Building new home, need help prepping for electric brewing

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ajdelange

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I was not quite happy with the fact that while the distribution in #39 fits the observed data quite well below 50 amps it doesn't fit that well above 50 and we are trying to use it to see what might happen at 200 amps. So I looked at the data set again up to about 3 this afternoon but this time fit the log of the probability. The figure below shows a much more convincing fit than in #39 and so I am much more confident in its projections.

McLeanWeibull.jpg


While at it I also looked at a data set from up north going back to early October. The results of a log fit to that are in this picture

OgdenWeibull.jpg


The most startling thing to me (the nice fits over the regions of measurement are of course pleasing too) is that while the electrical systems, installed appliances, HVAC gear etc. in the two houses are quite different the shapes of the distributions are very similar and the shape parameters (lambda) confirm this is being numerically quite close. Note that the vertical axis is now in seconds rather than minutes.

The McLean curves predict that 200 amperes would be exceeded for about 10^2.6 = 398.107 seconds per year. It is reasonable to assume that distributed among these 6 minutes there would be a period or periods of time long enough to cause the tripping of a 200 amp fuse or breaker. This reinforces the conclusion that is prudent to have the next size service i.e. 400 amperes. The projected time for demand greater than 400 amps is seen to be 10^-4 sec i.e 100 microseconds. It's clear that a service greater than 400 amps is not necessary and 600 would be absurd. But that is what the pros recommended based on the breakers in my panels.

In Ogden the house is smaller and hasn't nearly so many gadgets and doodads so the loads are generally smaller. The Ogden curve suggests that 200 amps will be exceeded 10^0.8 = 6.3 seconds a year. That is much closer to the edge and I would have been frustrated, had I this perspective, that I could almost get away with a 200 amp service there but I wan't given a choice. The electrician did what he thought he had to against my specific instructions (I was down in Virginia when he installed this stuff). 200 amps probably is the right size for Ogden even so it is so close to borderline. The curve suggests that 400 amp would be exceeded for about 4 nS. I don't think any breaker of fuse is going to pop in that time.

All this is fascinating, at least to me, but I don't see how it is going to be of help to OP as his is new construction and he has no history. So I still think the best he can do is count up the pole-amperes planned for his panels and divide by 4 or go through the details of the code load calculation.

I'd like to thank you guys for getting me thinking about this. This method of looking at the load data has got me confident that it really means something. Maybe I can use it as a basis for suing the electrician up north!
 
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Marc77

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Just to get all the details out there the house will only be a smidge over 2700 sq ft with the basement unfinished (maybe another 900 sq ft there). Two ovens (not a double oven), garage fridge, kitchen fridge, a dryer and the brewery will be the main draws. Yes there will be other draws like hair dryers, other appliances, tvs (4), etc. But nothing that to me screams put 400 amp service in instead of the 200 that comes standard.
 

ajdelange

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The factor that will determine whether or not you need more than 200A is how you heat the place and whether your stove/oven/cook top are gas or electric. If you are going to use gas or oil then yes, you should be OK with 200A service if you have no air conditioning but if you are going to use electric (direct or heat pumps) for the heat and cooking then the story changes. The cheapest operating costs you can realize are with ground loop heat pumps but few want to make the initial investment required. Air to air heatpumps cost much less to install but both use lots of electricity. Figure on about 1400 KVA/ton (a ton is 12 kBTU/hr so you will probably need 5-8 tons). Also how you do backup heat is a big factor. A/A heatpumps usually use electric backup but it is possible to back up with gas or even oil. In any case the correct sizing can vary quite a bit depending on HVAC and appliance choices. Presumably some decisions have been made at this point as to how these matters are to be handled and your contractor should have done a load calculation for you. If not do one yourself using the spreadsheet at http://www.buildmyowncabin.com/electrical/residentialloadcalc.xls. How you decide to handle the brewery load will be a major swinger as a 50 Amp circuit is 1/4 of a 200 Amp service and if you count it as a 100% demand factor load can easily push you over 200 A if you are heating with heat pumps with electric backup. OTOH if you are heating with gas or oil you may well be under 200A even with this load counted as 100%.

Obviously it isn't a 100% load by a long shot but what is it? I believe it should be counted, for the purposes of sizing service, as a 75% load but would have to dig into the NEC to confirm that.

