Electrical service question - old house, new addition - expert advice needed

Hi,
I have an electrical service question and have gotten 2 or 3 different answers. You can probably tell, but I am a novice. Maybe someone here can help.
I have a 1000 sq ft brick/slab foundation house in the U.S. (electric water heater, electric dryer, electric stove, no central air) that is 40 years old (grey cloth-covered copper wire).
Outside the house is a meter and separate breaker box with a two 30amp and two 20 amp breakers. Two circuits from this outside box run along the outside of the house to an electric dryer and private sewer system.
Inside the house directly through the brick wall is an inside main with no main breaker visible. In the inside box (12 slot), there are 8 breakers: One 100 amp double throw (stove), one 60 amp double throw (electric water heater - which will be probably be replaced with a LP unit during the remodel), one 30 amp double throw (?), and a mixture of 20 amp single and double throws. One slot is empty.
I am adding a 600 sq ft addition to this house, and adding electric central air heating and cooling. It is a 4 ton unit. (60 to 80 amp heater?)
Here are the two options suggested to me already.
1) The HVAC installer recommended upgrading the outside meter and breaker combination ("meter main") to 200 amps and then feeding the old inside main from one larger outside breaker. He then suggested running a wire (presumably from another outside breaker) the 60 foot distance through the attic to a new 200 amp inside main underneath the central air heater (which is in the attic). This main would also serve the new addition. I will probably move the electric stove to use this new service, since the wiring in the area is now exposed. I assume he would power the outside air conditioning compressor (40 feet away) with a third breaker from the new 200 amp outside main. He suggested 6/3 wire for the 60 foot run through the attic.
After some consideration, I began to think that the single line to the new 200 amp inside main would be overloaded unless it was very large.
2) A suggestion from another individual involved the following layout: Upgrade the outside main ("meter main") to a 200 amp unit. Run one breaker to the old inside main. Run another outside breaker and wire directly to the central heater through the attic (60 feet). Run a third outside breaker and wire through the attic to the new inside main (60 feet), which could be now be 100 amp (20 circuit), since the central heater has it's own circuit. Run the fourth breaker and wire outside the house to the air conditioning compressor (40 feet). He suggested using 4/3 or 2/3 wire for the 60 foot runs through the attic.
Here are my questions:
a) Which arrangement would you use that meets NEC code? Are there more options? b) I would prefer not to change out the old inside main, unless it's of great advantage. c) Also, do I need subpanels for the central heater and air conditioning compressor? d) What gauge of wire is acceptable to use for 60 foot runs through the attic? Should it be enclosed in a pipe? (the attic is vaulted ceiling with very little (2 feet) crawling room) e) Last, is it okay to have a single main breaker/smaller breaker box on the new inside main (60 feet away from outside service) or should it be a subpanel as well?
Sorry to be so long-winded, but I wanted to be thorough. I would *greatly* appreciate any expert help in this matter.
Thank you!
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What you've posted seems confused, as parts don't make sense. I'm hoping you have your breakers labeled wrong, and am guessing what you have is the following in the inside panel:
100A main 60A for stove 30A water heater misc 15A and 20A branch circuits
For what you want, you will need a 200A service and perhaps more (you'll have no expansion to grow w/200A). You may want to go with a 320A service if you're going to the trouble of replacing your service. Both options 1 and 2 are NEC compliant except that 6/3 can only support a 60A panel. If you really want a 200A indoor subpanel, you'll need a 2/0 copper feeder with 4 wires which is huge, and the main panel must have feed through lugs (uncommon). I would lean towards option 2, but it may look ugly on the outside of your house with all the feeders coming out of it. If you have an outside main disconnect (breaker), all the inside panels must have their ground and neutral busses separated. Only the ground bus can touch the chassis on a subpanel, the neutral must remain insulated. If your existing 100A inside panel is not isolated like this, it could be difficult to make it compliant (wires too short).
The central heat and A/C need disconnects, but not necessarily subpanels. If this is a heat pump, the part with resistance heat will need a lot of amps. Best to run a circuit from the main panel to just handle this load (which will probably have to be #4 or #2 copper).
The wires in the attic are sized by the size breaker protecting them and not necessarily length. But with a 60' length, I'd be inclined to stay with the larger choice if a borderline wire size is needed. Wires do not have to be in conduit if a cable type wire is used, but must be protected from physical damage. Your low attic sounds like you may just be able to fish the cable through and staple it down where you can.
When you ask about an inside "main" I'm not sure what you mean. It is OK to have a subpanel inside with its own main breaker, but a main breaker is not required in a subpanel inside your house. If you want a "service rated panel" inside, it usually must have a main. Only problem is, all your "service rated" disconnects must be grouped near each other (can't have one outside and one inside). If you have an outside disconnect, that is the only main you need, and all other should be subpanels. You could have another panel next to that outside disconnect that is also a "service rated" panel, but you usually only do this when you have a larger service than the panel is rated for (e.g. 300A service with a 100A and 200A panel side by side).
Hopefully this helped and didn't confuse you too much. You may want to post again with new questions. I'd recommend talking to an electrical contractor to see what they recommend. Be sure you know the amp requirements of the new heat pump (both inside and outside units) and anything else you want to add that is power intensive (larger range, hot tub, welder,...). Sometimes, HVAC contractors can do some really weird things with power, but then so can lame electrical contractors. Be prepared for the electrical costs to top $1000 for all of this, and even more if your electric utility company charges to upgrade the service drop and/or transformer to your house.
-- Mark Kent, WA
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First, *Thank you* for reading this and taking your time to reply, Mark!
I hired an electrician to come out and give a consult since I wrote the questions. He suggested option 1 at first (200A inside panel for heater and addition, 60' away from outside disconnect) After he left, I checked the ampacity of the wire needed to feed option 1 and was told I'd need 4/0 feeder wire (at $7.50 a foot!) to carry potentially 200amps.
After reading your analysis and calling the electrician back, he said I could optionally run 2 wires (one dedicated to inside heater, one to a 100amp panel) instead of 1 wire to do both. That way I could run 4/3 copper 60' through the attic directly to the heater (heater only) and 2/3 copper 60' through the attic to a 100amp panel for the addition (lights, sockets, stove, dryer, sewerage pump) (instead of a 200amp panel as per option 1), and have an outside breaker for each seperate circuit (total of 4 circuits - old inside panel, new inside panel, central air heater, outside compressor). It intuitively seems to be a better solution to distribute the load over 2 wires instead of 1.
I rechecked my old inside main, and there is indeed a 100amp single throw double breaker for the stove. At least when I throw it, the stove is off, but other lights are on. The stove consists of a separate oven and rangetop. Have no idea why the original homeowners installed a 100amp breaker, but it's there. I'm guessing the wire coming from it is a #6.
BTW, the new central air and electric heater is a Goodman 4 ton 13 SEER conventional unit (not a heat pump) According to option 2 (which is what I'm tending towards now), the heater will have it's own dedicated circuit from the outside meter base and breaker. Should I also have an second inside breaker/disconnect for the heater at the heater location (which is right above the new panel, in the new attic)?
I appreciate your mention of separating the ground and neutral busses on the subpanel. I don't know if the exisiting inside panel is able to be ground and netural separated. I do know that most of the wires going through the exisiting structure do not have a ground wire. It is also good to know that a subpanel can have a main breaker (that was a hard one to find an answer to). Home Repo suggested that a subpanel without a main breaker (main lug?) had to be used if the distance was >10 feet.
I want to be NEC-compliant and am very interested in doing it as properly as I can (and hoping to leave the existing inside panel untouched, minus transferring some of the existing panel's load - stove, dryer, sewerage pump - to the new panel)
Thank you!
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Yes, 4/0 for aluminum, 2/0 for copper. And you must have a 4th equipment grounding wire that is #4 aluminum or #6 copper. Big ugly feeder.

