Less ugly transfer switch?

[mciholas]

For my parents house, there is a main and a backup panel. I'd like to have a double throw manual transfer switch to change the backup panel from being powered by the inverter load connection to the grid directly in case of inverter failure or service. Max load would be 80 amps, 2 pole (split phase).

This seems to be the best I can find:

https://www.eaton.com/us/en-us/skuPage.DT223URH-N.html

It is a bit ugly and big. It will require surface mounting on a wall where the breaker panels are already flush mount.

I prefer not to do a main breaker and feeder breaker interlock slide due to inspection issues and the fact the sub panel has no main breaker installed. Is that code compliant and will it pass inspection if I did that?

I see nice looking rotary cam switches, but they seem to be European market and not UL listed.



It has to pass inspection, so UL listed/certified.

Any suggestions? It is just a DPDT switch, don't need fusing, how hard can this be?

Mike C.

 

[hwy17]

No they don't get much prettier than that.

You can probably get a main breaker kit for your subpanel.

 

[Hedges]

I prefer not to do a main breaker and feeder breaker interlock slide due to inspection issues and the fact the sub panel has no main breaker installed. Is that code compliant and will it pass inspection if I did that?

I did this, and the inspector questioned it because interlock is removed with bezel, and I was backfeeding a panel prior to utility moving overhead drop to where it would feed this main breaker, but he let it be.

Cost for utility transformer installation?

slightly OT. There was a review of the Emporia Energy Monitor on Amazon, which mentioned that the house meter records more kwh usage when the pull is unbalanced between L1/L2. Is this a possibility ?

diysolarforum.com

It is from Square-D and UL listed. It tends to enforce a delay as you switch off main, slide interlock, switch on backfed breaker. You would of course have to buy a bolt-on main breaker as well, assuming your panel is convertible main lugs.


Elsewhere I also use a square-D generator panel that came with two interlocked branch breakers pre-installed. Those, when bezel is removed it is still interlocked. It also allows near instant snapping between two (out of phase) sources.

 

[ricardocello]

I was so put off about the big ugly expensive transfer switches that I decided to design two new critical load Square-D subpanels.
The “generator” interlock kits for them are up to code here, so that seemed like a cleaner solution.

I ran 50A interlocked breakers to 50A CS6364 locking connector inlets. Perfectly allowed by code, and no one needs to know what I plug in there.

 

[Mattb4]

You might could build a box for it to be hidden in. Like a book shelf cabinet or fake wall safe looking thing. Or maybe just dress it up with some clever painting.

 

[timselectric]

I'm for the interlock option, also.
It's the simplest and least expensive.
As long as the panel can be converted to main breaker.

 

[mciholas]

No they don't get much prettier than that.

Sad.

You can probably get a main breaker kit for your subpanel.

Yes, I can do that.

The issue is that the sub panel is 24 positions and I need all of them, so using two for an inverter back feed breaker hurts a bit. I could use the tandem (2 circuit) breakers, but the existing panel isn't rated for those, so would need to be changed anyway. Or I need to cut the backup panel to 22 circuits.

I could install a new sub panel with more spots and a main breaker, which is more work but probably cheaper, and use the slide interlock which is cleaner and doesn't require installed the separate transfer switch.

I see you can buy UL listed slide interlocks, so perhaps that is the way to go.

Mike C.

 

[Hedges]

I could use the tandem (2 circuit) breakers, but the existing panel isn't rated for those, so would need to be changed anyway.

Rated, Schmated.

Some panels/breakers are "circuit limiting", have clip rails with or without slots so tandem breakers with hooks fit only in some places.

But there are tandem breakers that aren't "circuit limiting", clip on to any panel even without slots.

Install a larger ground bar if required to provide enough connection points. Probably neutral bar is already large enough for N + G, so plenty if N only.

Your existing non-tandem 20A or 30A breaker probably already accept 2 wires per terminal, so you can double up a couple displaced circuits on other circuits. Either permanently, or to avoid using tandem breakers until official work is complete and approved.

