Thread: # of breakers allowed in a panel box

I am pretty sure I know the answer to this but I just want to verify. How many breakers are allowed in a 200 amp box. Had 40 in yesterdays box, but 5 of them were double poled making a total of 45 throws in the box. I believe that this is incorrect. Thanks for your replies in advance.

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Originally Posted by william siegel

I am pretty sure I know the answer to this but I just want to verify. How many breakers are allowed in a 200 amp box. Had 40 in yesterdays box, but 5 of them were double poled making a total of 45 throws in the box. I believe that this is incorrect. Thanks for your replies in advance.

This is not a one size fits all.
The manufacturer determines what is allowable for each panel.
You can look up the manufacturers specs by model #

Yup, depends on the panel's label.

If it's a 40 space 50 circuit panel (40/50) you could probably do it. You have 40 spaces, so you could install 30 normal breakers and 10 tandem breakers for a total of 50 circuits, or throws.

I believe the panels made today will not allow tandems to fit if they are 20/20, 30/30, or 40/40, you would need a 20/40 or 40/50 panel... you get the idea...

Thing to watch for is modified breakers or other brands of breakers. You can fit different breakers in different panels, or adjust them to fit...

Originally Posted by Mike Kleisch

Yup, depends on the panel's label.

If it's a 40 space 50 circuit panel (40/50) you could probably do it. You have 40 spaces, so you could install 30 normal breakers and 10 tandem breakers for a total of 50 circuits, or throws.

I believe the panels made today will not allow tandems to fit if they are 20/20, 30/30, or 40/40, you would need a 20/40 or 40/50 panel... you get the idea...

Thing to watch for is modified breakers or other brands of breakers. You can fit different breakers in different panels, or adjust them to fit...

As was stated previously, prior to 2008 you could not have more than 42 poles. There were 20/40 panels and 30/40 panels, but I've never seen a 40/50 panel. I suppose it could be made, but it would have to be a relatively new panel.

In many panels you can look at the wiring schematic and see how many breakers are permitted. If there is no schematic then look at the model number (usually inside the panel, not on the cover). A 30 slot panel that can take 40 breakers usually will have 3040 in the model number. You may also bee numbers like 1224, 2024, 2040, etc. First two digits are typically the number of full size slots and second two the number of total circuit breaker poles.

It doesnt matter anymore, the 42 circuit rule has been eliminated. Up in Canada 60 circuit panels are the norm. However, make sure the breakers are the same brand as the panel.

All older panels have a maximum rating of spaces/breakers listed on the panel print. From a technical perspective it is a violation if this panel isnt listed for 40 circuits, however if the breakers are listed for the panel it is not really a hazard.


One thing to keep in mind, some tandem and quad breakers have rejection tabs/hooks/notches to prevent someone from placing more than the rated # of breakers in a panel ie a 40 space panel could end up with 80 circuits. If these breakers are of the rejection type make sure no modifications have been made to them so they fit.

Originally Posted by Mbrooke

It doesnt matter anymore, the 42 circuit rule has been eliminated. Up in Canada 60 circuit panels are the norm. However, make sure the breakers are the same brand as the panel.

All older panels have a maximum rating of spaces/breakers listed on the panel print. From a technical perspective it is a violation if this panel isnt listed for 40 circuits, however if the breakers are listed for the panel it is not really a hazard.


One thing to keep in mind, some tandem and quad breakers have rejection tabs/hooks/notches to prevent someone from placing more than the rated # of breakers in a panel ie a 40 space panel could end up with 80 circuits. If these breakers are of the rejection type make sure no modifications have been made to them so they fit.

It does matter, because the 42 rule was eliminated for panels manufactured after approx. 2008. The rule still applies to older panels.

All breakers made for CTL panels should not fit if not designed for the panel, but as you stated some electricians (or others) modify them to fit. Also, places like HD probably sell tons of non-CTL breakers that should only be used in pre-1968 panels. It seems like nobody pays attention to that. Many electricians I have talked to don't even know what a CTL panel is.

It depends on how the panel is being used (service equipment or not) and if mfg prior to 2005 NEC, if it is a power panel or a Lighting & Appliance Panelboard, and if it is a MLO or MB panel (or in the case of aa L&APB if it has two Mains breakers), or if older panel if it is split bus and being used as service equipment; all dependant on the date of manufacture, the listing, and the listed labeling on the enclosed panelboard - the wiring diagram and limitations and instructions on the labeling are the ruling factor in addition to the application conditions (if they meet or not). Bus Stab ratings and values cumulative and individual) if limited by the labeled insructions may further restrict. Poles and stabs; throws is a different rule for Disco's for MLOs or mains for a L&ABP.

Originally Posted by H.G. Watson, Sr.

It depends on how the panel is being used (service equipment or not) and if mfg prior to 2005 NEC, if it is a power panel or a Lighting & Appliance Panelboard, and if it is a MLO or MB panel (or in the case of aa L&APB if it has two Mains breakers), or if older panel if it is split bus and being used as service equipment; all dependant on the date of manufacture, the listing, and the listed labeling on the enclosed panelboard - the wiring diagram and limitations and instructions on the labeling are the ruling factor in addition to the application conditions (if they meet or not). Bus Stab ratings and values cumulative and individual) if limited by the labeled insructions may further restrict. Poles and stabs; throws is a different rule for Disco's for MLOs or mains for a L&ABP.

That is probably all true. However, from an inspection standpoint, it comes down to this:

If its an older panel and there are more than 42 CB poles its probably wrong.

If there is a wiring schematic showing where twins can be installed and there are more than permitted or they are in the wrong slots it is wrong.

If twin/tandem breakers are in a CTL panel and they are labeled as "Not for use in a CTL panel" it is wrong.

If there are twin/tandem breakers and the model number does not include something like 1224, 2024, 2040, 3040, etc. it is probably wrong.

I believe that I can tell most of the time whether twin/tandem breakers are correctly used.

Otherwise, you can take the approach used by many inspectors: "There are double taps in the panel. I recommend further evaluation..." (BTW, I know double taps have nothing to do with twin/tandem breakers, but it seems that this is the approach to inspecting panels that I see many times, even when there are many more things wrong in the panel).

Thanks for mentioning buss stab rating H.G., this one is often overlooked especially when used as a feeder to a sub panel.

I don't mean to be dumb here, but I need help. How do I start a new thread with a new question? I have an electrical question about the requirement for GFCI plugs and Home Sewage Treatment systems. Thanks for everyone's patience.

Dave
Caldwell Home Inspections, LLC.

Originally Posted by Robert Meier

Click on this Electrical Systems: Home Inspection and Commercial Inspection. Next click on the blue oval that says + Post New Thread.

Thank you Sir.