Breakers: criteria for selection?

Discussion in 'Electrical Forum discussion & Blog' started by Fistor, Jun 27, 2008.

  1. Fistor

    Fistor Geotechnical Engineer

    Messages:
    48
    Location:
    Vancouver, BC
    Hi all -

    Just wondering if someone could give me a quick review rundown on the criteria for selecting breakers for the panel.

    As I understand it, you need to consider:
    - make (e.g. Siemens)
    - amperage (e.g. 15-A)
    - single/double pole

    Anything else?

    Also, what physically is the difference between single- and double-pole breakers?

    Thanks!
  2. Bill Arden

    Bill Arden Computer Programmer

    Messages:
    584
    Location:
    MN, USA
    A double-pole breaker is twice as wide and has two power wires.

    They also make triple pole breakers for 3-phase panels.

    the brand/make/type is the most important as you can't put a homeline breaker into a QO panel even though they are both from Square D
  3. Fistor

    Fistor Geotechnical Engineer

    Messages:
    48
    Location:
    Vancouver, BC
    What is "QO" - is that a make, or a type?

    I ask, since I tried looking at the small print on all the breakers already installed, and noted that they are marked with "Q-" designations.

    So, I am right to assume that not all Siemens, 15A, single-pole breakers are equal? (ignoring GFCI and AF types)

    If so, what additional criteria are there, and what do they mean?
  4. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    A panel will be labeled to say what TYPE number of breaker may be used. Q0 is a certain Square D type. There are other Square D breakers which are different types, and not interchangeable with Q0. So that TYPE number is a key spec.
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,892
    Location:
    New England
    There are also special CB, such as GFCI and AFCI which may be required for certain applications. When you get into special equipment, there are all sorts of special CB with various tripping profiles. Some are designed for big surges, such as things that control a compressor or big motor.
  6. Fistor

    Fistor Geotechnical Engineer

    Messages:
    48
    Location:
    Vancouver, BC
    Awesome, thnx for the info. My panel is a Siemens, with no special indicators (e.g. Q0). I will just make sure to match the new breaker type to the existing.

    Besides, after having first asked this question, I did a lot of checking around, and note that Siemens (whom I thought were among the largest) seem to have less variety and variations on their breakers (at least judging by available selection at hardware stores - Square D seems to dominate).Thnx again for all the answers! :)
  7. mattbee24

    mattbee24 In the Trades

    Messages:
    100
    Location:
    Fremont, OH
    For residential panels, Siemens only has 2 styles of breakers. And only 1 is currently being used on any new panels. There is the pushmatic style which Siemens recently stopped making, and the QP series breakers. If you have to "push" the breaker to turn it on/off, it is a pushmatic. Otherwise you have the QP series. The QP series will interchange with a number of other brands.
  8. mattbee24

    mattbee24 In the Trades

    Messages:
    100
    Location:
    Fremont, OH
    Yep Andy. Still live on Morrison.
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