 

[mciholas]

I did find this:

https://www.se.com/us/en/product/download-pdf/QOGP3P6036P?filename=Schneider+Electric_QO-Generator-Panels_QOGP3P6036P.pdf

It is called a "generator panel". It has two 3 pole breakers interlocked and then 18 spaces for QO breakers (up to 36 circuits with tandem breakers). I need to power 22 to 24 circuits, so I would need a few tandem breakers to make that work in the 18 spaces.

Not frightfully expensive, about $260 with two 60 amp "main" breakers, which is what I need. The tandems do cost a bit more, though. This would replace my existing backup panel.

The "main" breakers are 3 pole because they can isolate the neutral (it isn't a 3 phase panel). For the designs I am looking at, neutrals are all tied together, so the 3rd pole is redundant but harmless to have.

The interlock is rotary, both breakers have to be off and then rotate it to have the notch facing the breaker you want on. The interlock may also come off with the cover (like the other slide interlocks), but hard to tell if that's true or not. If it stayed with the breakers, that would be a plus.

This seems moderately elegant and compact for what it does. Not sure I want to rip out the backup panel to put it in, but I am considering that. A slight annoyance is that it is 2 inches shorter than my backup panel, which will leave a drywall repair. I also think the wiring will be tight to have two 60 amp feeds and 24 circuits in this small box, but that's a one time hassle.

Mike C.

 

[Hedges]

They have several sizes of standard (non-generator) panels, maybe one fits your hole.
An interlock can be added (if not available for the model panel you already have.)

There are interlocks that slide to allow main breaker or a branch breaker to backfeed, and there are interlocks between two branch breakers.

I got a somewhat larger panel in the small main breaker format. There are also several sizes with larger breaker format.

 

[Hedges]

Oh, consider just combining two circuits onto a standard breaker instead of using tandem.
Fit everything inside existing panel, just making room for interlocked breaker.
No need to rip out panel. Minimum effort, Path of least resistance.

 

[wpns]

As long as the panel can be converted to main breaker.

Don't even need to have a main breaker, InterLocKit.com has ways to interlock normal breakers as well.

 

[timselectric]

Don't even need to have a main breaker, InterLocKit.com has ways to interlock normal breakers as well.

Yes, but the OP is already limited on breaker space.

 

[ricardocello]

InterLocKit.com has ways to interlock normal breakers as well

Hey, didn’t know about those guys! thanks

 

[mciholas]

Don't even need to have a main breaker, InterLocKit.com has ways to interlock normal breakers as well.

The correct URL is:

Interlock Kit & Accessories For Your Home | Generator Interlock Kit

Our Interlock Kits act like manual transfer switches for electrical panels providing safe, easy connections between homes & portable generators.

interlockkit.com

(the other is a cloud services company, one "k" only)

$150 for a metal slide. Hmm...

Square D makes an official UL Listed one that you can buy for under $70:

QOCRBGK1C - Load center accessory, QO, interlock kit, generator circuit breaker, low amp, outdoor, clam packaging | Schneider Electric USA

Schneider Electric USA. QOCRBGK1C - Load center accessory, QO, interlock kit, generator circuit breaker, low amp, outdoor, clam packaging.

www.se.com

Mike C.

 

[JWLV]

How about something like this? I kid.

 

[Hedges]

$150 for a metal slide. Hmm...

Square D makes an official UL Listed one that you can buy for under $70:

Yeah, for a while I thought $50 or so was excessive for a stupid piece of metal. That is what I was paying for an entire breaker panel with copper busbar. It is worth $5 tops, wouldn't mind paying $15.

But compared to the alternative, it was competitive. And UL listed (at least the one from Square D.)
I have a couple in use and more stashed away in my drawer.

I have one of the rocker sort for side by side branch breakers, came pre-attached to a 100A generator panel.
I want to get some of those for retrofit but have only seen aftermarket.
My application would be to use together with the sliding one: Main interlocks to generator backfeed from inverter output interlocks to inverter input.