Tandem breakers


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Old 03-08-16, 02:10 PM
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Tandem breakers

In our panel we have a tandem breaker feeding a bathroom, one for lights and the other for a whirlpool tub. The panel is square QO40M200 which the manufacturer said will not accept tandem breakers. The breakers I use ate the qo plug in type. Am iok using another tandem breaker in this panel? If the breaker fits what is the issue with using them? Thanks.
 
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Old 03-08-16, 02:37 PM
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No it's not ok, and the one that's there should be removed. The breaker must have either been altered to fit the panel or someone installed a non-CTL breaker which are only for use in legacy (~pre 1970) panels.

The issue is that the box is only rated for 40 circuits and exceeding that limit overloads the box and violates the manufacturer's labelling.

The solutions in this case are to either double-up some existing circuits or add a subpanel adjacent to the main panel and move some of the circuits over to that.
 
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Old 03-08-16, 02:46 PM
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Those are Non CTL (Non Circuit Total Limitation) breakers. They can only be used in breaker panels made before 1965. The maximum capacity of your panel is 40 standard breakers as indicated by the model number, QO40M200. If it were rated for tandems there would be a four digit number indicating the number of spaces and total number of circuits. Example: G3040BL1200 = 30 spaces, 40 total circuits allowed. Up to 10 tandem circuit breakers can be used.

It is unsafe to use tandems in a panel not designed for them and probably their presence would be used by a fire insurance company to deny any claim. You need to add a subpanel.
 
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Old 03-08-16, 03:03 PM
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I figured this much...thanks for the info. How do I double up the breakers? And is this a safe practice? Pick two that are not used together or have small draws?
 
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Old 03-08-16, 03:11 PM
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Please fill in your location in your profile. If you are not in Canada you can connect two lightly used circuits to a pigtail and the pigtail to the breaker.
 
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Old 03-08-16, 03:15 PM
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With Q0 breakers you can attach two wires of the same gauge directly to the breaker lug*. If you pick two lightly loaded circuits, it is very easy to combine them in this fashion.

*Most other brands only accept one wire per screw, so the pigtail method is required.
 
 

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