I am looking to upgrade my outdoor main panel to a Square D QO panel. However, this outdoor 200A load center feeds my indoor 200A load center, and it does so not by using any of the breaker spaces but instead the bolt on piece at the bottom.

What is this called, and are they made for Square D QO panels such that I could upgrade it?

The part I'm asking about is in the dashed red rectangle. It passes the full current on the bus bar to the indoor panel.

Outdoor Load Center


There seems to be some questions about the neutral/ground bonding in this main panel, it is indeed bonded behind the main breaker in this panel. The Meter neutral comes in on the left, the sub panel is getting its neutral (insulated white) and ground (twisted aluminum) bonded on the right. This all checks out to me, so perhaps this diagram helps clear the situation up?

Ground Wiring

  • I don't think that panel is right- there's no connection between the two bus bars. The neutral from the meter comes in and is attached to the left side, whereas the neutral for the house is fed off the right. I see a ground wire on the left to the box, but not that appears to be entering the ground.
    – J.Hirsch
    Apr 13, 2020 at 17:40
  • @J.Hirsch I agree with you (see my comment in the answer part). Unless there is a conductor hidden behind the plastic part that goes behind the breaker, this looks like all the neutral currents are going thru the ground connections. Not good! Apr 13, 2020 at 21:28
  • @GeorgeAnderson There is indeed a conductor behind the black plastic behind the main panel breaker, between neutral and ground. Does that address the issue?
    – Ehryk
    Apr 14, 2020 at 0:46
  • @Ehryk ...Maybe. Normally, what I'd expect to see (and I am NOT a Master electrician or familiar with your local codes) is that all those neutrals are tied together, all the ground are tied together, the box is grounded at the ground lug- and most importantly the strap (that goes between the two bus bars) are intact. For a 2nd panel however that strap has to be broken (which would be your main panel) because that counts as a sub panel. So... I'm not really sure.
    – J.Hirsch
    Apr 14, 2020 at 19:31
  • 1
    @J.Hirsch Seem my 2nd picture in my latest edit. This is my main panel, so the strap is present. On the panel indoors, as a sub panel, it has a separate Ground and Neutral coming into this panel. This meets your expectations then, right?
    – Ehryk
    Apr 15, 2020 at 4:35

1 Answer 1


This is call a FEED THROUGH LUG and it's used for exactly what you have. Feeding from one panel to the next.

Yes, they seem to be available for SOME Square D QO panels but you'll need to check by the model number.

  • I would also suggest comparing the price of the feed through lug kit to that of a 200A breaker, you could then use the breaker to feed the next panel. Not required, but a nice convenience (can de-energeize downstream panel by shutting off breaker, but retain power to main panel). If it's only marginally more expensive, that may be a good option and give you more panel choices as well. Apr 13, 2020 at 17:04
  • Good point. I'd have assumed that one of these feed through lug kits would be less expensive than a 200A breaker but it appears that is not the case. At least not for feed through lugs that are not pre-installed.
    – jwh20
    Apr 13, 2020 at 17:12
  • 1
    @jwh20 What I'm now noticing is that the lugs are not 'bolt on' to any regular panel interiors, they are their own separate interior. So to get Feed Though Lugs on a QO panel, I would have to order the specific panel with the FTLs, not a panel and a separate FTL kit to bolt in. I guess that answers my question then - you don't buy the lugs to retrofit a panel, you buy a panel with them. I think I'll be going the 200A breaker route with a QO2200 breaker feeding the sub panel, so I can have more panel options.
    – Ehryk
    Apr 15, 2020 at 4:43
  • 1
    @Ehryk QO is a premium (commercial/light-industrial-grade) product line that commands a premium price (if you put "Square-D" and "Cheap" together, you get Homeline). Anyway, given that you have a panel inside, 26 spaces (after you count the QO2200 out) isn't too bad for an outside panel Apr 16, 2020 at 3:04
  • 1
    @Ehryk -- yeah, given that you want the top hinged box, you're best off with what you picked Apr 16, 2020 at 3:37

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