Main/Sub Panel Replacement

[Hamberg]

Best practice question (not sure I want to know the answer )

Need to run (at least) 2 new circuits/subpanels - garage, shed. No open spaces on main service (200A) or subpanel. Picked up a 200A 42 BON QO panel and was going to replace the sub. Now I'm thinking that the new QO should replace the main and the current main moved over to where the sub is now.

Any down-side to using the new one to replace the current sub?

 

[Sparky617]

I'd probably return the panel and just install a couple of dual breakers on either 15 or 20 amp circuits. These allow you to have two circuits in one slot. Replacing a panel is something that would require a permit here and in doing it I'd likely have to upgrade all the circuits for lighting and receptacles to Arc Fault/GFCI breakers at $60 each. It looks like your sub panel has one in the second to the bottom slot on the right. There is no reason you couldn't swap out a couple of the singles for doubles for other circuits. Much easier, cheaper, and less disruptive.

 

[Hamberg]

I'd probably return the panel and just install a couple of dual breakers on either 15 or 20 amp circuits.

Trying to "future-plan". Need a 100A sub in the garage, 30A for new shed & at least 1 2-pole space for a future accessory. Also planning a (whole house) generator mid-year. I believe the main panel (CH32B200J) is 32 space/32 circuits and the (newer) sub (on left - Eaton BR2020l125) is 20 spaces/20 circuits but already has one tandem installed (guessing that would get called on inspection?).

Could get away with cheaters but would prefer to do it right...

 

[Sparky617]

The "cheaters" aren't cheating. They are every bit as code compliant to the full size breakers. I get the future proofing idea, but if you replaced a few of the singles with doubles you'd have plenty of room for the 2 pole breaker for your garage. Changing the panel will not magically supply your house with more total amperage. Here we have main panels outside out house that are part of the meter base. My unused range outlet (we have a gas range), two of my three HVACs, a new EV charging circuit, and my two sub panels breakers are all in this panel. It is now full, if I were to upgrade I'd probably upgrade this panel. I had enough space for my new basement panel and the EV circuit. I'll leave the expense of swapping out that to a future owner should there come some need for more power in the house. The change that could happen would be a requirement to go to electric water heating. I'm not going to go through the expense of running a cable for some future electric water heater on the off-chance that we phase out gas water heating in the next 40 years. Right now I have a gas dryer, range, and water heater. All but the water heater have electric circuits run to support a swap to electric.

 

[Hamberg]

The "cheaters" aren't cheating. They are every bit as code compliant to the full size breakers. I get the future proofing idea, but if you replaced a few of the singles with doubles you'd have plenty of room for the 2 pole breaker for your garage.

Understood, obviously not looking to increase amperage just to make sure I have room for expansion and am code compliant.

Technically, neither panel (by specification) allow tandem breakers (not saying they aren't made, as the sub already has one). Pulled permits for the sub panels, which will be inspected and I'd rather have it done right to start (not that an inspector would check part #'s to specifications but better safe than sorry?)

 

[Sparky617]

An alternative could be to add the third panel and pull enough circuits from the original main to give you room for the breaker for your garage sub panel and your new sub. It would give you plenty of room for expansion without having to relocate a couple of dozen circuits.

 

[Guzzle]

Trying to "future-plan".

A commonly used “investment horizon” is 10 years but almost everyone moves out after 14 years.

Probability of needing to run a cable 100’ long within 10 years is 90% & costs $200. 0.9 x $200 is an expected cost of $180.

Probability of needing a shop reno. within 10 years is 10% & costs $1800. 0.1 x $1800 = $180.

Assign your own probabilities & dollars. In this case it’s a tossup/coin flip between these two options.

 

[Hamberg]

An alternative could be to add the third panel and pull enough circuits from the original main to give you room for the breaker for your garage sub panel and your new sub.

Good call, hadn't thought about that! Only issue is space - in that I don't have any to fit another panel .

Which brings me full circle and I'm leaning towards replacing the sub.