I strongly recommend playing around with that spreadsheet as you will gain insight as to what the consequences of you equipment choices are just as playing around with a brewing spreadsheet gives you insight into the consequences of your grain choices.
 

lschiavo

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Obviously it isn't a 100% load by a long shot but what is it? I believe it should be counted, for the purposes of sizing service, as a 75% load but would have to dig into the NEC to confirm that.
I would probably include it as an electric range/oven. If you have other Electric cooking appliances, it will be derated based on the total number of appliances.
 

itsnotrequired

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i would be amazed if a place in kansas city had only electric heat. even with an electric water heater, 200 amp should be plenty for a 2700 sf home, provided they aren't running an electric kiln or greenhouse or some other unusual residential load. i have about 3700 sf finished at my place with a 200 amp service. electric oven and clothes dryer, plus an electric sauna and the brewing system. i haven't batted an eye during brewing, even in the summer when the a/c is jamming. i suppose if i was brewing, drying clothes, someone was taking a sauna and baking a turkey in summer with the a/c on as well as all the lights, maybe there would be an issue but let's get real here...
 

ajdelange

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I feel somewhat as if I am beating a dead horse here but what he has to do does not depend on what would amaze any of you or exceed your personal feelings as to how services should be sized or how big your houses and panels are (though information on this is useful for insight and interesting). What he needs to do is size the service such that it will get past the permitting process, the utility and ultimately the inspector. Clearly whoever pulls the permit should do the calculations but I still encourage OP to use the spreadsheet mentioned in #44, be he the guy that pulls the permit or no, to get some idea of how the choices he makes may influence the required size of the service. To anyone reading this who decides to try the spreadsheet I'll mention that when the pop-up instructions and labels refer to 'Column C' that does not mean column C of the spreadsheet but rather column C of table 220.55.

"Amazing" things do happen, especially when we stick 50A circuits for brewing (or whatever) in our houses. I have mentioned that I have a house which is, I'm sure, under 4000 ft^2 that has 600A service. When I was told that I needed 600A service I was indeed amazed. But I just did a load calculation for the place and per code the load is 477 amps. This is because there are 2 heat pumps one of which is backed up by electric, electric space heaters in an out building and in the old part of the house and (3) 50A outlets. Interestingly enough I can now prove to the satisfaction of the NEC based on actual load measurements that my required service size is 400A which common sense dictated from the start. But the rules are the rules and we have to follow the rules.
 

itsnotrequired

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don't get me wrong, i'm not advocating 'winging it' or using personal preferences to size a service. whatever it takes to get the permit is what it takes. the nec is straightforward for most of sizing a service (e.g. lighting load, laundry load, small appliance branch circuit, etc.) but is a little vague in others. and this is intentional, it is simply not feasible to dictate clear direction for every possible installation out there. a classic example is the requirements of 220.14(C), which dictate how motors need to be accounted for. for example, i have a 30 gal aquarium with a little pump in it, clearly a motor. it is plugged into one of the general receptacles in my living room. do i need to include that 'motor' as a stand-alone item in the calc? or since it is plugged into a general receptacle, is the load already accounted for in the 220.14(J) allowances? there are dozens of little nuances like this and can result in fairly decent swings in what the service size calcs out to be. when in doubt, get your electrician involved and they will tell you what you need.

also a couple issues with that spreadsheet. first one i noticed is the general lighting load calc. yeah, load is 3 va per sf but that is only a 100% demand factor up to 3000 sf. above that (up to 120,000 sf), lighting load is calculated at a 35% demand factor (or 1.05 va per sf). spreadsheet doesn't account for this, will make the service appear to be larger than required. i don't deal with residential electrical permitting that often but i can't say i recall a permitting authority asking for loads like mini fridges and non-fixed microwaves needing to be specifically included in service calcs. not an inherent problem to include them but this likely inflates the load to be greater than what code would typically require.

tl dr, but to the op, mention to the electrician your brew system, the load and how you plan to use it. more than likely, they are already planning on a 200 amp service at a minimum and aside from other wild electrical loads, you should be fine.
 

ajdelange

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it is simply not feasible to dictate clear direction for every possible installation out there.
So what do you (the NFPA) do in a case like this? Be very conservative and that's what they do. In the case of my house up north and based on three months history of load including a darn cold December, the max I drew was 140 A and yet the spreadsheet tells me that for purposes of sizing the service my load is 428 A (without the 3 50A outlets) and I need 600A service. The historical data, if I try to fit a probability distribution function to it which I have done as shown in earlier posts, suggest that the probability of a load bigger than 400A is about 10^-18. To put this in perspective the universe is estimated to be 4.35495e+17 seconds old. The expected number of events at this probability level in the entire history of the universe is, thus, less than 1. To put it in perspective another way, if I gave you 60 pennies, told you that a particular sequence (HTTHHTHTTTH.....) spelled the end of the world and had you flip the coins the probability that you would arrive at the disaster sequence would be about 10^-18. But it's not 0! (that's an exclamation point - not a factorial sign). On your first try you would come up with some sequence other than the disaster one. It has the same probability of occurring as the doomsday sequence (10^-18) but it did occur.


also a couple issues with that spreadsheet. first one i noticed is the general lighting load calc. yeah, load is 3 va per sf but that is only a 100% demand factor up to 3000 sf. above that (up to 120,000 sf), lighting load is calculated at a 35% demand factor (or 1.05 va per sf). spreadsheet doesn't account for this, will make the service appear to be larger than required.
In fact it does handle this correctly. The issue I have with it is that it does not make this at all clear. Enter 1000 ft^2 in the square footage cell and note that the load indicated 3 kVA. Also not the service load in the summary box. Now increase the floor area by 1000 ft^2. The General Lighting Load cell goes up by 3000VA but the service load box by only 1050 which is 35% of 3000.
 

