200 amps enough?

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Old 06-12-09, 01:08 PM
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200 amps enough?

Hey Guys,

I知 rewiring, installing recessed lighting, and upgrading the panel on my 3 bed, 2 bath home in California. I知 wondering if a 200 amp panel is enough for the home? Keep in mind, I will hopefully be installing central air and a master suite/bath in the future. I知 lower than an electrical novice, but here what doesn稚 make sense to me:

3 bed rooms 15 dedicated amps each
2 Baths 20 dedicated amps
Garage 20 dedicated amps?
Laundry 20 dedicated amps?
Kitchen 120 dedicated amps
Living/Dining 20 amps
Total: 215 amps

This doesn稚 include 15 amps for the central heat, and 15 amps for the water heater. Obviously, there isn稚 full load on all the circuits, and the water heater, and central heat could be tied into one of the circuits, but doesn稚 that increase the chance of those circuits tripping. Lastly, there doesn稚 seem to be any space left for expansion. Am I totally missing something?

Thanks
 
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Old 06-12-09, 01:16 PM
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The demand load calculation is based on the square footage along with the size and number of electrical appliances. Adding up the ratings of the breaker handles does not properly size your service. If you were to do that houses would end up with 6-800 amp services.
 
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Old 06-12-09, 01:26 PM
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Well, yes sort of..you are. Just because a circuit is on a breaker rated for 15, 20, whatever amps..doesn't mean it will be drawing that much.

For instance...say you have a range that requires a 40 amp circuit...you would have to have all the burners on high, AND the broiler and bake element running, to even approach what the required circuit capacity is. Do you think that would ever happen?

Same with a bathroom. If the bathroom is on its own 20 amp circuit..you could have a 1500 watt blow dryer running...and still have about 7 amps capacity available. Now, if you have 2 baths sharing a 20amp circuit...no you couldn't have 2 1500 watt dryers running at the same time.

Most panels have much more load (by adding up breaker ratings)..than the actual capacity of the panel.

No expert by any means...but I kind of wonder about a couple of your statements...15 amp for heat? You mean for a gas furnace or similar? And the 15 amp for water heating seems way off if its an electric WH.

Also..as I understand..furnace, A/C, water heater, range...any large stand alone load..need to be on their own circuit/breaker rated for the appliance.

I believe the correct term is a Load Calculation...where you actually plan for what will be operated and when...then plan the circuits accordingly.

As I said...no expert...just trying to help. Someone may have posted as I was typing
 
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Old 06-12-09, 02:58 PM
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That makes sense, but does that mean that 200amp panel will allow for more than 200amps worth of breakers?
 
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Old 06-12-09, 03:03 PM
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Sure....you can get 200A panels with 40 breaker slots (or more) as I understand. I have a 100A panel here with 24 slots I believe. So I could put probably 480A worth (or more) of breakers in...but my main would trip if I tried to pull that much.

Thats why the main breaker is sized to the panel capacity.

Unless you have some really extreme needs...200A should be plenty. My last house (2400sf, 2 story colonial, 4 BR, 2 1/2 bath, A/C, spa, electric clothes dryer, gas appliances) did just fine with 150A service.
 
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Old 06-12-09, 03:12 PM
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In my opinion a 200 ampere service should instead be called a 48 kilowatt (48,000 watt) service. You must remember that all of the 120 volt loads are more-or-less equally divided between the two "hot" conductors supplying 240 volts.

My 200 ampere service has a total of 560 amperes worth of single-pole circuit breakers in the main panel and an additional 190 amperes worth of single-pole circuit breakers in the auxiliary panel. Of course the auxiliary panel is fed from a two-pole 60 ampere breaker in the service panel so the maximum I could "draw" on any combination of loads would be 60 amperes per pole. The same maximum draw would be 200 amperes per pole on my main circuit breaker in the service panel yet I seriously doubt that I have ever had more than a 50 ampere total load on each of the two poles of my service in the almost ten years that I have lived in this house.

So the answer is, "Probably not." when you ask if you need larger than a 200 ampere service.
 
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Old 06-12-09, 03:13 PM
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Originally Posted by mrshikadance View Post
That makes sense, but does that mean that 200amp panel will allow for more than 200amps worth of breakers?
Yes, you could easily have 500-600A worth of branch circuit breakers in a 200A panel. The rationale is that every single appliance, light and receptacle will never be in use all at the same time. The reality is that a rather small percentage of all possible loads are active at any given time. The "demand load calculation" uses a worksheet with all of the appliances in your home to estimate what the reasonable total load will be at any given time.
 
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Old 06-12-09, 03:25 PM
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Well, heck, these guys are just hanging out and posting replys left and right...lol. I'll leave my miniscule cents out of it...


Oh...but still..what about my questions about the WH and heat? Just to assuage my curiosity?
 
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Old 06-12-09, 03:49 PM
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Originally Posted by Gunguy45 View Post
I kind of wonder about a couple of your statements...15 amp for heat? You mean for a gas furnace or similar? And the 15 amp for water heating seems way off if its an electric WH.
The heat is probably a gas furnace with electric ignition and air handler -- 15A is a common size for this. The water heater is a little atypical at 15A but could be electric ignition and induction blower on a high-efficiency or on-demand gas unit. 15A would be far too small for an electric water heater.
 
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Old 06-12-09, 03:52 PM
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Ahh..thanks Ben...I kind of thought of the heat answer, but didn't think of the power vented gas WH...never dealt with one.
 
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Old 06-12-09, 03:52 PM
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Of course I have no idea of what the original poster has for heat or hot water but my gas-fired forced air furnace runs quite well with a 15 ampere circuit. In fact, if I remember correctly it take about 8 amperes when lighting and about four (or less) when firing. My water heater is a "standard" constant pilot gas model so it take no electricity but a power-vented gas water heater might have a dedicated 15 ampere circuit.
 
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Old 06-12-09, 09:04 PM
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I use this example all the time:

My bosses lake home (average sized house) Main service is in detached garage since that was built first. Later he built the house. Ran 100 amp sized feeders but only had a 60 amp breaker so he installed that to keep him building. Home was finished and never changed the 60 amp breaker.
Fourth of July weekend they were running a double oven, electric cook top, clothes dryer, some general lighting, A/C (with fan) and maybe the water heater when the 60 amp breaker finally tripped.

Even with the above loads, they are not using the full rated current. Most cases you will not use the full rating of each branch circuit all at the same time. You will be fine with 200 amps.
 
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