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I've been trying to find more information on how cheaters work but could never come to a definite decision on how many total amps they might pull.

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Basically my question comes down to this:

  1. In the image above, the sub unit is supplied with a max of 125 Amps. Does the two pole 20 Amp "cheater" supply a maximum of 20 Amps or 40 Amps?
  • a) If it supplies a maximum of 40 amps, then wouldn't that mean the total possible Amperage that it could try to pull would be 130 Amps, and thus could try to overdraw power, and would pop the main breaker?
  • b) If it supplies a maximum of 20 amps, could I safely swap out one of the 15 amp breakers for a 20 amp breaker, provided the cables used are 12 Gauge?
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Ok first we don’t add values up like that but a cheater, tandem or double stuff is rated for the amperage on the handle so yes that cheater can draw up to 40 amps without tripping on that one leg 20 at each breaker. What if you put a 60 amp breaker in that panel that and a 40 and 4 20’s , it is possible it would be just fine we add up the loads on the circuits and in some cases may not count one, for example the 60 for an electric heater and a 40 for a AC unit you would only count the 60 the 40 not running the same time as the 60, this is all part of load calculations your 15 amp breaker will rarely have 12 amps on them when they do have that or 15 it is usually for short periods of time. These are additional safety’s built into code and the diversity of the loads makes a difference SO is your box overloaded? Not even close you really could have much larger breakers as my examples tried to show you are probably drawing just about 1/2 the rated current of this sub and your limiting factor is the breaker feeding it if you have a 125 amp breaker feeding this sub it will protect the panel.

You have a circuit that is all 12 gauge wiring and would like to bump the breaker from a 15 to a 20 go ahead , at some point if you start tripping your main you have gone two far but I rarely see that with all small breakers and a few tandems . As long as your panel is rated for tandems it is fine the buss can handle the load. If they are true cheaters (non current limiting) devices you may overload that buss location but I doubt it with a 15 full size on the other side.

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  • Thanks, I meant to mention in the question, that the main thing I wanted to solve is if it would generally be safe to upgrade the 15 amp to a 20 amp circuit, but incorrectly assumed it wouldn't be smart to potentially overdraw the circuit with the amperage in the first place.
    – Max
    Commented Jul 8, 2020 at 20:14
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    You will be fine I would do it on this panel with out measuring as long as the circuit wire is 12 awg.
    – Ed Beal
    Commented Jul 8, 2020 at 20:19
  • What do you mean by overload that buss location? If the cheater breakers do not limit current - that seems crazy - then you could draw more current then the wire connecting to those breakers is able to handle with out tripping the breakers and the wire could start to melt and start a fire? I am assuming cheaters can't be code approved.
    – Fresh Codemonger
    Commented Jul 8, 2020 at 21:10
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    @fresh codemonger , a non CTL breaker is for replacement only these were popular in the early days of circuit breakers back when we had the crazy 20 or 24 limit prior to the CTL rejection feature that’s why they were called cheaters . I mis spoke or typed the name is non circuit limiting so the bus that was designed for 20 breakers but a 150 amp panel could actually handle 30 circuits but code limited the breakers so this was the cheat getting full use. This is how I remember it but may be wrong. when the panel has a listing like 12/20 or 30/40 the first # is the spaces 2nd circuits post CTL.
    – Ed Beal
    Commented Jul 8, 2020 at 22:48
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40 Amps. I've never heard those called "cheater" before - I think space saving is the term I've heard.

The total amps of all breakers in a panel often exceed the overall rating of the main breaker in the panel. The reality is that not all circuits are pulling anywhere close to 100% of their rating 100% of the time. Yes you can trip the main breaker.

The electrical service 125 Amps in your case is sized based on various factors. It isn't sized based on the breakers (though the breakers would be associated with the applicances/devices used to size the service). Here is an example online calculator that can help size the service.

http://www.douglashelmer.com/calculators/electrical/residential-service/index.htm

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  • So, would it generally be safe to replace one of the 15 amp ones with a 20 amp breaker? (again as long as the cable is 12 gauge, which it is)
    – Max
    Commented Jul 8, 2020 at 20:05
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    Cheaters was the original trade name as they were listed as non current limiting , they had no rejection feature so the buss locations could be overloaded tandem large breakers on both sides could do it. You can still find them on line today (non current limiting) stickers on the side.
    – Ed Beal
    Commented Jul 8, 2020 at 20:14
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    @Max -- you'll have to go through the entire circuit and make sure that the wiring's 12AWG
    – ThreePhaseEel
    Commented Jul 9, 2020 at 1:27

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