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I want to add a 240v breaker at the main panel for a small garage AC that will go right next to it. There isn't a main breaker though and I assume this is still rule of 6 compliant hence so but just want to confirm.

I assume I either need to call for a disconnect or plug in the new breaker while disabled but live.

Seem about correct?

(House built in ~1995 in Texas)

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4 Answers 4

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Yes, this is a rule-of-6 panel. You don't need to turn off the power to install a new breaker. Just make sure the breaker you're installing is switched off.

Note that what you are doing likely requires pulling a permit, and the inspector may require you to upgrade the panel to include a main breaker or add a disconnect upstream of that panel.

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    And make sure there are no oops. Oops need a second person to call 911.
    – crip659
    Apr 17 at 20:51
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    Thanks for this and haha on the oops. Will try my best not to slip. Just going to hunch that hole out of the right side and secure a waterproof connector housing in for the split ac going in.
    – RJ44
    Apr 18 at 3:13
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Another option for rule-of-six compliance is to handle-tie breakers that have no other reason to be handle-tied, as that makes two breakers one "motion of the hand."

So, not a double, not an MWBC, not serving devices on the same yoke - just to reduce the number of hand motions to shut everything down.

But in this case you have 4 motions of the hand now, so adding one more only makes 5.

Personally. I'd be very much in favor of adding a disconnect switch here. Which might look like swapping to a panel with a main breaker (and one with the insulated covers over the feed lugs, so those are not waiting to bite you.)

Working in a panel like this where the bus bars are always hot and the feed lugs are exposed, you have to be absolutely, positively sure that nothing slips (or is otherwise misplaced for any reason, such as forgetting for 5 seconds, answering your phone, sneezing, getting stung by a wasp...) in a way that ends up with a body part or a metal tool contacting any of the parts that are always live, and effectively unfused (there's a fuse/breaker somewhere up the distribution system, but it will supply enough power to vaporize the tool and parts of the panel if you screw up. Spraying you with molten metal and extremely bright light.)

What that means in a practical sense is that your instinct to call for a disconnect is the correct choice here, as you don't have and can't afford an arc flash protection suit. Nor do you have training or experience working in a live panel, which puts doing so well in the "hold my beer and watch this" category. It's one thing when you have a main breaker and only have to avoid the feed lugs - with the insulated covers for feed lugs required by current codes, it's not very hazardous to work in such a panel. These old things are different in important but subtle (they look mostly similar) ways.

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    My power company does advertise/mention that they have a once a year free disconnect service. Being free and making you safe seems like a good deal.
    – crip659
    Apr 18 at 14:22
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    From what ive read, the issue isnt really getting the power off, its getting them turning it back on when all you did was add a breaker... that seems like such a pain.
    – RJ44
    Apr 18 at 16:07
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Here's the thing with Rule of Six panels.

The sum of the breakers is allowed to exceed the size of the service.

However, the loads are not allowed to exceed the service! So you must do a thing called a Load Calculation, NEC 220.82, useful and accurate worksheet here, and affirm that all the loads you are planning will not overload the service.

You must do this every single time you add a load other than a casual 120V plug-in load to the service.

The panel is a 12-space GE, and accepts either the normal THQL or thin THQP breakers. You're only allowed to put 6 breakers in it, unless you handle-tie as Ecnerwal suggests.

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Yes, that is Rule of Six compliant.

However, I question whether any half-size breakers should ever be used in that panel. A 12-space panel is ideal for Rule-of-Six because when used with full-size double breakers, there is no possible way to violate the "six throws" requirement. As it currently sits with several half-size breakers, you have 4 throws already and could easily add 3 more full-size double breakers and end up with 7, which would violate Rule of Six rules.

I suspect that the panel is designed to also be usable as a typical subpanel, so it may well be designed for use with half-size breakers. But when used as a main panel that does not make sense.

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