Why might my 2001 house not have a main breaker, and how big should it be?

Question

(My house is in Texas, built in 2001.)

Today I was outside inspecting my electricals -- as one does -- and I was surprised to see that there is no main breaker installed in my primary breaker box.

Now, there is a punch-out spot for a main breaker, but it is vacant (and not punched). Below it are 4 breakers (are these called "branch circuits?") for:

• dryer (30A)
• subpanel (60A)
• a/c (60A)
• unlabelled, but by process of elimination: oven (50A).

This primary panel is on the exterior of my house, and is fed by short conduit from the meter base directly next to it. The power service comes in from underground, directly up into the meter base (which is sealed w/ a serial-numbered tag.) There doesn't seem to be anywhere else that the main breaker could be.

1. Why might this 2001 residence not have a main breaker? Was this ever to code?

2. How could anyone safely service this primary breaker box, unless they first schedule the electric company to come out and yank the meter or otherwise disconnects service?

3. If I were to have a main breaker added, what amperage should I get? I don't know this 100%, but I assume based on my appliances, usage patterns, and the fact that I have a "CL200" meter that I have 200A service. However, there are a few puzzling details about this primary breaker box that raise some doubts:

• The manufacturer's sticker says that if someone was to remove the main breaker, that they should fill the hole with cover "QOM1FP", which hints that the size of breaker that fits that hole is a QOM1 form-factor. From googling, it seems like that form-factor tops out at 125A.1
• I think I've read that the main breaker doesn't have to be as large as 200A just because your branches sum to 200, but even still 125A seems low, all considering. I have certainly run my dryer, A/C, dishwasher, oven and sundry appliances all simultaneously, and 125A seems like I'd be asking for trouble, if they had bothered to put in a main breaker that could fit this panel.

4. Does the above imply that, if I wanted to add a sane main breaker, that I'd need to have this main panel upgraded? The panel, model "40265-765-01", isn't searchable on SquareD/Schneider's website anymore.)

1 For QOM1 amperages, see https://stevenengineering.com/wp-content/uploads/2019/02/45CBMCC.pdf

UPDATE: a respondent has suggested that I upload a picture of the panel:

Answer 1

As Manassehkatz discusses, this is a "Rule of Six" panel. In the literal way - this panel is up to six breakers (no more allowed) with no main.

The normal arrangement for Rule of Six is that 1 of the breakers powers a subpanel which contains all the other loads in the house. There's a name for that breaker, the "Lighting Breaker", and the subpanel is called the "Lighting Area". (particularly on split-bus panels, which have both the Rule of Six main panel and the Lighting Area subpanel in the same enclosure.)

How could anyone safely service this primary breaker box, unless they first schedule the electric company to come out and yank the meter or otherwise disconnects service?

Consumer-tier panels other than Pushmatic all are "plug-on", and it's easy to install the breakers with the main bus power on (but breaker off). 1) attach the wires, 2) hook the heel of the breaker into the rail, 3) push it onto the bus stabs. Any qualified person can easily handle it.

If I were to have a main breaker added, what amperage should I get? I don't know this 100%, but I assume based on my appliances, usage patterns, and the fact that I have a "CL200" meter that I have 200A service.

CL200 implies a rating of 200A. Likewise, VR-rated street tires have a rating of 130 mph, but the cop explained to me that's a maximum, not a requirement :) So all we know for sure is that if that box were used in a 200A service, it would be alright.

You would need to consult the power company to ask what service size they think they are giving you, which will be based on the size of your service drop wires and their connection back at the pole. Their service wire may not be ready for 200A!

Does the above imply that, if I wanted to add a sane main breaker, that I'd need to have this main panel upgraded? The panel, model "40265-765-01", isn't searchable on SquareD/Schneider's website anymore.

Not everything is on the Internet. The way you determine the correct main breaker for that panel is by contacting a Square D dealer. This is generally an Electrical Supply House. Square D may also answer the phone if called. They continue to make retrofit main breakers for panels no longer offered.

