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I installed a Siemens QT (2) two pole quadbreaker into my panel board. All 4 circuits go to the same location. The inner two breakers and outer two breakers are common trip. However due to my setup I would like all 4 breakers to trip if any single circuit breaks. I know they have tie down bars but cannot find one for a quadbreaker. Not to mention I will have to cut the existing common trip bars off. Is this safe and is there a correct way to do this. People on reddit told me to use a nail stuck through them all. However I don't think nails are UL listed ;) Below is an image of the exact breaker I used. Any input?

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  • Just what the heck are you feeding with this weird setup?
    – ThreePhaseEel
    Commented Dec 27, 2016 at 23:16
  • Also, do you have spare slots in this panel to play with, or are you running out of slots already?
    – ThreePhaseEel
    Commented Dec 27, 2016 at 23:17
  • I am out of spots in the breaker box. Also because of the need for phase cancellation on a shared neutral on a MWBC I was forced to use a quad breaker. There is a tandem breaker on the other side of the box that has one side not being used. So I guess there is a spare spot...
    – Dylan
    Commented Dec 28, 2016 at 0:37
  • I am feeding large power tools, ventilation, A/C, space heaters, fans and many other things I am forgetting to mention
    – Dylan
    Commented Dec 28, 2016 at 0:44
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    Sheesh -- sounds like you should put a subpanel in instead of having all this crap dangled off a single quadruplex breaker!
    – ThreePhaseEel
    Commented Dec 28, 2016 at 1:16

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Don't improvise.

A breaker is a combination of an overcurrent detector and a switch, with a motor mechanism which causes one to throw the other. The motor mechanism is passive; it is a spring.

Each single breaker has enough motive power to throw its own switch, and also its partner switch.

It does not necessarily have enough motive power to throw four. You could have a horrible situation where none of the breakers trip because the other 3 are preventing the first's mechanism from operating.

You should not improvise such a thing. Contact the manufacturer for advice.

Can you live with three?

They may make 3-phase breakers for your style of panel. Obviously they are designed for phase A-B-C, but they will work fine with phase A-B-A which is what would happen if you put that breaker in a 120/240 split phase panel. Don't share the neutral!

They will not be duplex/double-stuff breakers, however.

Or use shunt trip breakers with a SCADA system

It's a "cost is no object" option, but it'll work. Most makers produce a "shunt trip" breaker - which gives you a 24-volt pigtail. Applying 24 volts causes the breaker to trip. Square D HOMeline probably doesn't offer one, but Eaton CL is UL-classified for that panel.

So now you have a supervisory device that works one of two ways: Either it listens for a breaker tripping (hot goes away) and shunt-trips the other 3 breakers. Or, it monitors the underlying conditions you are concerned about and trips all 4 breakers if programmed conditions are met. This is easy peasy with a simple Arduino or any other hobbyist-tier process control system. Rather than have the Arduino throw the 24V, you have it throw a 5V relay which throws the 24V. 24V can be sourced from a $15 thermostat transformer located in a panel knockout.

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  • The comment about the single breaker not having enough motive power to throw the other 3 is a great point I had never even considered. I knew I was smart to ask you guys. Unfortunately I need 4 circuits. But I will contact Siemens like you recommended and see if they have any recommendations. Out of curiosity why then do they sell tie bars for breakers given this information?
    – Dylan
    Commented Dec 27, 2016 at 23:52
  • Try it. You'll probably find the listed handle-ties are designed so they can't stack.
    – Harper - Reinstate Monica
    Commented Dec 28, 2016 at 0:09
  • If one circuit is auxiliary (Not likely to be the one that initiates the trip), it can be fed through a relay powered by one of the other three.
    – Harper - Reinstate Monica
    Commented Dec 28, 2016 at 0:11
  • Oh no I don't want to try it. You are right it doesn't seem wise. What do you mean it can be fed through a relay? I was maybe going to try to figure out something "post-outlet" to turn everything off if something fails. Basically I have 4 circuits. Circuit 1,2 and 3 do all the work and generate all the heat. Circuit 4 handles cooling. If 1,2 or 3 fails I would prefer that everything else keep running. However if 4 trips I want the rest to turn off. Are they devices for this?
    – Dylan
    Commented Dec 28, 2016 at 0:16
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    @Dylan -- a-ha. It sounds like you don't want all four trips commoned together after all, but an alarm contact + a shunt trip that causes the cooling zonking out to trip out the rest of the stuff. (Maybe we can find a way to wedge a temp sensor in as well, so in case the cooling mechanically dies but doesn't trip the breaker, the rest of the stuff will get depowered before crap gets super-stuffy)
    – ThreePhaseEel
    Commented Dec 28, 2016 at 1:19

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