is 100 amp box enough? (all elect in house)

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  #1  
Old 11-11-10, 12:22 PM
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Question is 100 amp box enough? (all elect in house)

Ok. So I'm rewiring a house I'm buying on contract. I'm changing to elect heat and water. Here's a rundown of each circuit.

HEAT
10g 30amp supplies 2 heaters. One 16.7a (living room) and one 8.3a (bathroom). This is 6k watts heat from wall mount fan forced 240v heaters. This is 25a total.

12g 20amp supplies 4 heaters. Two 30" baseboard 240v and two 4' baseboard 240v. This is 15.3a total.

OTHER STUFF
Bathroom 12g 20a circuit supplies 1 lights, 1 switches, 2 outlets
Living room 12g 20a circuit supplies 3 lights, 3 switches, 6 outlets
Dining room/porch 12g 20a circuit supplies 3 lights, 2 switches, 7 outlets
Kitchen 12g 20a supplies 3 outlets, 1 light, 1 switch,
Water heater 10g 30a to the elect water heater
Stove ?g (org wire) 50a to the elect stove

We will have a ceiling fan, fridge, a lamp, computer, 3 tvs, and other small appliences.... no elect dryer (until next summer or later) and no elect dishwasher. The house is 950 sq ft and some 10ft some 8ft ceilings. Is 100a main enough for what I'm doing? All wiring is done properly and bathroom is gfci. I need to be moved in by Monday and the elect company is coming out tomorrow. I hope not to have to upgrade as I don't have the materials I need but if I have to, I have too..... I been reading this forum all through my projects and thank you guys for the great tips and advice!
 
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Old 11-11-10, 01:52 PM
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Originally Posted by rad85camaro View Post
10g 30amp supplies 2 heaters. One 16.7a (living room) and one 8.3a (bathroom). This is 6k watts heat from wall mount fan forced 240v heaters. This is 25a total.
You might want to check the details on that one -- 5,760W is the maximum allowed baseboard heat on a 30A circuit. Still that's not very much heat for 950 sqft unless you live in a warm climate. Do you have any AC units to account for?

Dining room/porch 12g 20a circuit supplies 3 lights, 2 switches, 7 outlets
The dining room can't share a circuit with the porch or lighting if this is new work, okay if grandfathered old work.

Kitchen 12g 20a supplies 3 outlets, 1 light, 1 switch,
You might need a second kitchen circuit depending on the status of the dining room circuit above.

Stove ?g (org wire) 50a to the elect stove
A standard range is 40A breaker with #8/3g cable. High end models do require 50A breaker with #6/3g cable.

The house is 950 sq ft
I'm coming up with under 20kW rough calculation; you should be okay with 100A service which provides 24kW.
 
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Old 11-11-10, 02:05 PM
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The porch is enclosed. Its more of a game room than a dining room on the front of the house where the porch is.
So I may have to run a second 10g wire for the second heater in the bathroom...
All my lights will be florasant lights.
There are 2 fan forced heaters and 4 baseboard heaters. I am hoping this is enough for the whole house. (Bathroom and central living room with fan forced and bedroom 1, bedroom 2, front dining room (game room), and kitchen all use baseboard to help heating. Each heater has its own thermo.

So with heat on and if I go to cook my 100a main should be enough and not kick?

Also I'm in indiana and maybe a window ac later on but not for a long while. I'm fine with fans and windows

Thanks for the fast reply!
 
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Old 11-11-10, 02:34 PM
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If you were in my area I would ask why all electric. Electric would cost you 2-3 times as much as gas. Of course in my area AC is a necessity so different places different situations.
 
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Old 11-11-10, 03:17 PM
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Originally Posted by rad85camaro View Post
There are 2 fan forced heaters and 4 baseboard heaters. I am hoping this is enough for the whole house....
Also I'm in indiana
I'm concerned you might not have enough heat installed. You've got about 8000W which works out to 8.4 watts/sqft for the house. I consider 10W/sqft to be a minimum for heating with something like 12-15W/sqft better for really cold days or if the building doesn't have great insulation or a lot of windows. The tall ceilings also will require more heating than normal; a 10' ceiling is 20% higher so you need 20% more heat. I'm in Michigan so you are a little further south than me, but the winters aren't that different.

We don't have a lot of all-electric heat up here, so I'll make some gas/electric converstions. Your size house would usually have at least a 60,000 btu/h output gas furnace which is equivalent to about 17kW of electric heat, about double what you have.
 
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Old 11-11-10, 03:29 PM
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All new insol in ceiling and walls. The house was down to studs when I got it. Windows are covered in plastic inside and out. I know I'm cutting it close but with a fan to help stir the air plus the house is an "open" design. There are 2 bedroom doors and a bathroom door. Other than that everything is open so I figured heat will flow. Total I have 9000 to 9500w of heat. I can't do gas because I'm on a time line and have to be in by Monday. (No way around it I have to be in by Monday)

I just need to make sure the 100a is enough since the power company is coming tomorrow and I want to have everything done. All my wires are already run. I just want to make sure the 100a can handle it for right now. Thanks for all the help guys!
 
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Old 11-11-10, 04:01 PM
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Why not a double lug 200 amp meter can? That way if later you need more power you can easily add a second panel.
 
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Old 11-11-10, 04:08 PM
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What's that mean? I'm new to wiring just been researching as I go
Also I just need to know if I can let the power company go ahead and hook up the 100a for now or do I need to change anything before they get here tomorrow? There's already a 100a box in the house. I just don't know iif I am ready for them to come hook me up or not lol I have all my wires to the box. Now just have to unhook what was already there and hook my wires in. I removed all the old wiring and ran new.
 
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Old 11-11-10, 04:12 PM
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Depends on the area, but in my area the power company will not connect anything until the service has passed inspection from the city or state inspector and he has signed the green approval sticker on the can and panel.
 
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Old 11-11-10, 04:18 PM
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Here its from the box out. With what I have going on will the 100a be enough? There are already running from the pole in. They said if I used 200a they have to wait until I replace all heavy wires from box to meter to top of pole. If I used 100a then they just hook pole to meter and cheak to box. I am set for 100a install tomorrow. Is the 100a enough for the circuits in my first post? Trust me after this ill have lots more questions as I go forums are the best resource!
 
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Old 11-12-10, 10:49 AM
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I think a 100A service is okay for what you have listed now, however if you find out that your current heating situation is not enough I think you might need more than 100A to stay with all-electric.
 
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