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So I know this question has been asked before, even by me, but I am at the point where I can be more specific, using information provided to me in another posts and specific info on my loads.

I am adding a sub panel to support a kitchen renovation. The old kitchen had minimal electrical components so much more is being added.

Existing panel is Square D, 200amp, 48 space with 4 empty spaces.

The new panel will be about 10 feet away. New panel will support:

  • 15 amp oven exhaust fan circuit x 1
  • 20 amp outlet circuit x 9
  • 20 amp microwave circuit x 1
  • Pot light circuit with 13 Lights: 140 mA each and one Smoke Detector: 687 mA
  • Pot light circuit with 9 lights: 140 mA each and 3 bedroom 15 amp outlets
  • Dishwasher (12 amps) x 1
  • Fridge (5 amps) x 1
  • Freezer (5 amps) x 1
  • Possible Future AC - Estimate a 3 Ton, estimate 15 amp running and 75 amp startup

Total spaces: 18 (if i include the AC on the sub panel)

The oven/range will remain on the existing panel

Equipment I’m considering:

  • Breaker Panel: Eaton CBRPL130 - 125Amp, 30 spaces (I didn’t go with a 200amp panel because of the cost of the feeder breaker)

  • Feeder Breaker: QO2125 - Square D 125 Amp Double Pole

  • Neutral Lug: LK125AN 14 to 2/0 AWG Copper/Aluminum

  • Ground Lug: LK70AN

  • 1/0-1/0-1/0-2 Al SER from existing panel to the new panel

So my questions are:

  • Will the 125Amp panel suffice?
  • Is the equipment I’m considering adequate
  • should i be working towards trying to ensure there is space on the existing panel for the AC rather than adding it to the sub panel?

Thanks is advance!

Some additional info based on comments:

  • Yes, this is in Canada (Ontario)
  • I’ve got two long countertops and an Island, so this takes up 7 20 amp circuits. Yup, 1 additional circuit for a nearby bathroom and one for in the basement below the kitchen.
  • Square feet being serviced is about 350
  • Yup, its a big exhaust fan (46” typhoon) It is over a 6 burner gas range with a griddle.
  • As suggested, I’ll look into the 200amp panel but still use the 125Amp breaker. Like I said in a comment below, I’m sick of looking at the different panels. Function/cost/availability options times makers feels like overkill!
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  • 20 amp outlet circuit x 9 Is that just for the kitchen? Because you can have multiple receptacles on a single circuit. 2 circuits are required for kitchens, and 3 or 4 is better. But 9 is overkill unless some of those are for other rooms.
    – manassehkatz-Moving 2 Codidact
    Sep 13, 2021 at 15:41
  • AIUI, you don't need a 200A breaker in the main panel just because you've got a 200A sub feeding from it. You can, if you desire, have a 200A main breaker in the sub panel with a 125A breaker in the main panel. Of course, if you ever try to draw 200A from the sub, the breaker in the main will trip, but if you're reaching that much draw, it's probably time to upgrade the supply side breaker anyway. You can run wire rated for 200A between the panels in preparation for a future update if you desire. (Not an electrician, get confirmation before acting.)
    – FreeMan
    Sep 13, 2021 at 15:58
  • Do not forget the garbage disposal if allowed in your area. Several of those breakers will have to be either AFCI or GFCI type.
    – Gil
    Sep 13, 2021 at 17:04
  • "(I didn’t go with a 200amp panel because of the cost of the feeder breaker)" the feeder breaker does not need to match the panel rating. It only need be <= panel rating (60A feed breaker-> 200A panel is perfectly OK, and will save you some coin on the breaker lol).
    – Harper - Reinstate Monica
    Sep 13, 2021 at 18:36
  • How many square feet is this subpanel serving for lights/receptacles? Also, what sort of a brute of an exhaust hood fan are you putting in, and I take it those 20A outlet circuits are serving the kitchen countertops?
    – ThreePhaseEel
    Sep 13, 2021 at 23:42

1 Answer 1

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Will the 125Amp panel suffice?

(I didn’t go with a 200amp panel because of the cost of the feeder breaker)

The subpanel rating is a redline, a maximum - like your car's 112 mph rated tires. There is no need to match the subpanel redline rating to the supply breaker.

So feel free to use a 225A-bussed subpanel downline of a 125A, 100A, 90A or even 60A breaker. It's all good.

