my 100-Amp panel is full, new panel or add subpanel?

[bingo]

The main panel for my 1600 sq ft. house is a 100-Amp Challenger SB10 12-space 20 circuit. The breakers are a mix of Challenger, Cutler-Hammer and Eaton BR type. The bedroom receptacles are on AFCI breakers. There is an inspection sticker on the box dated 2005, which was the time of a remodel and I think that was when the arc-faults were put. The service entrance wires are two AWG #3 copper.

I am planning to add an oven that requires a 30-amp circuit, so I'll need to add a 30-amp 2-pole breaker. All of the spaces that can take a double/twin breaker have one already - there's just no way around it, the panel is full! I have done a rough amp load calculation with the new oven and it all comes out to about 103 amps. I am deciding between replacing the 100-Amp panel with a bigger capacity panel (125?) or adding a new small sub-panel.

I think the previous owner upgraded the service wires to the #3 AWG, but left the panel at 100 Amps as that was all they needed. Am I right in thinking that two wires of #3 Copper can carry more than the 100-amps that the current panel is rated for? Is it more like a 200-amp service? The glass meter is owned by the power company, and it seems to be newer (has an LCD display). How do I evaluate it and the meter socket for the amount of service it is rated for?

I'm in Oregon and we follow the 2014 NEC. If I replace the panel with a new 125-amp or 200-amp panel what is the expectation for whether the inspector will require that I use AFCI breakers for all the additional areas besides the bedroom outlets? Besides the oven, I am not adding any other branch circuits or devices.

If I decide to go the route of a subpanel what size would you suggest? The house does not have central A/C so that might be something added in the future but otherwise I don't have any plans to add more circuits (kitchen and baths have been remodeled). I have been hearing some concerns about Challenger panels, I don't see any scorch marks or anything that would make me think that something is overheating. Any thoughts on keeping a Challenger main panel?

So my questions:
1. Given my two #3 copper service wires...what do I assume the service amperage to be?
2. Would I need to upgrade the breakers to AFCI if I replace the panel with a larger panel?
3. Is a Challenger panel a hazard, and/or should I just add a subpanel for the 30A oven breaker?

thanks for your assistance
Steve

 

[Stuff]

#3 gauge copper is good for 110 amps as a service, 100 amp if not handling the entire residence.
Usually a panel upgrade does not force going to AFCI. Up to your local jurisdiction as there are a few that do want it.
Your Challenger panel is just old and small. It was the stab-lock version that had the big problems, not your type. Pull the breakers one at a time and look at the bus stabs.

Sometimes you can find a couple of circuits and merge them to free up a couple of spaces.
Adding a sub works but a new panel would be ideal.

 

[Sponsor]

 

[bingo]

Thanks Stuff.

#3 gauge copper is good for 110 amps as a service, 100 amp if not handling the entire residence.

So since I have two #3 copper wires, I would have 200-Amp service but the 100-amp main breaker and panel keep me at 100 until it's replaced?

While I only need just over 100 amps, is there any reason (besides material cost) to not put in a 200A panel? Since 200 are so common, it seems that the big box stores have Eaton BR 200-A panels that come with a main and some breakers included for about $100, which isn't more than the 125-A panels. If I have the physical space, go to 200A?

 

[Reach4]

So since there are two #3 copper wires, I have 200-Amp service but the 100-amp main breaker and panel keep me at 100 until they are replaced?

No, it does not work that way.

A 100 amp panel lets you power up to 200 amps of 120 volt loads. That is called 100 amp service.

 

[Stuff]

To go to higher amperage you need to upgrade the meter box and the feeds to and from it. Sometimes the power company needs to upgrade its wires as well - especially if underground.
If you look at your 100amp main breaker you will see that it consists of two halves (poles) and both hot wires connect to it. The nomenclature is to call it 100 amp if you have one, two, or even three poles. 200 amp service means 200 amps on each pole/wire.

 

[Jadnashua]

With the addition of that new stove and potentially central air, it makes sense to go to a newer, larger panel. Note, if you bought a 200A panel, but put a 100A main breaker in it, you wouldn't have to change the meter and potentially the feed line from the main line. Want to switch to a 200A panel, change that wiring later and swap back in that 200A breaker. In the meantime, you'll have a larger panel for your new circuit(s).

 

[bingo]

Thanks for the replies.

Just looking at the wires from the meter box to the house and if there was no main breaker panel installed at all - how does somebody figure out what service they have?

In my case I have two #3 AWG copper (stranded) in conduit (above ground) in Oregon's mild climate. The wire is marked: "600 Volts VW1 ESSEX 3-AWG Type THHN or THWN or MTW E53446-K"

The meter is shown below

 

[dslywalker]

Be better to take a pic of the breaker box with the cover off it. Be able to tell more about whats going on in there..You have some gas appliances?
Mike

 

[bingo]

...You have some gas appliances?
Mike

Gas appliances = yes:
water heater, furnace, the new oven is a dual fuel range (gas burners, electric oven)

 

[Jadnashua]

FWIW, the power company sometimes gets by with using smaller wires than you can inside. I'd give them a call and ask what you have, and what it would cost (if anything) to upgrade to say a 200A service.

 

[dslywalker]

100 amp services were the norm when most of the heavy stuff was gas..Range and water heater and furnace would have close to 80 amps if they were electric.. I'm with the rest of them check on upgrading to a 200 amp.. Especially if you plan on staying there awhile.. Don't know what your hobbies are or what you do. Least you'd have some room for future add-ons

 

[bingo]

Thanks all. I found the chart of allowable ampacities of conductors. It's no longer a part of the 2014 NEC as the rule became a calculation, but it is a good reference http://www.encorewire.com/wp-content/uploads/wire_size_table.htm60A

In my case I'm going to put in a 125A panel as a sub and put a 60A breaker in the main for it.