Square D tandems and double tap

Are tandems allowed in this panel? It says 40 space, and all were filled. There were 6 tandem/piggybacks. Also, is double tapping with different gauged wires on Square D saddle clamp permissible (last pic)? In theory with a saddle type clamp you wouldn’t think so, but these were secured well and the smaller wire was not loose at all.


Pic 1 says no… but can’t see it all.

No, and should be stated on the breaker.

Theory, again No. May be tight today, but what about next month or next year or 5 years down the road? Manufacture says No. Period. Let the Sparky’s hash it out if they don’t like it.

This is, typically, what the diagram looks like when tandems are allowed:

And, the bottom 10 spaces:

Those are easy ones;-) The reason I asked is because of this: http://structuretech1.com/2010/01/how-to-correct-double-tapped-circuit-breakers/
Scroll down to the bottom Square D with the lines in it. Apparently blanks without lines do not allow tandems? These all had lines…all 40 spaces. But then I refer back to the 40 space? if this were the case wouldn’t 80 be allowed- lol?

They all had “lines” in the middle…see post #4

Obviously I cant see that, but the SD breakers I have seen (or remember) with the saddle clamps say #14 - 8 gauge or something to that effect. They don’t really state that they have to be same size wire.

You mean this?:

If so, the writing says the yellow are okay for tandems…

Yes, that’s what I’m getting at. The boxes with lines in them, just like what I have pictured, are acceptable for tandems. The highlighted/yellow areas were created by the author to show better (the actual label isn’t yellow;-))

In other words, the little lines are throwing me off and/or making me question the acceptability.

That panel does not allow tandems. If the label or model number said 3040 it would allow tandems. This is a straight 40 pole panel.


I agree. I’m surprised that the tandem CB’s even fit unless there was a modification made to either the panel or the CB’s.

I would add that these are Homeline CB’s which only allow one conductor. Sq D type QO allow two conductors but the sizes are limited to the combinations that are depicted on the side of the breaker.

What? They all had the saddle type clamps for 2 conductors. So you’re saying that you can’t have 2 conductors if they have the saddle type clamp?

The sticker on those breakers say 2 CU conductors allowed, however they don’t look like OEM breakers, and that panel is a 40 circuit - 40 space panel…no tandems allowed.

No, I was referencing the Homeline tandems which I believe are listed for only one conductor.

The tandem breakers look like they have improperly configured multi-wire branch circuits on them too, but can’t fully confirm from the photos. If the red/black conductors have a shared ground the two on the right are definitely improperly configured (both conductors on the same phase can overload the shared grounded conductor) and the one on the left may be too. Of course if they are MWBCs (I would bet that they are) they are missing handle ties, but that’s trivial compared to the wiring issue.

Looks like they outgrew the panel.