If anything, going with a 200A class subpanel will simplify service upgrades - the next step up is "Class 320" 400A service, and that is configured as feeding two 200A panels. (since 400A panels are cost prohibitive).

Also, if the subpanel is in the same building, it does not need a main breaker at all, and a main-lug panel will suffice. However, go with whatever works out cheapest - often main-breaker panels are sold in combo-packs with some breakers!

Is the equipment I’m considering adequate

Your intuition is telling you to go for a 40-space panel, and I'll certainly encourage that! "Get a BIG panel" is our favorite advice around here.

But it looks like your plan is well-researched overall, and I have nothing to add.

should i be working towards trying to ensure there is space on the existing panel for the AC rather than adding it to the sub panel?

Well, it's always nice to put the big loads in the main panel, as that means a smaller subpanel feed wire will suffice. However, if your plan is a 125A feeder, you'll have great gobs of room.

The trick is not to be confused by amps, which get a bit weird going from 120V to 240V. With this many circuits in the panel, think VA - which is volts x amps. (or basically watts, with an asterisk). A 125A feed has 240V x 125A = 30,000 VA.

A notable point is that startup surges don't count. The system is already factored for those. So...

  • 200 VA or so -- 15 amp oven exhaust fan circuit x 1
  • 180 VA per receptacle -- 20 amp outlet circuit x 9
  • 1800 VA, conservatively -- 20 amp microwave circuit x 1
  • 370 VA -- 22 pot lights: 140 mA each
  • 10 VA ** more realistically -- one Smoke Detector: 687 mA
  • 540 VA -- 3 bedroom 15 amp outlets
  • 1500 VA -- Dishwasher (12 amps) x 1
  • 100 VA * -- Fridge (5 amps) x 1
  • 100 VA * -- Freezer (5 amps) x 1
  • 4500 VA (3600 VA x 125%) -- Possible Future AC - Estimate a 3 Ton, estimate 15 amp running and 75 amp startup

I count 9120 VA + 180 VA per receptacle, so we're miles and miles away from 30,000 VA. Heck, you could probably support a 12,000 VA electric vehicle charge port on this, and still not be near 30,000 VA.

By the way, there's an alternate computation method: you take the big stuff, plus 1500 VA for each kitchen, garage, bathroom and laundry circuit, plus 3 VA per square foot of domicile. But still, we're miles away.

* Modern refrigerators and freezers draw less than 1 amp when running. They average about 40 VA, or about 1 KWH per day.

** Smoke detectors don't take 80 watts - they'd be hot to the touch if they did!

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  • Thank you for all the details and feed back. It is much appreciated. I’ll look into the 200amp panels as you and others have suggested. (Honestly though, I’m sick of looking at panels! It’s like cellphone plans, there are so many options it’s crazy to determine best functionality/cost/size).
    – Oldoldhouseguy
    Sep 14, 2021 at 17:28
  • @Oldoldhouseguy Actually a lot easier than cell phone plans. With rare exceptions (panels that are either way too small or that years later turn out to be dangerous), once you buy a panel and install it, you are done. With a cell phone plan, at every month/year/2-year renewal you (a) have a possibility that the carrier may change the plan with little notice and/or you may decide that it is worth switching (and all the related research needs to be done all over again because all carriers change plans frequently). Plus no hidden gimmicks - WYSIWYG.
    – manassehkatz-Moving 2 Codidact
    Sep 14, 2021 at 18:08
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    @Oldold Easy! Start with 1) the spaces you want, then look at 2) the brand you want, either to match your panel, or based on features (generator interlock availability. 1-wire AFCI support: GE. Exotic breaker availability: BR. 200A breaker availability: Square D HOM. Etc.) Then 3) decide if you want Plug-On Neutral (only relevant to GFCI/AFCI). And 4) if you want a main breaker. And 5) if you need outdoor-rated. At that point you're down to 2-3 options even in the catalog, and now it's a "can't find it in stock anywhere" problem lol. I'm not helping, am I? :)
    – Harper - Reinstate Monica
    Sep 14, 2021 at 18:51
  • @Harper-ReinstateMonica Thanks...um sort of :) I had not thought of the generator interlock. Hmm, I’ll have to check that out. I’m going with a PON Panel. GFCI will be taken care of by the outlets. I will need at least one AFCI circuit. Other than the interlock, does the Eaton CBRPM240 BRPON MAIN LC 200A take care of what i need or are there any lacking capabilities that this may have?
    – Oldoldhouseguy
    Sep 14, 2021 at 21:32

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