Will 150amp service be enough for home

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Old 02-01-10, 02:26 PM
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Will 150amp service be enough for home

I am buying a new home (150 Amp Service) and considering installing a tankless water heater. I am in between two models right now, and I want the one that will not overload the system. I would like to use the bigger model as long as I don't overload the system. Little help from an electrical guru would be greatly appreciated.
Model 1
240v 19.2 watts
Amps 2 x 40 Minium Breaker 2 x 50

Model 2
240v 24 watts
Amps 2x 50 Minium Breaker 2 x 60

Here is what I have in the CB Panel
1 Bed Room 1&2 15amps 2 Bed Room 3&4 15amps 3 Master Bedroom 15amps 4 Garage 15amps
5 Family Room 15amps 6 Washer 20amps
7 WP 15amps 8 Frig 20amps
9 Master Bath 15amps 10/12 Grinder 20amps
11 Foyer 15amps 14/16 Well Pump 20amps
13 Back Island 15amps 18 Small Appliances 20amps
15 Nook 15amps 20 Microwave 20amps
17 GTO 20amps 22/24 Dishwasher/Disposal 20amps
19 Bath 20amps 26/28 Dryer 30amps
21/23 Hot Water Heater 25amps 30/32 AC Handler 60amps
25/27 Range 40amps
29/31 A/C Comp 60amps
 
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Old 02-01-10, 02:32 PM
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Originally Posted by jagretzky02 View Post
Model 1
240v 19.2 watts
Amps 2 x 40 Minium Breaker 2 x 50

Model 2
240v 24 watts
Amps 2x 50 Minium Breaker 2 x 60
These are kW by the way -- 19.2kW or 24kW (kilowatts).

26/28 Dryer 30amps
21/2330/32 AC Handler 60amps
25/27 Range 40amps
29/31 A/C Comp 60amps
These ones worry me for overloading your service with the tankless water heater plus all of these electric appliances. If you had a gas dryer and cooking appliances or a smaller A/C, I would be more comfortable with the tankless. Typically the tankless heaters do not perform well on services less than 200A, and in many cases require upgrade to a 320A.

Could you also let us know the square footage of the house and the typical usage (single person, big family, etc)? How likely is it that hot water and other appliances run at the same time? For example somebody in the shower while somebody else is cooking or doing laundry.
 
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Old 02-01-10, 03:01 PM
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The house is a 2005 and the square footage of the home is 1972 and will be occupied by me and my wife. I think the only thing that I would have running while taking a shower is the AC and possibly the dryer.
 
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Old 02-01-10, 03:18 PM
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Everything is electric, which leaves little room for expansion, and possibly not enough for all the appliances. Go with 200A. Little difference in material cost, and probably not much in labor. If current service is less than 150A, you need a new drop and a new pan for either.
 
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Old 02-01-10, 03:35 PM
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So all I would have to do is have the 150 amp breaker panel changed out with a 200 amp panel, or is it more complex than that. Also what do you mean by drop pan.
 
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Old 02-01-10, 07:15 PM
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No, everything would need to be replaced from the main panel up to the power company connection. The "drop" is the cable that powers your house from the pole; it is called a "lateral" if you have underground service. The "pan" is the box where the meter is installed.

You can do a formal "demand load calculation" (or hire an electrician to do one), but my gut feeling is that the 150A service is too small to support a tankless heater in addition to the other electric appliances.
 
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Old 02-01-10, 10:00 PM
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I am on the same page as Ibpooks is and I really serious doubt the 19.2 Kw tankless electric waterheater can handle the 150 amp service and I am pretty sure it will be a good chance it will trip if you have dryer and Central air going it will trip no question asked.

I have done a bit of service upgrading for the customer whom used tankless waterheater { electric verison } and most were not too thrilled with the price due I have to install either 320 amp { 400 amp resdentail verison } or larger and the cost is not cheap at all.

I will not bother at 200 amp level unless you have 320 service which it will typicaly have either 2 X 200 amp panels or single 400 amp panel ( more expensive }

What more to this mix is the POCO { power company } are getting stricter with electric tankless waterheater due they get too many burnt out transfomer from overloading plus also will see light flickering every time the electric tankless unit kick on .

Did you ever think about using gaz verison ?? { if your local codes do allow that }

Merci,Marc
 
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Old 02-02-10, 11:17 AM
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One option might be to keep the 150 for the house and add a parallel 100 or 150 for the tankless. No need to change out the other panel.
 
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Old 02-02-10, 05:18 PM
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two 200A service but only one 25 KVA transformer

yah, similar problem here.
My friend has a two units property. One is 3000 + squre feet; the other one is 1000 + sq. feet;The land is 2.5 arc. Also, there is a empty land of more than 10 arc surounding the property. The empty land is a potential for future house construction.

The property has two separated service line with 200A each connected to each unit. But the pad-mount transformer is only 25 KVA 120/240 12000hv (65 C rising) . Does anybody believes it is enough? Anybody think the power company had made a mistake to install the transformer with less KVA rating?
What should my friend do? should my friend call the power company to request a replace ment of a 50 KVA transformer or higher ? since there is a potential that more houses will be built in this block.

Any respond would be make be feel better to have the confuse solved.

Thanks.
 
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