100 Amp vs 200 Amp When do you recommend upgrading from a 100 amp circuit breaker panel to a 200 amp ? I just inspected a 1970 home with 1930 sq ft, someone just put in a new panel, but only a 100 amp. Why not just put in a 200 amp ? Any general guidelines for amperage vs sq ft or other rules of thumb ? Re: 100 Amp vs 200 Amp �The things that will destroy America are peace at any price, prosperity at any cost, safety first instead of duty first, the love of soft living, and the get-rich-quick theory of life.� Joe Funderburk, CBO, CMI Alpha & Omega Home Inspections, LLC Inspecting Upstate SC & Charlotte Metro, NC Angie's List Super Service Award Winner 2013, 2012, 2011, 2010. Could you be talked into moving North East a couple of hundred miles? You sound like my kind of HI. Just did a call where the HI stated that the service needed an upgrade to a 200 amp service on a house that had a 150 amp service and the range, water heater and heat was gas.

The house was 1550 square feet and the only appliances installed were a dishwasher, microwave and a dryer. My recommendation was to leave everything alone. The calculated load came to 82 amps to the best of my recollection. The calculated load came to 82 amps to the best of my recollection. Mike, I am surprised that it was that high with gas heat, hot water, and range. Paul may confirm this but many 100 amp services (at 240V= 24,000 Watts) never get above 50-60 amps draw. So why think the home needs a 200 amp service if it has not been added to or had some major electrical appliance additions, like an electric kiln for pottery. Here we have electrically heated homes of 1500-1600 sq ft meeting code at 100 amps. Better to size the entrance properly than to guess that it needs more power. I find many electricians way oversize the entrance here especially if there is some electric heat in the home, automatically go to 200 amps!! Probably 125 or 150 amps would have been adequate.

This is a waste of materials that may never get used......no wonder copper is up 300%+ and oil is $88 per barrel......conservation is a word that many do not have in their vocabulary. window ac unit recycleOn the Fine Home Building forum, they call the large poorly built homes with all the fixins on oversized lots .....outside air conditioning unit blowing cool air That sounds quite high!! fan not blowing on outside ac unitWhat else eelctrical was in the house? Yes, I have been in homes with a 320/400 service and had (2) ovens, (4) AC Units, (2) Sub-Zero fridges, and all lights on ( 125 Recess Lights ) and so on and everything you could think of plugged in and running....and only read about 185 A on the service......

it boils down to diversification of loads.......and thats a wonderful thing about electricity......The NEC is always going to be a cautious standard...meaning things are always a bit oversized.....take the difference between a standard calculation and an optional method calculation....can be a HUGE difference....and both quite legal. 1550 x 3 = 4650 2 small appliance and laundry = 4500 Microwave and dishwasher (estimate) 2400 Total of all the above = 16550 First 10000 at 100% = 10000 6550 at 40% = 2620 Air conditioner at 7200 19820 divided by 240 volts = 82.85 This 82.85 amp load is not what the service will draw all the time it is only the load that was calculated to size the service with. Electrically speaking...nothing in the NEC says you have to size in regards for the future...in fact their is a myth that you must leave 10% of OCPD space in a panel for future installation...when in fact you can fill a panel to 100%. It is important to take the dwelling at what it is at the time of inspection, if the house is finished and the panel was updated to the 100A and it runs all existing appliances and so on.......you can't force to future needs....as the buyer is buying what the see....not what they want....to see

I agree with you in that you need to make the statement that the panel may not be fine if the client plans on making changes and additions to the dwelling in the future...but as of right now unless you do a calculaion and qualified to do so.....the service may be fine even at 100A.....remember 100A is the minimum size required. As for AFCI and so on......they make AFCI Classified listed breakers that will fit most any brand panel now ( excluding FPE and Zinsco...)...so if their is a breaker for a bedroom in the panel now......making it an AFCI breaker is not a big problem for a client if they wish to update that for their safety... I agree with your premise...and I understand ( remember I am a Home Inspector also ).....but the 100A panel may be fine...heck I see plenty of 200A panels that leave no room for expanding....in regards to breakers but it does not need a 400A service upgrade because of it......so it is very important to understand diversification in electrical services.

.....remember 100A is the minimum size required. Is this required by codes or insurance companies? I did a very small house (550-600 sq ft over a crawl space, no laundry) inspection for a retiring single lady a few years back which had a 10-15 years old 240v, 60 amp entrance. Did the standard calcs by the local codes and it was OK at 60 amps but I warned the lady that the insurance company would want to see a 100 amp service. 3-4 months later, got a call from her saying she finally bought the house but it had been upgraded to 100 amps by the vendor even though the local electrical inspector said it was still alright. The insurance companies have too much power!!!Frequently people want to know how many solar panels they will need based on the size of their home. However, the amount of electricity you use is more important for solar electric system design than the square footage of your home. This is mainly because people’s use of electricity varies in so many different ways.

Same House, Different Energy Situations For instance, let’s say two families live next door to each other in 2,000 square foot homes. A young man lives in Home A with his fiancé; they both work long hours and often spend evenings out with friends. As a result, they don’t use much electricity and pay about $40 a month. In Home B, two parents live with their two teenage children. They are either running the heater or air conditioner and use electricity to filter their pool, meanwhile the teenagers are always on their iPads, opening the refrigerator or watching TV. Since more people live in the house and their lifestyle requires more energy, their electricity bills run at about $325 a month. Importance of Electricity Usage for Solar Panel Design Even though they live in homes that are the exact same size, the family in Home B would most likely need to invest in more solar panels to bring down their electricity usage than the couple living in Home A.  Even if the households were identical in electric consumption, one home may have better solar exposure or less shade than another, which can mean more or fewer panels.

Electricity usage is also important because most utility companies in Los Angeles and Orange County limit the size of your solar system based on the amount of energy you currently use. This number is usually determined by looking at how much electricity you have used in the last 12 months. Just Moved or Building Your Home? Here’s How it Works Of course, there are always some exceptions to the rule. If you have only lived in your home for a few months or want to install solar panels on a home in construction, then most utility companies let us estimate usage based on your home’s square footage. As an example, LADWP calculates this type of average at 2 watts for every square foot. So, a 2,000 square foot home would be allowed a solar array of 4,000 watts.  Depending on the type of panel that you choose, a system of this size would be anywhere from 12-18 solar panels.  Keep in mind, this formula to estimate consumption varies depending on who provides your electricity.