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-   -   How to know the amount of load a 20amp breaker can take when connecting to 208v? (https://www.askmehelpdesk.com/showthread.php?t=665761)

  • May 31, 2012, 01:11 PM
    dkingsmusic
    How to know the amount of load a 20amp breaker can take when connecting to 208v?
    I in the process of installing lights. These Light uses 208v at 1.35 amps each with a 250w load, how many lights can I install onto a 20amp beakers that is connected to 208v?
  • May 31, 2012, 04:37 PM
    stanfortyman
    Where are you using 208V lights? I assume not in a residence.
    This does make a difference.
  • May 31, 2012, 04:38 PM
    donf
    Quote:

    Originally Posted by dkingsmusic View Post
    I in the process of installing lights. These Light uses 208v at 1.35 amps each with a 250w load, how many lights can I install onto a 20amp beakers that is connected to 208v?

    Since you are using 208V, I am going to guess that you are installing these lights in a commercial environment.

    Given that there is a 10 "Outlet" circuit restriction (NEC imposed) your answer is 10 lights per 20 amp circuit.

    Also, if this is a commercial environment, then only licensed electricians can do the work, also a requirement of the NEC.

    208V is nothing to fool around with. It will literally kill you in a heartbeat if you make the simplest of mistakes. Work on the light circuits must be completed without the circuit being energised.
  • May 31, 2012, 06:04 PM
    stanfortyman
    Quote:

    Originally Posted by donf View Post
    Given that there is a 10 "Outlet" circuit restriction (NEC imposed) your answer is 10 lights per 20 amp circuit.

    Don, can you tell me where you heard of this imaginary code?
  • May 31, 2012, 08:08 PM
    jerro
    You can have up to 3300 watts on 208v, 20 amp breaker. Lighting is usually considered a continuous load ( 3hrs or longer) and can only us 125% of the breaker amperage. 20 amp divided by 125% = 16 amps. 16 x 208v = 3328 watts
  • Jun 1, 2012, 04:03 AM
    stanfortyman
    Quote:

    Originally Posted by jerro View Post
    You can have up to 3300 watts on 208v, 20 amp breaker. Lighting is usually considered a continuous load ....

    ... in a commercial environment...
    Which I would also consider this.

    IMO this should be done by a qualified electrician. Commercial electrical work is not a DIY/handyman kind of thing.
  • Jun 1, 2012, 04:26 AM
    donf
    Quote:

    Originally Posted by stanfortyman View Post
    Don, can you tell me where you heard of this imaginary code?

    Stan,

    You are correct, as usual. I went through the 2008 edition and the 2011 edition of the NEC, no joy.

    I also went through the following books.
  • Jun 4, 2012, 08:56 AM
    dkingsmusic
    Thanks for your help. I got the 10 lights to one 20amp breaker, but just wanted a clarification. Right now we have 30 lights running on 6 20amp breaker. I just needed to add 5 more lights to certain section of the building.

    Thanks everybody.

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