Does the arrangement of breakers within a panel matter or follow any rules?

Question

When somebody is installing breakers initially or doing a major remodel, are there rules or restrictions that must be followed in regard to which breaker goes where in the panel spaces?

Obviously dual-pole breakers need to be installed into a spot where they can reach both phases, and any other instructions on the panel labeling must be adhered to. But beyond that, I'm curious if any of these considerations matter or are stipulated in code:

• Locate largest rated breakers closest to the main, and 15A circuits farthest away.
• Balance (within some threshold) the total breaker ratings on one phase with the other one.
• Balance the expected real-life load on each phase. (Is there even a way to calculate that?)
• In specific locations (e.g. the two separate kitchen countertop receptacle circuits) put these two circuits on different phases -- if the circuits are not wired as an MWBC.
• Group standard, AFCI, and DFCI breakers together.
• Group breakers by the rooms they serve, or by circuit type, or by 120/240V, or...

Put another way, if somebody were to pop all of the breakers out of their panel (without unscrewing any of the wire terminals!) and shuffle them all randomly, would they need to apply any sort of code interpretation or common sense to reinstall them correctly?

Answer 1

While we're discussing bad technique, let me hit the awful practice of "Mister Snippy", snipping the wires short so they can only reach the breaker they're on right now (or the neutral bar). Mr. Snippy thinks he's impressing the inspector with wild overinterpretation of NEC 110.12. Actually they're dooming the panel to a bad hair day of wire nut extensions, when changes inevitably need to be made later.

Locate largest rated breakers closest to the main, and 15A circuits farthest away.

This is a very bad idea for two reasons. First, as Jeff Wheeler discusses, you're dancing with the devil on Stab Limits. I recently saw a panel with a 40/40 quadplex across from a 30... and the OP wanted to change the 30 to a 30/50. If you don't see a problem there, read Jeff Wheeler's answer.

So the idea of crowding the biggest up top, abeam of each other, is a terrible idea.

Second, about three 2-pole double-spaces should be "reserved" if you will, for things that actually have a need to be there -- generator interlocks (particularly "across" interlocks such as Siemens ECSBPK01), surge suppressors, solar, that kind of thing. I'm not saying "don't use them", but anything you put there should be easily moved. A second warning to Mr. Snippy.

Balance (within some threshold) the total breaker ratings on one phase with the other one.

The trip value? Pointless. No gain to it. Prioritize other things.

Balance the expected real-life load on each phase. (Is there even a way to calculate that?)

That makes a lot more sense. You just have to think about how houses are being used. You don't run the dishwasher while you're preparing a meal for instance.

In specific locations (e.g. the two separate kitchen countertop receptacle circuits) put these two circuits on different phases -- if the circuits are not wired as an MWBC.

Yup, or "saw and dust collector".

Group standard, AFCI, and DFCI breakers together.

Unconstructive and useless. I see it sometimes, but that's just pandering to 110.12, trying to make a panel that looks neat for no good reason.

Group breakers by the rooms they serve, or by circuit type, or by 120/240V, or...

I think the best question to be asking is, "how do I best facilitate people finding a breaker they're in a hurry to turn off?" That being the reason they have switch throws instead of just reset buttons.

Answer 2

You need to read the specifications for your panel. Almost all panels have a bus stab limit that is lower than the total panel capacity. Not all stabs are created equal -- the panel might allow higher-amperage breakers at the top or on one side.

Here's a picture from my last home. Note my 200A panel allows 100A circuits on the left but only 70A circuits on the right.

Answer 3

The panel makes the rules

Beyond the NEC 210.4(B) call for common disconnect (i.e. an identified handle tie or multi-pole breaker) for multi-wire branch circuits, the old "rule of six" for service/structure disconnects, and the favorable treatment NEC 705.12(B)(2)(3)(b) gives to "opposite end" solar/DG feed-ins, the layout of breakers in your panel is determined by the panel's own labeling and specifications. In particular, at least for the residential meter-main and loadcenter hardware I've seen documentation or labeling for:

• Loadcenter bus stabs have a limited ampacity as was mentioned in the other answers, and on many panels, this ampacity can be less than the busbar (some Siemens meter-mains have 70A stabs on a 200A buss!)
• Even if you don't have to contend with bus stab restrictions, it's possible to be restricted in what circuits go where due to limits on wire bending space within the loadcenter. This is a common issue with meter-mains, especially those using more compact designs (EUSERC column width units are really bad about this)
• Many panels are very limited in what positions (usually, the top leftmost spaces, sometimes the top rightmost as well) can accept the retainer kits used to backfeed a breaker, say if you are fitting an interlock kit for a generator or downbreakering a panel below what its main breaker frame size has available
• Some panels are still Circuit Total Limiting and can't accept "double stuff" breakers in certain spaces, although this is going away slowly due to the 2008 NEC's removal of the 42 circuit hardcap on panelboards.
• Single-main or remote-main (i.e. main lug) split bus panels are still legal (as the rule of six doesn't come into play any longer) and available (as "generator loadcenters"), and these impose additional constraints, up to and including the secondary/standby interior having a lower ampacity than the primary interior (as is true for the Siemens generator panels)
• Some breakers simply won't physically fit in some panels, even if they are otherwise listed for use in that loadcenter line (Siemens QN, Eaton BJ, and GE TQDL breakers generally do not fit into column-width meter-main interiors due to their side-by-side "double frame" construction, for instance)
• Some panels may have restrictions on usage for auxiliary main disconnects or similar facilities -- you can't use the solar input space on Siemens solar-ready meter mains to feed a load for instance, as that's a labeling violation

Answer 4

Essentially the concept is to avoid heating the buss. So high demand loads (meaning - amp draw / frequency of use / duration) should go closest to the main breaker or main lugs. If they are are installed at the farthest location from main lugs or breaker then the entire buss length is heated and every breaker in between adds to the heat load. Whereas when high demand breakers are positioned close to main, the lower current draw breakers are not overtaxing an already (possibly) 'warmed' buss with their lesser need.

Answer 5

There really isn't a code issue on where to install various breakers, but most of what you said is a preference. Best practice is to install the highest rated breakers as close to the main as possible. Other than that, its mostly a preference.

On your 4th bullet point, regarding putting kitchen circuits on different phases is a good idea, "unless a MWBC". Given your obvious knowledge expressed in the rest of your post, I'm thinking that's a typo. A MWBC MUST be wired to opposite phases.

One more thing: bear in mind that each phase in a 200 amp panel can supply 200 amps. (edited from previous error). So even if all kitchen circuits were on the same phase and you were running a toaster, waffle maker and coffee pot at the same time, you'd only be drawing about 30 amps. Sure, it's a good idea to put the kitchen circuits on separate phases, but don't worry too much about it or over think it.