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I'm finishing my attic and need to wire it (about 8 outlets and 14 LED recessed lights; also a half bath with GFCI outlet, fan, vanity light). I have gotten four electrician bids. Two said my existing 150 amp panel (installed in 1975) does not meet code and I need a heavy up to 200 amps. The third company said I just need a subpanel for the attic lights. The last one said my existing panel is fine.

I have attached photos of my panel. We will be adding two circuits (20 amp an 15 amp). Is it possible to tell from looking 1) whether it has the capacity for these breakers and 2) whether the panel itself meets code? The companies that said it needs to replaced told me that there is something wrong with the way the breakers are arranged.

Panel pic 2 enter image description here

  • Is there a breaker located elsewhere that shuts off power to everything this panel feeds? Or is this the only panel/set of breakers present? – ThreePhaseEel Jun 20 '18 at 23:23
  • Also, how much current does that rooftop unit actually pull, and likewise for the "attic condensor"? – ThreePhaseEel Jun 20 '18 at 23:33
  • Finally, how many branch circuits feed kitchen countertop receptacles? – ThreePhaseEel Jun 20 '18 at 23:35
  • I am not sure why this panel would not meet code it is a 150 amp panel with a 60 amp main breaker. Today's code requires a 100 amp for a single family or Multi family 60a is still ok and this panel meets that requirement, if there is a 100a main outside on the pole the wiring could be upsized to the panel. if there is no other disconnecting means the meter could be pulled wiring upsized new main installed but then the house wiring AFCI /GFCI requirements would need to be met and since this is a quality panel that is still made today the newer breakers could be installed. How many unused bkrs? – Ed Beal Jun 20 '18 at 23:53
  • I don't know of any other shutoff breaker. I don't know how much current the rooftop AC unit and condenser (in attic) pull. I also don't know how many branch circuits feed the kitchen outlets. – JCK Jun 21 '18 at 0:23
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You'll need to either change this out or fit a subpanel and separate main breaker

Your panel is of a mostly-obsolete configuration called a split bus panel that relies on the rule of six (see NEC 230.71 and 408.36) to turn off power instead of having a single main disconnecting means. This configuration (split bus with no single main disconnect) is no longer Code compliant, as it violates the provisions in NEC 408.36 Exception 1 that allow for rule-of-six panels to continue in service:

Exception No.1: Individual protection shall not be required for a panelboard used as service equipment with multiple disconnecting means in accordance with 230.71. In panelboards protected by three or more main circuit breakers or sets of fuses, the circuit breakers or sets of fuses shall not supply a second bus structure within the same panelboard assembly.

Furthermore, your panel violates the rule of six itself, as while the Code limits the number of handle throws needed to turn off power to six, your panel needs eight throws to turn off all the power (the 3 two-pole breakers need to be turned off, as well as the 2 single pole breakers immediately below the 2-pole breakers on the left, the single pole breaker immediately below the 2 pole breaker on the right, and both halves of the single pole tandem/double-stuff breaker top right).

As a result of this, while it appears you have slots available, between the twistouts with the "DO NOT REMOVE" labels on them and the rule-of-six issues, you have no usable spaces in your panel for what you want to do. The good news is that the breaker marked "main" on your panel only controls the lower bank of breakers (everything below the "main disconnect" labels), so while that lower bank can only draw 60A, the panel as a whole can draw the full 150A stated as your service ampacity.

While you're at it, you'll need to get rid of a few pieces of shelving

Some of the shelving surrounding the existing panel is problematic, too -- in fact, the shelves violate the NEC! (Betcha you never figured a shelf could violate electrical codes, huh?) In particular, you'll need to rip out the shelves above and below the panel, to about 8" from the edge of the panel each way, and preferably to 16-18" on at least one side -- on that side, you'll also want to trim the shelves in line with the panel back about 4-6".

This will rectify the ongoing violation of NEC 110.26(A) that exists with your current setup, as it requires an 78" high by 30" wide by 36" deep box in front of the panel, albeit not necessarily centered on it, to be kept clear so that neither you nor your electrician wind up swearing up a storm trying to work on the thing! (The shelving directly above the panel also violates 110.26(E)(1) as it would be considered "equipment foreign to the electrical installation".) Furthermore, the extra space off to one side provides room for a full-width subpanel to be fitted there, in case you go that route.

Now as to the details...

