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This is a follow up to Why does a single pole tandem breaker allow connecting the switch handles? which was asking what circumstances handle-tied tandem breakers would ever be useful. (There are some good reasons.)

Some answers to that question raised the issue: is it actually "permissible" to tie two QO tandem breakers together yourself? Such as a QOTO2020.

By permissible I mean: strictly allowed by the manufacturer & therefore to code. (I'm sure you could rig something up but if you want to do it by the book & know that it is safe, that may not cut it.)

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This is OK, as the manufacturer has a specific part for this job

Handle-tying the two inner half-breakers in a pair of (modern style) QO tandem breakers is legal, no different than handle-tying two full-size breakers save for a change in part number: instead of a QO1HT (the normal QO handle tie), you need a QOTHT instead (image from Square-D's product page):

QOTHT picture

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The information I have been able to find seems inconsistent / incomplete.

For QO breakers there is a handle tie from the manufacturer (Square D / Schneider Electric), which is part QO1HT.

enter image description here

However the documentation is sparse and doesn't state which specific breakers this is meant for. I was expecting an exact listing, much like you would see for a panel calling out which breakers you could use.

A catalog document does state "Converts any two adjacent 120/240 Vac 1P QO circuit breakers to independent trip 2P. " Based on that you might assume its OK to use their handle tie with any single pole QO breaker. But there is contradictory information. At least I found a comment posted by the manufacturer to a customer question stating:

From SchneiderCustomerCare:

April 27, 2016

...the QO1HTCP is only for the QO load centers. We offer the HOM1HT for the Homeline. However neither will tie Tandem breakers together. We do not offer a breaker tie for your requested application.

(source)

(Not sure why they use a slightly different product # in that comment, though it seems like the same thing. Might be because it is sold in a qty > 1).

So if in doubt, probably a call to the manufacturer would be in order.

And though this is just about QO breakers I'd be circumspect about any brand / model unless the instructions are crystal clear.

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  • The part you're after is a QOTHT – ThreePhaseEel Oct 8 '19 at 11:43
  • QO handle ties are used on breakers that are on adjacent poles. Square D only has 1 quad that I can remember it is a 20303020. This provides a 30 amp double pole and 2 single 20’s in 2 standard slots using the handle tie. Get prepared for some sticker shock these are spendy. But the ties are listed for use on adjacent poles, I don’t think you could even force them into a parallel tandem. They used to make inline tandems I thought they were better but you don’t see them anymore. Where are these used, multiwire branch circuits , or any place a common trip was not required. – Ed Beal Oct 8 '19 at 13:54
  • @EdBeal -- the QO20303020 is the only packaged kit for quadplexes in QO. In other cases, you have to buy the two tandem breakers and the QOTHT yourself – ThreePhaseEel Oct 8 '19 at 23:01
  • I agree but finding left and right tandems other than this is tough, I have a few in-line style that are easier to even make 2 double pole handle tied possibilities, with side by side tandems , square D only has 1 possible configuration. No twin double pole like other brands have, but I still prefer square D because they are professional and top end residential with the same breaker, have installed thousands. But for home types doubling up may be easier with other brands I agree. – Ed Beal Oct 9 '19 at 2:06
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By permissible I mean: strictly allowed by the manufacturer & therefore to code.

Code has no problem with handle-tying. The issue is whether the manufacturer will offer it and will UL list it. Those two processes do the vetting as to whether it is safe.

(I'm sure you could rig something up but if you want to do it by the book & know that it is safe, that may not cut it.)

Exactly... If the manufacturer doesn't offer it, there's a fair chance it cannot be made safe. They wouldn't put themselves at a market disadvantage if they didn't have to. If they do offer it, shrug, might as well use it.

You can also try a "Classified" breaker, for instance if QO won't offer it, try Siemens QD or Eaton CHQ.

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  • Square d handle ties are not plastic but a metal spindle. Most other handle ties are metal clips. I am sure you can find some but most are metal that lock in place once pressed on. Today it is cheaper to purchase a common trip breaker than a handle tie. – Ed Beal Oct 9 '19 at 2:11
  • I think you misread the second quoted text (or I wrote it unclearly). I was saying that a DIY handle tie probably could not be safe. – StayOnTarget Oct 9 '19 at 12:01
  • As far as the "to code" part goes - I was thinking about the rule that code requires you to follow manufacturer's instructions. – StayOnTarget Oct 9 '19 at 12:02

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