Upgrading to 300Amp electric service

My homebuilder says upgrading my electric service to 300 or even 400 Amps will result in more "efficient" use of electricity by my appliances. Can one of you experts out there please explain how this is so?

Only if you are planning to use up to 300 or 400 amps, otherwise he is full of BS, sounds like a sales pitch to get you to pay a premium for the extra amps. More important is to get a panel with as large a capacity of circuit breakers as you can, which may take more than one panel to do the job, so that there are a lot of lightly loaded circuits instead of loading each circuit to the max. This will give you more "head room" in each circuit so the ones that end up with a load are not overloaded. Also to provide a separate circuit for each large load or critical load such as a separate line for a freezer, etc.
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On Fri, 7 Apr 2006 16:46:04 -0400, "Eric Tonks"
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I agree with you.
But you remind me of a long time question I've had.
When I lived in a 1930 apartment building, the fuse box in my apt. had 2 slo-blo 15 amp fuses, and in the basement the fuse that served my apt. was 1 slo-blo 20 amp fuse.
I was told this was bad, because 2 x 15 = 30 which was more than 20. I was told the sum of the fuses downstream should never be more than the upstream fuse. Any truth to this????**
I sort of figured first, that the landlord would not rewire the whole building and I needed my 30 amps, so I should keep my mouth shut. second, the building had been working this way since 1930 and there were no electrical fires, and that's still true today, 75 years after construction. and third, the 20 amp fuse in the basement would protect the 12 gauge wire from the basement to the 5th floor. That was its job. But there were sometimes I would use 14 amps through one fuse and 5 through the other, and that would be under 15, and under 20 total so what's wrong with that. Anything higher would blow one fuse or the other.
**If there is any truth to the idea that two 15 amp fuses can't feed a 20 amp fuse, why is it all right for the sum of all my circuit breakers to be greater than the main serving my house. I have cb's totally 200 or more amps now, and room in the box for in the box for 120 amps more. Maybe more. I'll never use anywhere near all of it at once, but if this is ok, why was my apartment setup not ok??
BTW, slo-blo is only 5 or 10 seconds, right? It's more than 1/2 second like non-slo-blo, but no where near 30 seconds, is all of this so?
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Nope. The current is limited to 20A max, no matter what the downstream fuses are. Fuses are sized to the wiring they protect. Period.
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You weren't getting 30A, only 20.
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No surprise -- nothing inherently unsafe in what you've described. Silly, perhaps, but not unsafe.
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Nothing.
Ahh, now that's a different story. Two 15s feeding one 20 is not the same as one 20 feeding two 15s.
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It's just not a problem.
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It is ok, and that's why -- you won't ever use anywhere near all of it at once. For example, the probability is near zero that you'll ever use your air conditioner and furnace simultaneously. It's also quite unlikely that all of the lights in your house will be on at once, or that you'll simultaneously be using all of your appliances.
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It was ok, at least as you describe.
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I never timed one, but yeah, it takes a little while, but only a little.

On Sun, 09 Apr 2006 23:49:57 GMT, snipped-for-privacy@milmac.com (Doug Miller) wrote:
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OK. I'm happy. It's been a long time but I thought one or two people said it was bad at the time, and that 2 or 3 others have said it was bad since then. Whoever did complain to me, it seemed like an absolutist rule that didn't make sense. I'm glad it's not a rule after all.
Thanks. Several more reply lines below, but this was the essence of it.
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Right. My mistake. I really needed my 20 amps. 4 people for a few years, and later 2 people and one room air conditioner. I also worked things out so I could go to the basement to change the fuse in the middle of the night without bothering the super. I think I replaced a blown fuse about 10 times in 10 years. Somewhere between 8 and 18. I vaguely remember a short period where I blew a whole bunch, but I can't remember why. 18 in ten years doesn't seem like too many.
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Compared to I guess 200 amps I have now, I really was not constrained much by having only 20. Washing machine, no dryer or course, gas stove. Plenty of lights, radios, I might have had two tv's on at once once in a while (one in the kitchen), but iirc no roommate (I had about 20) ever had even one tv. I wonder why not.
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I think this is typical for 100's or thousands of buldings in NY. Immigration was high all the time, but especially the 1880's to 1914, I think it was, so there were plenty of buildings nicer than tenements being built by the '30's. The war may have prevented much building in until '45, and after that there was probably more electricity provided for each apartment.
In the garbage room on our floor (where there was a chute that led to the basement, where the garbage was first burned and then later compacted, there was a sticker on the wall: "Save your cans. Defeat the Axis." They only painted this tiny room every 20 years or so -- it didn't seem to get dirty -- and when they painted in 1980, they didn't paint over this.
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I meant to say it the other way. Or I was looking at "feeding" in a different way. But regardless, I didn't mean anything different from before.
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That's what I thought.

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It better not be, because probably most people would be in violation of it. The sum of the ampacities of branch breakers in a main panel is _usually_ higher than the main feed breaker.
[IIRC, the breaker sum in our panel is > 3 times the size of the main breaker.]
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Slo-blos are _specifically_ designed to ride out the startup current surge of a motor - typically 3-5 times higher than the steady state amp rating of the motor. If that takes more than 5-10 seconds (eg: the motor is stalled), the fuse better blow or the wiring might do something real bad (eg: melt).
So, no, you don't want a slo-blow to take much longer than that.