As I said earlier, you have two options to rectify this, namely:

  1. Replacing the panel wholesale with one that has more spaces (likely a 200A unit downbreakered to 150A to give you flexibility in panel selection)
  2. Installing a main breaker ahead of the existing panel and fitting a subpanel to provide the extra spaces needed.

Either way, I am going to assume that the 150A service is adequate (i.e. you don't need a "heavy-up" to 200A service). I can determine that given nameplate current ratings for the A/C units (attic condenser and rooftop unit), but for now, that's beyond the scope of this answer. (Provide it and I can add a section on the need for a "heavy up", or lack of need as the case very well may be.)

Replacing the panel wholesale

A 30-space panel, while technically not inadequate (if you could use spaces freely that is), is somewhat on the small side these days as branch circuits and electrical accessories proliferate and as AFCI requirements obsolete the use of tandem/double-stuff breakers. I recommend a minimum of 42 spaces with 200 or 225A bussing and a 150A main breaker field fitted to match the service size (putting a smaller main breaker in a bigger panel is fine as long as the panel can accept it, just like having fat wire on a small breaker is no big deal); if you can get such without too much additional cost (the parts price premium is somewhere around $100-$200), 54 and 60 space loadcenters are worthwhile to look into now that it's been a full decade since the 2008 NEC cycle removed the 42-circuit restriction on branch circuit (aka "lighting and appliance") panelboards. An added bonus to this approach is that all that will be needed for a "heavy up" to 200A will be running a fatter set of service wires and swapping the 150A main for a 200A one.

Fitting a subpanel

First off, in order to fit a subpanel alongside this panel, you'll need to do the extra shelf-trimming described above to get at least 16" (a full stud bay's worth) of space on one side of the existing panel that the subpanel can be mounted into.

From there, you or your electrician will need a suitable main lug subpanel and breakers to match (30 or 32 spaces/125A is the minimum I'd recommend here, but bigger is always better), a QO2125 125A, 2-pole breaker for the feeder breaker, some 1/0 Al XHHW-2 (say about 8-10' tops, so not much in the grand scheme of things), a RMC nipple of suitable size (preferably 2" trade size) to go through the stud between the two breaker panels, a second RMC nipple to provide ground between the new main breaker and the split-bus panel, and an enclosed circuit breaker (2 pole, 150A) to serve as a main breaker (I originally suggested a backfed main configuration, but the PK5RK hold-down kit required for that is incompatible with your panel.)

The new main breaker goes in-line with the existing main service-entrance cable -- it will be (with the power off) a "cut the cable and insert it in the middle" operation. The cable from the new main breaker to the existing panel gets stuffed down a conduit nipple connecting the two enclosures, and the bonding screw in the existing panel is removed as well as the neutrals and grounds in the panel organized properly (perhaps with the aid of a PK18GTAL or PK23GTAL ground bar kit). Finally, the subpanel is fed off the QO2125 using the XHHW-2 aluminum wire in the other RMC nipple mentioned.

  • This makes sense and explains why I need either a sub panel or heavy-up. Or, could I get a newer 150 amp panel? It’s going to hard to fit a 200 amp panel in the available space. – JCK Jun 21 '18 at 1:10
  • You can get a newer 150A panel, but that will limit you on breaker spaces -- how much room do you have above, below, and to each side of the existing panel? – ThreePhaseEel Jun 21 '18 at 1:20
  • It is surrounded by shelves so only about 12 inches on each side, 10 above, 3 below unless I tear out the shelves – JCK Jun 21 '18 at 1:25
  • How far is the bottom edge of the panel from the floor? This shelving may need a bit of surgery anyway, as right now it violates Code too... – ThreePhaseEel Jun 21 '18 at 1:29
  • @JCK -- boy, am I glad I asked! – ThreePhaseEel Jun 21 '18 at 1:45
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Well, it obviously met code in 1974 when it was last inspected, and so long as you don't change anything, it's still legal. The issue is, you are wanting to add a lot of circuits to this, and it appears to be a 60A main on a 150A panel. Nothing wrong with that and if your main breaker has not been tripping, I doubt that you need to upgrade the panel SIZE to 200A. You will however likely have to change that Main to a 100 or 125A though.