The manufacturer's sticker says that if someone was to remove the main breaker, that they should fill the hole with cover "QOM1FP", which hints that the size of breaker that fits that hole is a QOM1 form-factor.

My feeling is that it's likely that a main breaker is available. Whether it goes above 125A I don't know, but nothing would surprise me.

I think I've read that the main breaker doesn't have to be as large as 200A just because your branches sum to 200, but even still 125A seems low, all considering.

You're correct that panel breaker sums can exceed (or wildly exceed) main breaker rating.

Is that sufficient for the load to be served? That is adjudicated in a simple way, and on a Rule of Six service, this method is mandatory with each load change. This is called a NEC Article 220 Load Calculation. It takes your square footage, the number of kitchen and laundry receptacle circuits, and the rating of large 240V and fastened-in-place appliances. It applies some fudge factors to reflect collected data and the fact that a little overload is tolerable for a short time.

With a Rule of Six service, this Load Calculation must be re-computed anytime a load is changed. The Load Calculation is the only defense against overloading the panel. (which is why Rule of Six "as a substitute for a main breaker" was banned - no one was revisiting the Load Calc, and panels were being overloaded).

Anyway, to answer your question, the Load Calculation will tell you whether any given service size is adequate for your house.

Does the above imply that, if I wanted to add a sane main breaker, that I'd need to have this main panel upgraded?

Not at all. Thanks to NEC 2020 now requiring outside disconnects, a new product is popular: The Meter-Main. This is a meter pan with a built in main breaker. You could swap your meter pan for a meter-main, and just like that! The Rule of Six is extinguished for that outside 4-breaker panel, and you can populate it with as many breakers as you like.

Note that the panel cover has 16 twist-outs, but behind that, expect only 12 spaces to actually exist and have a working bus. They use the same deadfront (bolt-on cover) for both 12 and 16 space panels.

The Load Calculation is still required for any large load changes. Just now, the main breaker is one layer of protection against bungles in this area.

Answer 2

You probably have what is called a Rule of 6 panel. These were extremely common in the 1950s and 1960s, because large (e.g., 100A) breakers were relatively expensive but houses were starting to need more power for air conditioning, dryers and other large appliances. The basic concept is that you would have no more than 6 things to turn off (fuses to pull or breakers to flip) in one location. Generally that would be a few large appliances (e.g., dryer, air conditioner, oven) plus one 60A (or possibly smaller) catch-all that would take care of all the smaller appliances, lighting and general use receptacle circuits. In fact, many panels were designed with all of this in one panel - 6 large breakers up top, one of which fed the equivalent of a subpanel in the bottom.

The only strange part about this is that by 2001 it was quite common to have a single large main breaker. My hunch is that in your area, at that time, Rule of 6 was still allowed, but for practical ($$$ usually) reasons the builder used a small regular panel ("lug" rather than "main breaker", but capable of adding a main breaker) plus a subpanel instead of putting in a large panel with a main breaker.

To your questions:

1. Yes, this was code at one time. Was allowed in 2001 for new construction? I don't know.

2. Yes, servicing this safely would require cutting the utility power first. But since most (numerically, not kW) loads are in the subpanel, that isn't much of an issue.

3. 200A is plausible, but that is really a question for your utility. Unlikely to be more than 200A, but it could be less. Any change must be coordinated with the utility for safety, of course. (And if you upload a picture of the panel, the experts may be able to figure out a little more.)

4. Can't say without more details.

Update: The box, and dead front, appear designed for a 16-space main breaker panel. But the label is the key. The label shows just 12 spaces in use, which just so happens to be enough space for 6 double-breakers. Which is what you normally have in a Rule of 6 panel.

Conclusion: Rule of 6, panel, but manufacturer decided it was cheaper to use the 16-space boxes for what are effectively 12-space panels. Possibly because by 2001 a Rule of 6 Panel would be rated for at least 125A and very possibly 200A service, so it would not be a tiny "little" 12-space panel. It is often less expensive to include more metal than to manufacture truly different items.