Which Electrician is right?

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RockyGwen

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Southern Indiana
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Retired
I have a small cottage (480) sq. ft. I am building and I am getting quotes for electricity. I can only have a 100 Amp breaker box with out paying thousands of dollars to upgrade my current system. I want to have all electric if possible. Plan to have a hot water heater, electric stove, refrigerator, microwave and an appropriately sized mini split heating and air system.

One of the electricians says I will be fine with a 100 amp breaker. The second electrician is telling me it will not carry all this. I would have to have stove and water heater run on gas. I am not an electrician just an older woman trying to make a wise decision and create a safe place for my 89 year old mother. I have already been scammed once on this project.

Any help would be greatly appreciated.
 
You are probably not getting scammed by either electrician, It would be rare to be running enough stuff at the same time to overload the 100 amp service, and if you did, all it would do is trip the main breaker. But you will have very little wiggle room for any growth. Heating would be the biggest load, and if several portable heaters were added on top of what the mini split used, and she was cooking a big Christmas dinner at the same time, it could possibly trip the main, which is what it’s designed to do if overloaded.
 
IMO the 100 amp service will be fine. You can always upgrade it in the future if it turns out to be too small.
 
In years past, a 60A service would have been used and likely been just fine.

Well, no mini split or any AC back then. But with the AC, 100 is good.
 
I can't see how the cost of a 200a over a 100a would be considered a 'rip-off'. The labor's not that much more for 200a, and the material itself shouldn't be thousands more.
 
480sparky said:
I can't see how the cost of a 200a over a 100a would be considered a 'rip-off'. The labor's not that much more for 200a, and the material itself shouldn't be thousands more.
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It sounds like she already has the 100 amp service so she would be saving money if she didn't have to upgrade
 
480 sq ft - 100A will be fine. Your 100 A electrician is correct.

I grew up in a 1907 house with a 60 A service installed circa 1914. Over the years added electric stove and oven, microwaves, A/C, pop had a woodworking sop (he never di have a 200 A arc welder though) Mom died last May at 98 YO, had lived in the house since 1945.
The main disconnect had 2ea 60A fuses and big knife switch. That is still there!.
In 2015 I took the disconnect apart and cleaned all the oxide off all component and replaced the fuses, which were over 100 years old and hav NEVER blown. Did replace with 100A fuses as Pop had replaced everything downstream in the 1950s.

PS: I doubt you or you mother will be adding an arc welder anytime or a big 10 HP table saw in a shop, eh. You will be fine with 100A.
 
PS:
Thanks to the mods for not deleting the OP thread.
As said, I also had an elderly mother and allowing this type of non DIY question by the mods shows good empathy.

PPS: GWEN, let us know how your install goes, folks here thrive on feedback.
 
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Might be missing some details. Is this cottage on same property and fed from existing 100 amp panel or new service?
 
RockyGwen said:
I have a small cottage (480) sq. ft. I am building and I am getting quotes for electricity. I can only have a 100 Amp breaker box with out paying thousands of dollars to upgrade my current system. I want to have all electric if possible. Plan to have a hot water heater, electric stove, refrigerator, microwave and an appropriately sized mini split heating and air system.

One of the electricians says I will be fine with a 100 amp breaker. The second electrician is telling me it will not carry all this. I would have to have stove and water heater run on gas. I am not an electrician just an older woman trying to make a wise decision and create a safe place for my 89 year old mother. I have already been scammed once on this project.

Any help would be greatly appreciated.
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I come up with roughly 91 amps as a calculated load and that was using 4800 VA for the heat pump which I believe may be over kill. Either way you look at it you are border line. If you put a new 100 amp service installed up to current NEC you should be fine.
 
This exact same question gets raised in regards to pool houses. Often times 200 amps gets thrown in, but 100 amps has also been shown to work fine

10va per foot electric heat, so 20 amps. 18.75 amps for the water heater. 25 amps for the dryer. 12 amps dishwasher, 6 amps lighting and power on one leg. Stove might draw 20 with broiler and two burners on high. 96 amps tops. Probably will never happen.
 
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