Here's a slick Canadian subpanel with a "generator interlock". It is a normal 2-pole panel, just like common USA panels, and it's Square D QO, which is common as dirt in the USA. However for the generator interlock, it uses 3-pole breakers (this series of panel is also made in a 3-phase version, so the 3-pole breakers are also common). The third pole switches neutral.

We often have applications here in the US where someone needs a generator interlock/transfer switch, and there are loads of things like this on the US market, but they are only 2-pole (no neutral). That won't cut it, because they are coming off an inlet from a portable generator, and most portable generators have neutral-ground bonds, which means neutral must be switched. (the consumer can't be counted on to install and remove the N-G bond every time he uses the generator).

This thing is both CSA and UL listed (CSA is a US Nationally Recognized Testing Lab) and actually made in the USA. So could I just pop across the Friendship Bridge, buy one in Home Depot.CA, and use it in Virginia? Or is that statutorially disallowed, and if so, by which Code cite?

  • The correct question to ask is: What does MY LOCAL CODE require/permit? Even "Virginia" is not specific enough since your local jurisdiction may have requirements different from other parts of the state. The fact that it's CSA is, in my opinion, irrelevant. It is, UL listed but that doesn't make it compliant with your local codes. For that, you'll need to consult the codes themselves and ensure that you are compliant with the application. – jwh20 May 27 '19 at 16:48
  • @jwh20 this is under the purview of 110.3 re: listing and labeling -- inspectors generally defer to the UL listing on a listed/labeled product such as a panelboard, as trying to field verify compliance to UL 50 practically requires UL to bring their truck o' gear out... – ThreePhaseEel May 27 '19 at 16:53
  • Can you get me the UL file number off of one? The drawing Schneider Canada provides only lists the CSA file number, and I don't think it's cCSAus, although I can see if I can access their database... – ThreePhaseEel May 27 '19 at 16:54
  • Yeah, I can't find it either nor do I see the C/US device on the CSA mark. Photos aren't focusing on that. I'd love to go check one out, but I don't want to get 50 lashes with a wet noodle for reentering the US without proper papers... – Harper - Reinstate Monica May 27 '19 at 16:58
  • @ThreePhaseEel My point was that UL listing in and of itself is not the final determining factor as to whether or not a specific piece of equipment is legal in a particular use or locality. There are plenty of UL listed components that, when used or installed incorrectly, are dangerous and illegal. – jwh20 May 27 '19 at 17:16

In your specific case, no, because the labeling is wrong (or you just can't get what you want)

Looking at the photos on HD.ca, it is clear enough that the panel is not labeled for service in the US, as it would either need a cCSAus mark, or a UL mark alongside the CSA mark, in order to be usable in the US as well as Canada.

Generally speaking? I'm not sure

I am not certain if one could make a binational loadcenter assembly that was listed and labeled cULus or cCSAus; it depends on how harmonized UL 67 (the UL standard for panelboards) is with its Canadian counterpart.

As to accomplishing the end goal here...(but you just might be able to get what you need)

There is good news and bad news here. The good news is that it's possible to do this while staying within the QO product line as a whole; the bad news is that you need to use unit mount breakers (and a few jumper wires) to do this because QO loadcenter interiors do not support retaining backfed breakers in arbitrary positions.

You'll need:

  • Two QOU3xx breakers (you can go up to 70A for the generator and up to 125A for the utility, wire bending space permitting)
  • A QOU1xx breaker to serve as a "dummy" pole (if the utility breaker is 70A or less)
  • A QO3HT handle tie (if the QOU1xx is necessary)
  • A QO2DTILA interlock kit
  • QOUMFS1 threaded mounting feet, two per breaker pole
  • 8-32x3/8" mounting screws, two per breaker pole
  • Insulated three-port mechanical splice connectors (three) and suitably sized jumper wires (six) to connect the load-side hots and neutrals together
  • And a box to wrap this all up in (the box and trim from a QO816L100xx loadcenter should do the trick quite beautifully, just yank out the loadcenter interior, take care of the twistouts, drill some holes in the trim for the 8-32 breaker mounting screws, and fit a ground bar to the box)

What you want to do here is flush mount the breakers to the enclosure cover (trim) in a 3-1-3 configuration (or 3-3 with the utility on the left if using a >60A breaker on the utility side), then mount the QO2DTILA to the left side of the rightmost breaker. Finally, if the dummy breaker is being used, it needs to be handle-tied to the leftmost breaker in this configuration.

Wiring-wise, one side of one 3-pole breaker goes to the utility (hots + neutral), while that side of the other 3-pole breaker goes to the generator. The opposite side of the 3-pole breakers gets wired in parallel using suitably sized jumper wires and splice connectors, and then that can get wired onward to another enclosure (or a loadcenter interior in that enclosure if you're doing more extensive enclosure modifications) to distribute standby power to wherever it needs to go.

As to the 1-pole breaker, if present? It simply is left unwired; its sole purpose in life is to serve as a mechanical adapter between the handle-tie going onward to the left-hand 3-pole breaker and the QO2DTILA interlock as the interlock may slide under a handle-tie space that doesn't have a handle behind it.

  • Note that it might be possible to hack a setup together that achieves what you want here, but it's going to be a terrible hack due to the way the QO interlock kit and backfeed retainers work (spoiler: retaining backfed breakers is not the QO's strong suit...) – ThreePhaseEel May 30 '19 at 0:40

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