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Discussion Starter · #1 · (Edited)
We recently moved into a 1925 house that has 100 amp service. We are planning on adding a bathroom and completely redoing he kitchen and family area and I have consulted with a number of general contractors on the project for the pieces of it that I don't plan on doing myself, including the rough electrical and plumbing.

All of them have said "Oh, you need to heavy up to 200 amp service." as though that were just an obvious thing. Clearly we need to redo our panel or add a subpanel as the existing one is from the 60's and breakers for it are no longer available.

The estimates for the cost of heavying up seem to hover around $3k. I really don't want to spend this unless I have to, and I'm leaning towards thinking it is not necessary.

The house is 2,000 sq. ft. of finished space, central air, gas hot water heat, hot water, dryer, and range. 1.5 baths (currently) and no rooms with rows of recessed lighting. Living in the house are my wife and myself and our two daughters, 18 and 21, who will be (hopefully) moving out in the next few years. We are modest energy users. We have not tripped a breaker since we have moved in.

Yes, we have a good sized home theater, numerous computers, and I turned the old walled-up garage in the basement into a workshop with oodles of tools. But we just don't find ourselves running masses of electrical devices at once. It's just not how we roll.

How do I calculate if we need 200 amp service? I assume this relates to maximum anticipated draw and is not a function of how many circuits we need/have?

Thanks in advance.
 

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Sparky
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with all gas appliances 100 amps is usually plenty


but if you're redoing your panel/service anyway, going to 200A is usually not that much more money
 

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Discussion Starter · #4 ·
Thanks. Fully loaded I'm getting 71 amps. I guess we don't need it. :\

I would only redo the panel if we were heavying up. I think adding a subpanel for the new circuits we might need for the renovation is more cost effective. Are there reasons to upgrade the panel if it is fully functional and in good working order?
 

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Electrical Contractor
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You don't have to upgrade the "service" even if you want to replace the "load center" --->

If a house has most of its heavy heating done by gas, a 100 Amp service is usually adequate, as you have discovered.
 

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Lic Electrical Inspector
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Unless your house is all electric, you probably don't need it. Sounds like an upsell to me.
 

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If planning on putting in a workshop out in the garage, would be the only reason I can see going with 200 amp. My house was built in/around 1937, and we have 100 amp service. With CFL's, and today's more energy efficient appliances, a home that before needed 200 amp, may be able to get by nowdays with a 100 or 150 amp service. Look at current needs, and then look at future, depending on how much longer you plan on being there. To give you an idea, our panel only has one slot left in a Square D 20 slot, and I have had to use 4 tandem breakers to fit our needs. Yes the panel needs a sub, but currently still in the process of a long drawn out update on this place, but stuck in the middle of a Kitchen remodel.
 

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Lic Electrical Inspector
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You really need to do a service calculation. If all you need is more circuits then install one of the new 60 circuit panels. It will depend on the load.
 

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You really need to do a service calculation. If all you need is more circuits then install one of the new 60 circuit panels. It will depend on the load.
For the OP, since it is a 2000 sq ft home, and they plan on doing a Home Theater, really a 200 amp service would be sufficient, so why do a service calc, when they know what they are going to have in there. 100 amp or even 150 amp would be doing a disservice for the size of the home, and the planned use in the home. For example, my home is only 821 sq ft, with 2 bedrooms. 100 amp is sufficient. If I added a electric range or electric water heater, or even a server farm, I would have to look at going with 150 amp or if I added a workshop in my garage, 200 amp. Everyone's needs are different, but in this case with their needs, 200 amp would probably be the best route for current and future needs.
 

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Discussion Starter · #12 ·
I don't think a few of you later posters have read my posts. I said we HAVE a home theater, are conservation minded, and have been fine in terms of the performance of our electrical service thus far. I don't have any immediate plans to increase our load. The issue is that contractors just seemed to assume that we were going to heavy up as part of our renovation.

I did the calculation, as you can see above, and I appear to be comfortably within what 100 amp service can provide
 

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Ironlight, regardless what the calculator stated, for your size of home, min. by today's standards would be 150 amp, 200 amp for future needs. Do not under estimate what may happen in the future in lets say 20 or so years when the next buyer moves in, or in your case, your needs increase.
 

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If you are adding to finished living space such as finishing a basement, or adding a subpanel to make your garage into a workshop, or add a large built in electric appliance (heaven forbid, a water heater) where none was before, you have to do a new load calculation and this in turn may force you to upgrade to a bigger (150? 200?) amp service.

Load calculation includes among other things a wattage requirement (3 watts) per squre foot.

You should do a load claculation when just upgrading to code e.g. the 2 small applaince 20 amp circuits to the kitchen but here you may get away with not upgrading the serice if you fall short of amps.
 
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