Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 21

Thread: Fixtures Per Circuit

  1. #11
    Join Date
    Sep 2012
    Location
    NJ
    Posts
    1,593
    Quote Originally Posted by gar View Post
    171011-1256 EDT

    You really need to know more about the driver to determine if it is advisable to put that many on the circuit.

    .
    Like??

  2. #12
    Join Date
    Apr 2008
    Location
    Ann Arbor, Michigan
    Posts
    6,255
    171011-1622 EDT

    A 9,5 W Phillips LED bulb may have a peak inrush current of 6 A measured with a 2 ohm resistor. This inrush is very short. Damped oscillation lasts about 1.5 milliseconds.

    What you switch or control this circuit with may be the limiting factor rather than the wire or breaker.

    What kind of inrush current your drivers have needs to be known. Knowledge of just a steady state load current is possibly insufficient. Note, 30*6 = 180 A. A single 100 W incandescent can have a peak inrush of 16 A. Would you put 16 or more of these bulbs on one circuit, and switch them simultaneously?


    .

  3. #13
    Join Date
    Sep 2012
    Location
    NJ
    Posts
    1,593
    Quote Originally Posted by gar View Post
    171011-1622 EDT

    A 9,5 W Phillips LED bulb may have a peak inrush current of 6 A measured with a 2 ohm resistor. This inrush is very short. Damped oscillation lasts about 1.5 milliseconds.

    What you switch or control this circuit with may be the limiting factor rather than the wire or breaker.

    What kind of inrush current your drivers have needs to be known. Knowledge of just a steady state load current is possibly insufficient. Note, 30*6 = 180 A. A single 100 W incandescent can have a peak inrush of 16 A. Would you put 16 or more of these bulbs on one circuit, and switch them simultaneously?


    .
    Says in rush current is less than 2 amps

  4. #14
    Join Date
    Apr 2008
    Location
    Ann Arbor, Michigan
    Posts
    6,255
    171011-2448 EDT

    With a Costco 4 foot two tube 36 W shop light I recorded one inrush pulse at about 10 A for about 2 milliseconds. This is closer to the power of one of your drivers. Still using 2 ohms to measure current.

    You really need to make actual measurements on your driver.

    With such data, then it becomes necessary to figure out how that may affect your application. This is the hardest part. Note that peak pulse input current is a function of how fully discharged is the driver input capacitor and where in the AC cycle power is applied.

    .

  5. #15
    Join Date
    Feb 2016
    Location
    Illinois
    Posts
    407
    Is inrush with a duration of a fraction of a 60 HZ cycle relevant when determining how many fixtures per circuit?

  6. #16
    Join Date
    Apr 2008
    Location
    Ann Arbor, Michigan
    Posts
    6,255
    171012-0918 EDT

    Possibly.

    .

  7. #17
    Join Date
    Jan 2016
    Location
    PA
    Posts
    3,764
    Quote Originally Posted by gar View Post
    171012-0918 EDT

    Possibly.

    .
    assume 1.5 ms = 3 time constants, impulse reduced by 95%
    so peak ~ 0.5 ms
    0.03 cycle
    can a molded case cb react to that?
    or a switch issue?



  8. #18
    Join Date
    Apr 2008
    Location
    Ann Arbor, Michigan
    Posts
    6,255
    171012-1037 EDT

    Ingenieur:

    The Costco pulse I measured was fairly close to a rectangular pulse of about 10 A and duration of 2 milliseconds. I did not run a controlled experiment where I could define the turn on point. I simply used a plug as the switch, and tried enough times with random turn on to get a reasonably large pulse.

    If I had a 300 A pulse like this I think it would trip a QO20. The energy imparted to the breaker will determine if it trips or not. If not on the first pulse, then quite likely on a second or third pulse. Note a QO is thermal-magnetic in its trip mechanism.

    If you do not actually trip a breaker the latch mechanism may move some, stay put because of friction, and trip easier on a subsequent pulse.

    .

  9. #19
    Join Date
    Jul 2003
    Location
    New Jersey
    Posts
    23,556
    Quote Originally Posted by retirede View Post
    Is inrush with a duration of a fraction of a 60 HZ cycle relevant when determining how many fixtures per circuit?
    Rob

    Moderator

    All responses based on the 2014 NEC unless otherwise noted

  10. #20
    Join Date
    Apr 2007
    Location
    Huntington Beach, CA (19 Hrs. 22 Min. from Winged Horses)
    Posts
    6,081
    Quote Originally Posted by gar View Post
    171011-2448 EDT
    You really need to make actual measurements on your driver.
    .
    +11eventeen on that.

    to the OP:

    this is an eco driver. digital, addressable, runs on a lutron
    eco system. grafik eye, quantum, etc. requires an interface,
    supporting 64 devices. can NOT be commingled with 0-10 v.
    controls on the same bus. a common error. lutron's 0-10
    driver looks almost the same to a lot of electricians. trust me.

    how much it draws depends on what it's hooked to. i've seen
    this driver on fixtures drawing anywhere from 3 watts to 40 watts
    per fixture.

    so your question is not able to be resolved with your information.
    what fixture is it on? case in point. observe this fixture below:

    Name:  lights.jpg
Views: 80
Size:  95.2 KB

    these are independent fixture heads. each one draws about 4 watts
    each, measured with a wattmeter. PER HEAD. here is the fun part.
    each fixture has TWO of those eco drivers, so each light can be controlled
    independently.

    so, as the EE didn't pay attention to this fact, his design allowed
    for one eco single loop control panel, controlling 64 devices.
    he ended up needing four single loop controllers, or two double loop
    controllers.

    but it gets better. the fixtures were tied together using MC cable with
    control wires in them, as is common practice. you can put far more
    devices on that 20 amp circuit than you can logically address with one
    controller. you can put them in an inaccessible hardwood ceiling, stained.
    you can cry sad tears when you have to fix it.

    you can put 240 of those luminaries on a single 20 amp circuit. then, you
    can split it eight times to get it to work. you will have 480 addressable
    drivers. let's hope the ceiling is accessible.

    you really need to understand the systems you are working with before
    designing for them....
    ~New signature under construction.~
    ~~~~Please excuse the mess.~~~~

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •