (hard wire connect) load it to a maximum of 1440 (80%)
In short... yes. Not NEC; but "best practices" will limit loads.
Knowing about potential loading is why K&B's require 20A circuits

Advertisement

TarheelTerp is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Light bulb sockets and wattage ratings Richo Electrical 5 12-19-2014 11:42 AM
Voltage drop? Lights dim with load on different circuit. nezwick Electrical 28 08-14-2012 11:18 AM
Wiring in New Addition? sandyman720 Electrical 6 11-27-2011 04:34 PM
Fire Hazard worry on Low wattage recessed lights usng 50w halogen bulbs jomieblumreich Electrical 7 08-15-2009 05:20 PM
Multiple lights and switches on one circuit Straightgrain Electrical 5 03-31-2009 08:34 AM




Top of Page | View New Posts