Its actually better cost wise for one large feeder. Safety wise it shouldn't matter as you'll protect the wires with the proper size breaker.

Wow. I'd definitely fix that when you change your power. I've never seen a range that would be allowed to be connected to a 100A circuit. Probably would be wise to double check all wire sizes and the breakers protecting them.

The heater must have a disconnect within sight of the heater. If your main panel or feeder disconnect is within sight of the heater, then you're done. If not, you'll need a disconnect box (but it doesn't have to have a fuse or breaker). Same rules for the outside A/C.

May want to visit here if you have more questions: http://www.selfhelpforums.com/forums/viewforum.php?f &sid974ba858930386 db5be7e2574a3e83
-- Mark Kent, WA
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Having a range on a 100 amp breaker could be dangerous. It shouldnt be wired with #6, but it may feed a subpanel. In my house, i have "pushmatics" and the 100 amp main panel has a split bus. On the "always on (no main)side, there is a 30 for the clothes dryer, a 60 for cooking equipment, (my fryer, stove, oven, and rooftop exhaust blower unit) then there is a 70, that feeds the bottom portion of the panel. The lights and plugs come off that. There is a tap off the bottom (protected by the 70)that goes to a *400* amp "QMQB" style PANELBOARD, that covers all the basement stuff. The owner was an electrician, and had a ""spare"" FPE QMQB board. Oh well... :) ( the FPE is pro-tected by a 70 amp breaker, so i dont worry too much)
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