Sub panel or upgrade panel

[JBeaulieu]

Looking for some guidance:

2000 SF home currently served by a 100A main panel (QO8W 20M100-5) that is pretty well full from what i can tell
(2) 30A circuits one for a dryer and one for a/c
(1) 20A circuit
(13) 15A circuits
(2) Tandem 15A circuits for a total of (4) 15A

Purchased a dual fuel range 2nd hand not realizing it would need 220V. Requires 20A.

I am sure most will recommend having the panel upgraded to 200A, just not sure I can swing that. Is a sub panel an option? It seems like it would be pushing the limit to add, but if it is an option, it would seem to me that a 50A sub panel would make sense that would protect the dryer and the newly added range. In that case do they swap the 30A breaker for a 50A, and run the sub off of that?

Would like to have some sense when reviewing with a contractor so I am not misguided. Thanks.

 

[Reach4]

You could probably turn the existing panel into a subpanel for the new 200 amp breaker panel. That would minimize wiring to the existing circuits. It is possible that you will need bigger feed wires coming in too. Ask your power company.

I am not an electrician.

 

[Sponsor]

 

[Stuff]

Check the panel label to see if it really is allowed to have tandems. If it is then replace some singles with tandems to make space. Sometimes you need to add a ground bar as well.

Reach's idea of a new service with 200 main would work. If you go to the expense of a new service most electricians would rather swap out your panel with a 40 space one.

Your panel idea is fine. Sweet spot price wise is to use a 60amp double pole breaker to feed a subpanel using 6/3 cable. Use 100 to 125 amp MLO panel or whatever is on sale. If main breaker can be 100a as it is considered a disconnect. Usually only single phase/120v loads are moved over and the 240v remain in the primary panel.

Last option: Change your dryer to gas.

I'm an engineer. That means most tradesmen stay clear because I come up with unreasonable requests.

 

[Jadnashua]

Any idea what your typical peak load on the panel is? It is very normal to have more branch circuits total capacity than the main, but the last thing you want is to have your actual load get to the point that you trip your main breaker. A subpanel doesn't make more capacity available, but it does give you more room to expand, and that can be problematic if taken too far. You normally don't want to exceed 80% of the main's capacity for very long.

Depending on what the incoming power drop's wire size is, you might be able to upgrade the panel to a larger one fairly easily.

 

[Cacher_Chick]

Given more energy efficient appliances and CFL/LED lighting, the average power consumption in most homes has gone down.
100A service adequate for the average single family home unless it is heated with resistance heat and/or has a pool/whirlpool heaters etc.

If I were you, I would simply upgrade to a QO 100A panel with 32 spaces, enabling you to keep using your existing breakers and save a lot of money by not having to invest in a larger service.

 

[Jadnashua]

FWIW, in the next few years, a lot of people are going to be looking at an EV (electric vehicle) and you'll want at least a 40A extra capacity to have a chance of recharging it overnight once larger batteries become the norm. The guy that installed my EVSE said in CT, all new homes must be wired for one (similar to what you might find for an electric dryer) so that it can be installed easily. Personally, would have liked to put in a larger one, but I could not safely do it on my 100A service. Being in a condo, bringing in a larger line would be very expensive and inconvenient since it runs through the basements of the townhouses next to me (I'd need to go though about 5 units to get to mine), and the subsequent lining up owners and getting permission, then fixing their ceilings...a non-starter.

Unlike say water and gas, most places don't charge extra to have a larger service for electricity. You never know when it might be useful.