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Around these parts I haven’t seen new constrction with 100 amp in many years, although that is the “legal” minimum allowed if new construction or updating the service, say from 60 to 100 amp. I also see it if someone is simply updating a deteriorated SEC and I see it on flips.

Any more the smalled I see is 125 amp and always on condos with gas appliance.

The norm around here for new construction is usually 150 or 200 amp. And a few times a year I’ll see 300 or 400 amp as well, usually is houses 4k sqft and larger.

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My home was built in 1975 and had 200 amp service. I upgraded to 400 amp a few years ago when I built another garage.

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Even a large size house rarely tops 60 amps in use.

You guys must be inspecting sheds with only 400 amp services. I am working on homes with 1200 and 1600 amp services.

This is an example of where two code rules converge. You have the 83% rule that you’ve mentioned and the next size up rule that I mentioned. Take for example a 200 amp service in a non-dwelling. You cannot use the 83% rule because it’s a non-dwelling so it seems that #4/0 is too small but you can use the next size up rule so with #4/0 Al @ 180 amps you could still could possibly use a 200 amp OCPD same as in a dwelling. Same result but two completely different code rules.

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That’s larger than many small/medium commercial buildings. Homes with that requirement generally would be the exception and not the norm. Likely 40k plus sq. feet I would guess.

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was it an all electric home Joe ?

Yes, it has 2 electric furnaces and 2 heat pumps. They ran NG up my street a few years ago. I had NG ran to the garage I built and put in a horizontal furnace in the attic. I continued the line to the house and stubbed it off in case I want to change out the electric furnaces. Haven’t done it yet😙

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when You mentioned the panel sizes I assumed so…my first house with a 200 amp service was a late 70’s or early 80’s all electric split with an electric furnace…The house Im in now is a 2018 build 2000 ft ranch with electric HW, range, dryer and ac but gas furnace it has a 150 amp panel…

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Wow! Clearly I work in some last century urban area. (No doubt explains all the hand-crank horseless carriages around here.) The biggest service to a residence that I’ve ever encountered was three separate 200amp services coming into a 7000sq ft home. The biggest home I ever inspected at 14,000 sq ft only had two 200amp services coming in.

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I wired a lot of houses in the 1970s and 1980s, well within your 60 year timeframe. Probably 95% had a 100A service. Some were only 60A. I do a load calculation on every job. The calculations have remained essentially the same for the past 60 years. Not many houses need more than 100A, not then, and not now.

The demand for electricity in a home, all else being equal, is going down, not up. During the gas curtailment of the mid 1970s, many homes were built as all electric because they had no choice. They still only needed 100A service in the majority of those homes. Many of those homes were converted to gas when we could start using gas again so they had plenty of extra capacity.

Even though demand load calculations haven’t changed, the loads have. Modern appliance use much less electricity today than at any earlier time. The lighting load alone is dramatically lower than in the past. Refrigerators, clothes washers and dryers, televisions, and almost anything else that you can think of uses much less electricity than 60 years ago.

Any home inspector who wants to play electrician and comment on a service size being too small (which is outside the scope of an home inspection) needs to back up that up with the demand load calculations.

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The loads have absolutely changed. Hot tubs, heat pumps and EV charging were not part of homes in the 70s. Homes have gotten larger and now have multiple heat pumps or larger units. With areas banning natural gas i don’t see loads going down. Some EVs are now looking at 100 amp circuits to charge your truck.

Finished the basement in this house about 15 years ago and still could only calculate 186 AMPS.

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I’m glad when I can lighten up your day. Is that a Lake Erie Mosquito?