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  • 15 vs 20 amp breakers

    A recent home inspection requested I change a 20 amp breaker to a 15 amp breaker. It's one that's been there since I bought the home. I have both in the box, how can I tell which to use for each line?

    Also, I'm changing regular outlets to be GFCI, how do I know if they should be 15 or 20? Match the breaker amp?

    Thanks, Karen

  • #2
    Re: 15 vs 20 amp breakers

    Look at the size of the wires, a 14ga wire is a 15 amp circuit. A 12 gauge wire is a 20 amp circuit. For GFI's, match the size of the breaker (or go with a 15 to be safe) Sometimes people run 12 ga wire and put on a 15a breaker.

    Gauge (ga.) stands for the size, or thickness of the wire.
    We don't have preventative maintenance around here, we have CRISIS MANAGEMENT!

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    • #3
      Re: 15 vs 20 amp breakers

      The smallest gauge wire in the circuit determines the maximum size of the breaker.
      Did someonextend a 12-gauge wire (20 amp) circuit with 14-gauge wire?
      Last edited by Robert Gift; 10-22-2011, 06:39 AM.
      I'd take an educated guess - but I'm unqualified.
      It ain't just soot, it's paydirt.
      "I swear, wherever Gift goes, argument follows." -Youtube comment

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      • #4
        Re: 15 vs 20 amp breakers

        I don't know what was run. Actually, it turns out the breaker is one that was used when an HVAC guy installed a ductless AC for me a couple months ago. So I'm surprised that's not correct. I'll give them a call to come take a look.

        But for my own education. When you talk about circuit, is that the one line from the box out to the outlets? Or is that the full system. As I said, I have 20s and 15s in the box, should I find 12 gauge hooked up to the 20 amp and 14 gauge with the 15 amp?
        Last edited by KarenLeePA; 10-21-2011, 04:52 PM.

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        • #5
          Re: 15 vs 20 amp breakers

          Originally posted by KarenLeePA View Post
          I don't know what was run. Actually, it turns out the breaker is one that was used when an HVAC guy installed a ductless AC for me a couple months ago. So I'm surprised that's not correct. I'll give them a call to come take a look.

          But for my own education. When you talk about circuit, is that the one line from the box out to the outlets? Or is that the full system. As I said, I have 20s and 15s in the box, should I find 12 gauge hooked up to the 20 amp and 12 gauge with the 15 amp?
          If you aren't sure what a circuit is and not sure of wire gauges, are you sure? These are things you should know when playing in a panel. One mistake in there can get real expensive! A pro cost less than a hospital bill or a fire. Just a thought.

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          • #6
            Re: 15 vs 20 amp breakers

            Understood. I've changed the breakers before. I just replace it with whatever amp the one that blew was. Not playing around, just curious about the fact that there are different amp breakers. I can certainly replace a 20amp breaker with a 15amp one if needed. I wanted to understand why he required the change. In looking at it further, it does look like someone ran a 12 gauge wire off a 14 gauge. I'm following up with the company that installed it.

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            • #7
              Re: 15 vs 20 amp breakers

              Originally posted by KarenLeePA View Post
              As I said, I have 20s and 15s in the box, should I find 12 gauge hooked up to the 20 amp and 14 gauge with the 15 amp?
              Yes, but sometimes people run 12ga and put a 15 amp breaker on it.
              We don't have preventative maintenance around here, we have CRISIS MANAGEMENT!

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              • #8
                Re: 15 vs 20 amp breakers

                Originally posted by KarenLeePA View Post
                I don't know what was run. Actually, it turns out the breaker is one that was used when an HVAC guy installed a ductless AC for me a couple months ago.
                Well wire sizes for A/C systems follow different codes than other circuits, so there is a good chance the HI didn't have a clue about this.

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                • #9
                  Re: 15 vs 20 amp breakers

                  Originally posted by Speedy Petey View Post
                  Well wire sizes for A/C systems follow different codes than other circuits, so there is a good chance the HI didn't have a clue about this.

                  Really? I was always under the assumption that 14ga=15, 12ga=20a, 10ga=30a unless there was a reallllly long run, in which case a smaller breaker was used... I am not an electrician, but I did sleep at a Holiday Inn Express a couple of times!
                  We don't have preventative maintenance around here, we have CRISIS MANAGEMENT!

                  Comment


                  • #10
                    Re: 15 vs 20 amp breakers

                    Sorry , but from what You've posted You're over Your head. Call an electrician before someone finds You dead in front of Your main panel! Breaker choice is not like vanilla vs chocolate ice cream.
                    Last edited by toolaholic; 10-22-2011, 04:53 AM.
                    I can build anything You want , if you draw a picture of it , on the back of a big enough check .

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                    • #11
                      Re: 15 vs 20 amp breakers

                      Originally posted by masterbeavis View Post
                      Really? I was always under the assumption that 14ga=15, 12ga=20a, 10ga=30a unless there was a reallllly long run, in which case a smaller breaker was used... I am not an electrician, but I did sleep at a Holiday Inn Express a couple of times!
                      Motors and A/C units have their own rules. Without getting too technical it is perfectly normal to see a 50A breaker with #10 wire, or maybe a 40A with #12, and this is safe and legal. It has to do with minimum circuit ampacity and maximum breaker ratings.
                      Show that to the typical HI and he'll sound every alarm he has.

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                      • #12
                        Re: 15 vs 20 amp breakers

                        End result. AC wire was 12 gauge with a 14 gauge extension wire. There was a double breaker at the top that had nothing hooked up to it. Moved that down to the bottom, moved the bottom two to the top, removed the extension wire. Problem solved.

                        Thank-you all for explaining the wire gauge/amp relationship. As I said, I simply replace what's already there without question. Your information helped fix it when it was wrong.

                        I'm very careful when in the main panel to change a breaker. I turn off the main and use a head lamp even when I'm just changing a breaker (maybe overkill). I touch nothing other than the breaker and reattach wires before I connect the breaker.

                        All good. Thanks!

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                        • #13
                          Re: 15 vs 20 amp breakers

                          Like they say "The best Man for a job, is often a Woman!" You rock Karen !
                          I can build anything You want , if you draw a picture of it , on the back of a big enough check .

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