Electrical – How are tandem breakers used in multi-branch circuits

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I'm in the process of replacing my breaker panel. I was talking to my neighbor and she said that her panel was changed when she did some remodeling. I was interested to see what was installed in her condo because we have a limited width (11in) space for the panel. Here is a picture of her panel (the one with the 30A breaker) and mine (the one with the 40A breaker). It looks like all of her breakers (except for the 30A) are tandem (Type MH-T on the labels). The installation was done by a certified electrician and inspected/approved by the
city. I have two multi-branch circuits in my condo. You can see breakers 4 and 5 linked with a piece of metal. Breakers 2 and 3 are also multi-branch but the metal link is missing. Her condo is like mine so she should also have two multi-branch circuits. So … how did the electrician do that with the tandem breakers? I'm trying to fill the missing info I have in my knowledge because my ignorance says what the electrician did is wrong.

BTW it also looks like the A/C breaker was downgraded from 40A to 30A. I measured the current in the A/C in my unit and the running current is 18A so I thought I could do that but I was discouraged from doing that (in another post here) because of high current at start up, which made sense.

I could think of a weird way of using tandem by connecting one to one pole and another to another pole and butting them together and connecting them with a metal rod but …now that would be streching the rules, wouldn't it? and something I wouldn't do myself but would it be legal? Anyway I don't see any metal rods connecting her breakers.

Thanks

neighbor
mine

Best Answer

By "multi branch circuits" you mean multi-wire branch circuits or MWBCs.

How do MWBCs and tandems go together? THEY DON'T.

Either

  • the electrician ran new wire, eliminating the MWBCs, or
  • he carefully placed them on opposite poles (you have to know how to do that) and totally ignored the Code requiring handle ties, and is just hoping the next guy doesn't carelessly rearrange them onto the same pole, or
  • he slapped them on a tandem and the neutral wire is glowing cherry red right now.

If you want to do that same thing, your best bet is to put both pairs of your MWBCs onto a 2-pole/2-pole quadplex. That's what he should have done.

Making your own handle tie is out of the question. Listed handle ties arent available for duplex breakers, but they don't need to be, since quadplex breakers are readily available.

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