Quick electrical question

Collapse
This topic is closed.
X
X
 
  • Time
  • Show
Clear All
new posts
  • wwday3
    Forum Newbie
    • Jan 2004
    • 71
    • Eagle, ID, USA.

    Quick electrical question

    This may seem like a stupid question, but here goes....

    When a 220V appliance calls for a 50A breaker, does that mean "per leg" or in total? Should it be a double breaker with '50' on each side, or a double breaker with '25' (in there such an animal?) on each side?

    Like I say, it may seem like a stupid question to you old pros out there, but I was looking in my breaker box and got to wondering...
    Two wrongs do not make a right, but three rights do make a left.
  • Nick Keenan
    Established Member
    • Apr 2004
    • 441
    • washington, dc, USA.

    #2
    It means 50A at 220V, which is a way of saying 50A per leg. This is two breakers tied together so that if one trips it takes the other with it. It usually takes up two slots in the box.

    Comment

    • HomerJ
      Established Member
      • Oct 2004
      • 157
      • Canada.

      #3
      quote:Originally posted by Nick Keenan

      It means 50A at 220V, which is a way of saying 50A per leg. This is two breakers tied together so that if one trips it takes the other with it. It usually takes up two slots in the box.
      Nick is right. But if you're running out of space in your box, you can get "slim" breakers, wich take up only 1 slot for the 220V, and give you 2 lower amp (say 15 or 20A) circuits in another slot. You end up taking 2 slots for 2 110V and 1 220V circuits. With some imagination you can rewire the box to get some breathing space. My main panel is a mix of full size and 1/2 size breakers. (And double size for the darn 60A GFCI wife's spa circuit) Grrrr...

      Comment

      • don_hart
        Veteran Member
        • May 2003
        • 1005
        • Ledayrd, CT, USA.

        #4
        Actaully the slim breaker will not give you 220v If you installed a slim line breaker that takes on slot and wired the two wires from it to your appliance there would be zero volts at the appliance. With a single slot dual slimline breaker both sides of the dual breaker are atached to the same phase.

        Don Hart

        You live and learn. At any rate you live.

        www.hartwoodcrafts.com



        Comment

        • tfischer
          Veteran Member
          • Jul 2003
          • 2343
          • Plymouth (Minneapolis), MN, USA.
          • BT3100

          #5
          quote:Originally posted by don_hart

          Actaully the slim breaker will not give you 220v If you installed a slim line breaker that takes on slot and wired the two wires from it to your appliance there would be zero volts at the appliance. With a single slot dual slimline breaker both sides of the dual breaker are atached to the same phase.
          Sounds like HomerJ is talking about something that fits 3 breakers in the space of two (actually saving you 4 slots, since the double-pole breaker would normally take 2 slots).

          I've never seen such a beast, but I'd be interested in seeing one, if anyone has a link.

          I've pretty much maxed out our panel, so this might come in handy someday...

          -Tim

          Comment

          • DaveS
            • May 2003
            • 596
            • Minneapolis,MN

            #6

            (well, now that we have drifted off topic a bit)

            hmm.... I wonder if there is such a thing as a "double gang" 220v breaker - which still occupies two slots, but contains two 220v breakers. Anyone?

            While I am no electrician - but I've seen a lot of panels, and I've never seen a 220v breaker that did not occupy 2 slots. There are plenty of "double gang" 110 breakers, but that's different. 220v needs one hot connection from each leg of the incoming power (assuming a normal household). The way the panels are wired is that every other slot is on the same leg. So - when a 220v breaker is inserted, it contacts two sequential slots - thus one hot from each leg. When you put in a "double gang" 110 breaker, it puts both those circuits on the same leg (which is allowed).

            When replacing a single breaker with a double gang breaker, I wonder if it would be wise to keep the circuits on the original legs.

            For example: in the panel

            Ckt 1
            Ckt 2
            Ckt 3
            Ckt 4

            Circuits 1 and 3 are on the same power leg. Circuits 2 and 4 are on the same power leg. When an electrician plans a house, they are supposed to balance the circuits across the two legs (for example, putting the microwave circuit on a different leg than the dishwasher). I'm not sure how much that happens, or even it is important.

            Any way, back to my example: when replacing 2 breakers with a double gang - use ckt 1 and 3, then the panel now looks like this:

            Ckt1,Ckt3 (double gang)
            Ckt2
            OPEN
            Ckt4

            When you wire your shop, you might want to be concious of these things as well. For example, put the air compressor circuit on a different leg than the dust collector.

            I don't think it matters as far as your electric bill goes (I think you are always billed for the power you use, in spite of any imbalance there may be).

            Any electricians in the house that can confirm if this is important, or even true?

            Comment

            • LarryG
              The Full Monte
              • May 2004
              • 6693
              • Off The Back
              • Powermatic PM2000, BT3100-1

              #7
              quote:Originally posted by DaveS

              When you wire your shop, you might want to be concious of these things as well. For example, put the air compressor circuit on a different leg than the dust collector.
              Or a different leg from the shop lights. When I put the new 60A subpanel in my shop, I found with my initial configuration that turning on the DC would cause the fluorescent lights to dim. Unplugging the breakers and rearranging them so they were on different legs completely eliminated this problem.
              Larry

              Comment

              • HomerJ
                Established Member
                • Oct 2004
                • 157
                • Canada.

                #8
                quote:Originally posted by don_hart

                Actaully the slim breaker will not give you 220v If you installed a slim line breaker that takes on slot and wired the two wires from it to your appliance there would be zero volts at the appliance. With a single slot dual slimline breaker both sides of the dual breaker are atached to the same phase.

                What I'm talking about is a breaker that takes 2 slots, and give you 110 (1/2 slot) 220 (1 slot) 110 (1/2) slot. Each side of the 220 is connected to a different leg. It has to work else someone has changed everything I have at home to battery power without telling me

                I guess my description is not too good. I can take pictures if anyone is interested.

                Comment

                Working...