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I acquired a fixer upper house built in the early 1950s. I looked into the electrical box and all the breakers there. It looks like some random assignment of breakers to the points of use throughout the house. For instance there is a sole receptacle (right under the electrical box) that has its own breaker rated 20amp. But the whole second floor (with all its receptacles and switches) is under one breaker rated 15AMP. Same thing with the whole kitchen. So I am puzzled or confused as to the power I can run simultaneously, say in the kitchen. Say on one receptacle I may have a small fridge (200W), a coil water boiler (1000W) and a toaster (700W). I am thinking that my circuit breaker (15A) will turn itself off if I run those three at the same time? What about if I run three appliances simultaneously, totaling 2000W, but plugged into different receptacles in the same kitchen? Will the sole 15A breaker switch off, or am I OK to run the appliances at the same time? P.s. I am talking in 120V environment.

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  • I wonder why this was migrated? The question is about operating characteristic of a circuit breaker. Isn't that engineering, not home improvement? Mar 19, 2021 at 1:19
  • @NoSparksPlease At one level it is about the electrical engineering. But in a broader sense it is about "how does house wiring work and why is mine so strange". Mar 19, 2021 at 4:03
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    You should probably check the way things are actually wired, like whether the outbound wire to the kitchen is actually a 3 wire cable which would indicate there should be 2 15 amp circuits on a double breaker with a shared neutral. Are you sure that's not what you have? As for the rest of the house you can check for any other outgoing 3 wires on receptacle circuits for the same reason and also check if any breakers have wires doubled up on them, which is forbidden but not uncommon where breakers have been moved around or not enough slots were available.
    – K H
    Mar 19, 2021 at 5:41
  • Incidentally if there is a 20A breaker for the plug by your panel, you can check if they used 20A(12 AWG) wire and a 20A plug (similar to 15A but with a T slot on the neutral so 15A devices can plug into 20A receptacles and not vice versa).
    – K H
    Mar 19, 2021 at 5:44
  • K H OK, I will check that
    – Rado
    Mar 21, 2021 at 23:30

3 Answers 3

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Sounds a lot like my house before I redid my kitchen. Current code requires at least two 20A circuits in the kitchen, for exactly the reasons you stated. My kitchen used to be almost all on one circuit (except the oven & cooktop). I also have one 15A circuit that powers: kitchen lights, cooktop hood fan/light, 1/2 the bedroom lights & receptacles and 1/2 the main basement room lights & receptacles. Not unusual at all for the 1950s.

But why, you ask, if so much is crammed on each 15A circuit, is there a 20A circuit with just the one receptacle at the panel? Very simple: Your house, like mine, originally had a fuse box rather than breakers. Or even multiple boxes, using the Rule of Six. I still have mostly fuses, except for a small breaker panel added when I redid my kitchen.

In your case, my hunch is that a previous owner decided to replace the fuse box(es) with a nice big panel. When they did that, the electrician added, at very low cost, a convenience receptacle next to the panel. It is quite likely the electrician added some new circuits somewhere, but didn't bother (because it wasn't a problem at the time) to replace the existing circuits. Any of those old 15A circuits that included 14 AWG wire couldn't be changed to 20A, so even though that would be useful, especially in the kitchen, the existing circuits had to get 15A breakers.

If you have room in the panel, you can wire up new circuits to the kitchen. If you do that, they should be 20A and they must have GFCI, either in the breaker or at the first receptacle in each series.

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  • manassehkatz-Moving 2 Thee panel has perhaps 6 (or more spare slots). Curiously, there is a fuse box, going from that panel, about 7 feet away with two fuses one fast one slow acting. I found one line going up to the kitchen -- it was running a dishwasher that I disposed of. All tubing is metal, except that line that is not. I did put one GFCI in the kitchen -- it was a heroic feat since I had to physically enlarge space to put in the GFCI. Things work, but thee wiring is old (70 years); on the other hand, it is too late for me to rewire thee whole hose.
    – Rado
    Mar 21, 2021 at 23:23
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If what you say is true, that the entire kitchen runs off of only one 15 amp circuit breaker, then you are limited to 15 amp no matter how many different outlets you use in the kitchen. However, you probably should try to confirm that. Turn the breaker off and check that every outlet in the kitchen is off.

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  • Barry, the first thing I did when I got juice was to check the correspondence of breakers to switches and receptacles. Made detailed list placed in a couple of places and also put tiny stickers on ever receptacle/switch with number of breaker controlling it. Yes, I will test by overloading and see what happeens.
    – Rado
    Mar 21, 2021 at 23:27
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When functioning properly breakers trip on an inverse time curve. 2000w (16.6A) is even within the range of never tripping and still within tolerance of many brands.

You may also have some added resistance from bad connections, which reduces current and amps. But you ask if OK? Do you mean safe? My inclination is to say no. Everything wears out, it's a function of the second law of thermal dynamics. Running something at full capacity near end of life isn't advised. Failure is definite, hopefully you update before the impending failure is catastrophic.

Here is a typical time curve, your brand will likely vary some. Notice at least one current line: 125% should hold for about 300 seconds (5 minutes), and then just enter the possible trip band, then following the timeline upward you can see it never leaves the undetermined zone.

breaker inverse time curve

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  • NoSparksPlease thanks for the chart, which looks interesting. I will see how much gold it contains...
    – Rado
    Mar 21, 2021 at 23:28

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