That "tandem" breaker on the upper right is likely the "code problem", combined with your new needs and the fact that to add circuits, you would need to replace several other of your standard breakers with tandems. Starting in around 1965 or so, breaker panels were required to be shown with "CTL" listings, CTL stands for "Circuit Tandem Limiting", meaning the restricted ABILITY to legally install those twin breakers, because the panel must be designed to LIMIT the total number of circuits the panel can have. Your panel is older than that requirement, so you cannot add tandem breakers to it now (other than "for replacement purposes only"), hence the electricians who want to replace it with a new panel, regardless of the size. The guys insisting on upgrading you to 200A are just looking out for your long term best interests by the way. It's not likely necessary, but it is a good idea if you can afford it.

As to the proposal to add a sub-panel, that too is a viable solution actually. If the existing panel has what are called "feed-through lugs" or the ability to add them, that would be ideal. Otherwise, you would have to remove two breakers from this panel and put in a feeder breaker to go to the new one, which means relocating the wiring for those two breakers to that new sub-panel too. If it were me, I'd go that way.

  • Thanks, this is all very helpful. Still confused about a couple things. 1) Do I only have 60 amps of power coming into my house right now? 2) Is there room to add any new circuits at all? If so how many? – JCK Jun 21 '18 at 0:14
  • I think the problem with this panel is deeper seated (it's a split bus unit with too many disconnect throws if it's a main panel) – ThreePhaseEel Jun 21 '18 at 0:19
  • @JCK -- can you edit your question to answer the comments I left on it? – ThreePhaseEel Jun 21 '18 at 0:19
  • The two companies who said I needed a heavy up said something about having breakers above where disconnects are (if I'm remembering correctly)--they said this was wrong. – JCK Jun 21 '18 at 0:25
  • @JCK -- I need to know the number of kitchen branch circuits (tip: plug nightlights into your kitchen outlets, and see which breakers turn a nightlight in the kitchen off when you flip them off) – ThreePhaseEel Jun 21 '18 at 0:27
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Here's the backstory on rule of six panels. Code requires that main panels have a main breaker. However, as houses got more electrical features and needed more power, Builders found out in a hurry that large main Breakers were expensive! They're still not cheap. So they worked a compromise, where they were allowed to have up to six main Breakers, each of smaller size, e.g the more affordable 60A. The rule is that you must be able to shut off everything with 6 breaker throws.

These panels have either 8 or 12 spaces in the main breaker area, intended for 4 or 6 2-pole Breakers. One of them, typically in the lower left, powers the built-in subpanel.

The six Breakers are intended to power large electrical appliances, or subpanels. And in a rule of six panel, they have a built-in subpanel right in the panel. This built-in subpanel is what is now outlawed. 6 main Breakers is still allowed. There are outlawed because electricians keep putting things there that don't belong there, like in your panel. Also because in a panic, people don't know which six Breakers to throw. Also prices of larger Breakers have fallen.

A subpanel

Typically when we see these, the subpanel area is full, and there are empty spaces in the rule of six area, or things that don't belong there. My view is the rule of 6 area is made for subpanel Breakers so fit another subpanel!

If nowhere else is suitable, then right next to the main panel. Right now, the subpanel area in your main panel is grandfathered, so it's legal to continue to use it. But in a perfect world, you could migrate everything out of it, and then you would be legal even by today's code.

The people who said this panel is fine are ignoring the rule of six, possibly because they don't understand it. I agree with their concept though, feeding a sub panel out of the rule of 6 area makes sense.

However, they should not be ignoring the fact that this will be a ninth breaker in the rule of six area, which is not allowed. They could fix that by swapping the double stuf breaker for a position in the lower area, giving four single Breakers in the Rule of Six area, and then replace those four with two 2-pole Breakers. A 2 pole breaker is allowed to power two unrelated 120 volt circuits, but it counts as a single trip.

Your panel would still be packed, however, which is why I would get ready to put a sub panel right next to the main panel. Double stuff Breakers can't carry you very far, since most new circuits require afci or GFCI, and those are not available in double stuff.

A new main panel

If cost is No Object, this is an Alexander the Great solution to this gordian knot. However, if space is a problem, you will be painting yourself into a corner again. A modern panel with a large main breaker is much more bulky, and will make your space problem worse. So you will need to find a way to deal with that gordian knot too.

There's one more potential gotcha. I posted a question about this, but you may need to replace all of your $4 Breakers with $40 afci or GFCI Breakers, since most circuits require those today. That would be the Lion's Share of total part costs. Although in a main panel swap the labor is also considerable.

  • Fortunately, fixing his 110.26(A) vio with the shelving will fix his space problems – ThreePhaseEel Jun 21 '18 at 22:53

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