MWBC and GE Spacesave dual-pole breaker spanning over different pole/phase

Question

I have 3 multi-wire branch circuits. And two of the 3 set of MWBCs were each put on same phase. An oerloaded neutral has occurred on one MWBC. (It was actually the case of oxidation, not overload, resulting in a smoldered switch box, but the glaring issue of overloaded neutral remains).

It has been cleaned up, but not powered up nor box-packed yet. I have to reposition breaker feeds to ensure that dual-pole having different phases (240VAC on both red/black hots of each MWBC legs) truly occurred.

Much time was spent reidentifying the matching pairs, matching 3 red wires to their corresponding 3 (out of 14 black wires at the panel. They entail popping many coverplates and identifying red wires. Whole house electrical plan was drawn.

Re-paneling is not yet an option yet, but remains a long-term goal (we are getting a swimming pool).

Now it comes the time to reshuffle MWBC wires around at the panel so that each MWBC red/black can be resleeved using hand-noted leftover Romex covering. And to pair them up to a switch being next to each other, but using different phases in order to achieve this true 0VAC neutral (and not the double-amped overloaded neutral like I experienced when fed with same-phase).

A double-pole (that tosses both side of one MWBC off at the same time) is the safety goal here and focus of this question.

This old house has a GE TX1612 (Rule of Six, split) panel. Took awhile to master the pole arrangement.

What I am unclear on is can I position a double-pole handle-tied switch to span over different phases, using a GE Spacesaver breaker?

Assuming slot 10 is fed by phase A. And slot 12 is phase B.

GE TX1612

Perhaps a GE THQP double-pole (handle-tied) 15A and strategically insert it to span across slot 10 and 12 for both-phase coverage for just one MWBC leg? Was looking at simplybreakers.com/products/thqp215 If so, this panel could support up to 3 MWBCs on one side. And gain benefit of electrician safety when turning one MWBC leg/dual-feed to off position.

Or is this CTL meaning to have some kind of guide/notch/peg that may prohibit such spanning of phases by such a dual-pole breaker?

Answer 1

can I position a double-pole handle-tied switch to span over different phases, using a GE Spacesaver breaker?

Actually, it's mandatory.

NEC 110.3(B) requires you follow instructions and labeling. That for the 2-pole thin breakers will require you to place it spanning two breaker spaces e.g. 9-11 or 18-20 in your panel. (which has weird numbering because of the Rule of Six area).

The breaker should have some of physical reject feature to make it impossible to land it on same-phase (e.g. 7-9). However people mess this up a lot so I suspect the reject feature is a flimsy piece of plastic easily broken.

Or is this CTL meaning to have some kind of guide/notch/peg that may prohibit such spanning of phases by such a dual-pole breaker?

Oh, GE has an ingenious way of keeping you honest regarding CTL. Look close at the bus stabs - they're not normal. Everyone else's bus stabs look like a minus sign. "--". On GE, where tandems are allowed, they have a little "two-barred cross" like the flag of Slovakia "++". The double-stuff breakers clip onto the side bars not the normal stab.

If you try to put a double-stuff where GE doesn't want you to, it simply falls out. There is nothing for it to clip onto, the cross isn't there. For instance in your Rule of Six area up top, the stabs probably look like this "+-" with no cruciform on the right side.

This means you can't mess up.

By the way, feel free to enlarge the "Lighting Main" breaker to 100A. It's authorized to 100A; the reason they gave you 60A is the entire point of Rule of Six that breakers larger than 60A were very costly back then. They're not now.

As a Rule of Six panel you must respect the NEC Article 220 Load Calculation; this is the only thing preventing your panel from overloading. If you were to replace your meter pan with a meter-main, then the Rule of Six would no longer apply.