 

[Eddie_T]

Space kinda dictates solutions. A licenced electrician told me my panel might not meet current codes for access. I needed a new panel as in my old one a main breaker contact had failed and burned and pitted one bus. He said pulling the meter for panel replacement would trigger re-inspection and was concerned if grandfathering would apply. He volunteered to remove/replace the panel working hot for $600 (parts & labor) I said go for it.

 

[Guzzle]

For you decision minded lurkers. . .

Assigned benefit of “cable” is 3 “units” with “reno” at 8.

Expected usefulness to you of each is
0.9 x 3 = 1.8
&
0.1 x 8 = .8.

usefulness/cost ratio of each is
1.8/$180 = 1%
vs
0.8/$1800 = 4%.

Do the shop.
Not what you expected, is it?
But if you picked "shop" you could be a rational decision maker. But non rationals could have also chosen this, anyway.

Risk is another angle, demo-ing existing structures.

 

[Eddie_T]

Life is too short for all that!

 

[Hamberg]

Space kinda dictates solutions. A licenced electrician told me my panel might not meet current codes for access.

HOT!?!?! I'll do switches and outlets but a main panel - that takes huge canuggies!

Sooooo, my "space" passed inspection last time around when the sub-panel was added (not my doing) in 2011. Need to confirm but I think we are at NEC2014 in our Township - so there is a possibility something has changed.

Anyone know the section/subsection for enclosure requirements? I have 40"'s across the back wall where the sub is now. In theory, and if allowed, I could move the (current) sub to the left and add the new next to it.

That would also allow me to segregate a bunch of circuits that would not be needed when the generator goes in.

 

[Hamberg]

Think this is the requirement via NEC2017...


EDIT: so the question is; could I move the existing panel over a couple inches and put a new panel in right next to it? (assuming all doors open to at least 90°)

 

[Eddie_T]

HOT!?!?! I'll do switches and outlets but a main panel - that takes huge canuggies!

Not as bad as it sounds, it was only hot for a little while. He wore gloves took the mains and neutral out one at a time and taped them before doing any other work. Then after the new panel was in place he un-taped and placed lines and neutral in the lugs. After that the main breaker was off as he placed individual breakers in.

 

[Guzzle]

Life is too short for all that!

I screwed it up, anyway. Bit off more than I could chew. Just doing a spreadsheet on this took a few tries.

But I can now trade off necessity, cost, benefit & risk and give a number for the best choice. After you plug in & assign
likelihood it is necessary within a few years (10% to 90%),
dollars, (US dollars preferred!)
benefit (1 to 9)
& risk (1 to 9).

Life is too short not to make decisions you can back up. And if I choose to downhill ski in Canada or water ski in FL, the numbers should back me up after I decide. Second opinion!

BTW, working hot or not, only 1800 per year get electrocuted, out of 8000 per day from any cause.
With gloves & arc flash gear & these numbers I'd work hot on res. panels, no calculations req'd.

OK, back to Geeksville for me.

 

[Eddie_T]

We can agree on geeksville.

 

[Guzzle]

You missed your calling as a diplomat.

 

[Hamberg]

(@Eddie_T) Asked over on the Mike Holt's forum and got the nod for the layout below. 85% sure I'm going to replace the main service panel (no! not doing it hot!) with the new QO panel and move the others over. Will give me the chance to upgrade circuits to AFCI/GFCI and segregate circuits when the generator goes in.

 

[Guzzle]

And I assume that they used the NEC's Diversity, Load & Demand factors to make this call.
In a way, the NEC can predict the near future because they have a "memory" that goes back to the Year One & they know what everyone is doing and has done.

Diversity factor
the sum of the individual maximum demands of the various subdivisions of a system divided by
the maximum demand of the whole system.
Diversity is usually more than one.

With our breakers, our household usage has not proved out this factor, with 100A or our 200A service. I think the previous owners of our place were oversold.

 

[Hamberg]

And I assume that they used the NEC's Diversity, Load & Demand factors to make this call...

Not at all, 110.26(A) is pretty clear on the requirements