Sanj wrote:
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Rubbish

It only makes sense if your connected load requires it, but has nothing to do with efficiency
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Only in the sense that if larger service entrance conductors were installed you would have less of a voltage drop and losses from resistive heating that you would otherwise under very heavy loads. A lot depends on the length of the drop. If all the facts are known, it can be calculated with reasonable accuracy (the resistance of the SE conductors and the resulting voltage drop as a fuinction of current used).
You would have to be using most of that 300A most of the time to see a difference though. It probably would reduce the incidence of lamp dimming under heavy load conditions.
I don't think it would make any diffenence in your bill whatsoever since metering is done after the SE conductors make it to your house. Any energy lost in the SE conductors as heat (P=I*V or I^2*R) would not be metered.
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It depends on your needs and the size of the home. I know a couple with a 7000 SQ foot home they have two 250 amp main panels. I was told 250 is the largest main home panels available but dont know if this is true.
Frequently main entrance cable around here is alunimum, I would spend the extra for copper from the meter can to the main breaker.
sounds like a big home have you included a standby generator for power failures? thats $ well spent

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Why? The electricity doesn't know the difference.
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Why would it be better spent in a big home than in a small one?

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Actually Al is better for heavy gague service entrance conductors. The metal oxidizes less, it weighs less and it stands up to the elements better than Cu if the jacket is damaged (due to the thin patina of oxide). You only need slightly more metal to get the same resistivity as Cu but these things are over engineered anyway. Al also expands less than Cu which is an advantage for long overhead lines to reduce droop in the summer. Other than that, in a poll, 4 out of 5 electrons don't care what metal they are in. :)
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Rule of thumb, more house, more lights, plugs and loads. A smaller house (~100SF) could justify so much current but it would need a big load like a Kiln or an electrically heated pool.

replying to PipeDown, Mistert wrote: I have a small 1800 sq foot home 2 full bath and 2 old fogies live here retired and i want to go to the tankless Eco 36 but have 200 not 300 amp svce. and we never have 2 showers at once just a load of clothes. Do I have to add more elect'l service?

On Friday, May 25, 2018 at 1:44:06 PM UTC-4, Mistert wrote:
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It's 36KW, so it needs 150A. With 200A, you only have 50A left for everything else. So, what are the other significant loads? AC? Electric ovens? Cooktop? Dryer? Add it up and you'll have your answer. Even one of those other loads and you're close to the limit. I think for most people, tankless makes no sense, for a variety of reasons. Starting with that I don't believe the operating cost savings justify the larger upfront costs. The essential difference is you're eliminating the standby losses of a tank type. Electric tank you can buy one of those extra insulation blankets and pretty much totally enclose it in more insulation which will reduce the losses.

On Fri, 25 May 2018 11:08:39 -0700 (PDT), trader_4
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He might want to think about downsizing the heater to 24KW, understanding that that might limit the hot water he can use at any one time. The things that will end up competing will be an electric range and the dryer but if you have 100a to work with that might not be problem 99% of the time. Only having 50 could be problematic. Without a load calc it is really hard to say what he can do. I tend to agree with you, tankless water heaters may have a very long payback time if you don't have natural gas.
To the OP, have you looked at what the cost will be to upgrade? You can probably just put in a 320a "meter main" change the feeder from there to your existing panel with "4 wire" add a grounding bus or two and feed the new water heater from the meter main. You are likely still talking about close to a grand by the time you are done with the service. It will take a long time to make that back, just saving the lostr heat from youe existing water heater. Remember in the winter, there is no lost heat at all if you are running the furnace.

On Friday, May 25, 2018 at 2:38:36 PM UTC-4, snipped-for-privacy@aol.com wrote:
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The payback is even worse if you have natural gas. They suck up gas like they suck up electricity, so you typically have to run a bigger gas pipe from some big tap off, maybe even all the way from the meter. And gas heats cheaper, so that makes the pay back take longer. Here, the summer gas bill is under $20, which includes hot water and some gas grilling. What you're saving is mostly the standby cost, of the $20, that can't be all that much. Even if it's half, $10 x 12 months = $120. And I just have a basic water heater, for a couple hundred more you can get higher efficiency too. Running gas, the cost of the unit, it's a lot to pay back.
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On Fri, 25 May 2018 15:04:14 -0700 (PDT), trader_4
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It is worse than that. If the furnace is on, there is no lost heat at all. It still goes to warming the house. It is like all of the other energy you use in winter. The only real wasted energy is what escapes the envelope of the house and the hot water you send down the drain.

On 5/25/2018 6:04 PM, trader_4 wrote:
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+1
My well water temperature is 48F.
I can't imagine what it would feel like to be taking a nice hot morning shower and all of a sudden the libtard energy-saving tankless water heater quits working.  Suddenly I'd be standing in a stream of 48F water trying to rinse the shampoo out of my hair. No thanks, I'll keep 50 gallon tank type water heater.

On Friday, May 25, 2018 at 8:29:35 PM UTC-4, Agua Caliente wrote:
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e
hower and all of a sudden the libtard energy-saving tankless water heater q uits working.  Suddenly I'd be standing in a stream of 48F water tryin g to rinse the shampoo out of my
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That's true, with a failure on a tank type, you'd get a more gradual shift that gives you warning. Also, if the power goes out, you have 40 or 50 gallons of hot water that will last for more than a day if you use it sparingly. I guess some of the tankless gas units will fire without power, but not the electric, obviously.

On Fri, 25 May 2018 14:38:01 -0400, snipped-for-privacy@aol.com wrote:
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Can be a pretty long payback on Natural Gas too if you need to replace the meter and upsize the high pressure line from the street. Since gas is cheaper per therm than electricity the payback will be a lot longer because the cost savings are a lot smaller - even if it's the same percentage savings.
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