itsnotrequired

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so if i understand correctly, the likelihood of you exceeding 400 amps is very small but you did exceed it. my counter would be...so what? worst case scenario is the main trips and you reset it (would suck if you have fuses). is it worth being ultra-conservative for that one event? i would say no but that's me. i guess what i am trying to say to the op is that if the electrician suggests a 200 amp service, no need to believe he is some kind of quack and press him hard for the 400 amp. who knows what electric demands will be 30 years from now so feel free to go bigger but in my opinion, no need to feel like you are rolling the dice on a 200 amp service.

i took a closer look at that spreadsheet and you are correct, it does account for it. not super-obvious but it is there. my other commentary about mini fridges and the like still apply.
 

doug293cz

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OT question for the code wonks: How do the super efficient LED lamps affect the lighting load assumptions? Or, is the code behind the times? I have swapped out all the incandescent lamps in my house for mostly LED, and maybe a few CF's.

Brew on :mug:
 

itsnotrequired

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OT question for the code wonks: How do the super efficient LED lamps affect the lighting load assumptions? Or, is the code behind the times? I have swapped out all the incandescent lamps in my house for mostly LED, and maybe a few CF's.

Brew on :mug:
zilch. still need to size for 3 va per sf, even if you plan on using candles for light. after all, what's to prevent the owner of the home after you from pulling out their old incandescents and removing the leds? i'm sure code will catch up eventually but this is where we are at...
 

ajdelange

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so if i understand correctly, the likelihood of you exceeding 400 amps is very small but you did exceed it. my counter would be...so what?
So what for sure as I have 600A service.
worst case scenario is the main trips and you reset it (would suck if you have fuses).
I do but at least the main disconnect is indoors at that house.

is it worth being ultra-conservative for that one event?
Remember that I wanted 400 Amp service but was forced into 600 by the electrician and utility and the fact that I was not there to yell and scream when this industrial scale gear was installed. The amazing thing about Quebec (actually, there are many amazing things about it is that they don't seem to have inspectors. The insurance companies seem to assume their role.


i would say no but that's me.
I was really more concerned about whether a 200 Amp generator was sufficient. Measurements show that it is though the probability of going over 200 amps and having to shed a load is much greater (10^-8 -still very small) [/QUOTE]

i guess what i am trying to say to the op is that if the electrician suggests a 200 amp service, no need to believe he is some kind of quack
Based on my experiences with electricians I can't agree. What we are really talking about here is engineering the electrical system and electricians aren't engineers. Now admittedly I did some unusual stuff which was beyond the experience of those electricians but they have worked on some amazing places up there. I've also had electricians here who claimed to have worked on the CIA's new building but couldn't read a one-line diagram.

and press him hard for the 400 amp.
I'd want to qualify the electrician somehow. If OP isn't an engineer I can only suggest hiring one (I know - more $) and perhaps with the scope of his project it isn't worth it.


who knows what electric demands will be 30 years from now so feel free to go bigger but in my opinion, no need to feel like you are rolling the dice on a 200 amp service.
That's a very good point. It isn't that big a deal to upgrade a service really. Yes, you will save some money in the long run if you oversize now but OTOH you may never expand.

i took a closer look at that spreadsheet and you are correct, it does account for it. not super-obvious but it is there. my other commentary about mini fridges and the like still apply.
As you pointed out the code itself allows more than one interpretation in such cases. We can hardly expect the spreadsheet to do better.
 

itsnotrequired

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of course, if the utility, jurisdiction, etc. says you can't put in smaller than a size 'x' service, then that's what will be required. assuming 'normal' electrical loads (brewery included), a home of the op size in his geographic location should be fine with a 200 amp service. that's all i'm getting at. any electrician worth a lick is more than qualified to size a service, they don't need to be licensed professional engineer.

you surely must realize that your 600 amp service is an extreme outlier. can't say i've ever seen a 600 amp service at a residence, save some giant mansion or some other extreme electrical situation.
 

ajdelange

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Wish I could share your confidence in electricians. I finally found one that is indeed "worth a lick" and even he had to have the service entrance requirement explained to him. What sets him apart from the crowd is that he listens.

I realized from day one that 600 amps was too big but was told by the electrician and utility that I had to have it. If the utility says they won't provide 400 amp service to you you take 600 (there's an old story about onion soup). Now the house does have lots and lots of outlets, two heat pumps, 5 electric space heaters, electric backup for one of the heat pumps two laundries, two electric driers and (3) 50 amp outlets sewage ejector pump, and well pump and if you put those into the NEC algorithm, especially the standard algorithm, you go over 400A. But if you look at the actual loads the rule is that you must size for 125% of the maximum average 15 minute load plus whatever you plan to add. So if I went in and said I wanted to add a hot tub that drew 25A my service requirement would be 122.7 (max 15 min avg load) + 25 = 147.7 so I would have been OK with the original 200A service that was there even before I added on. What this proves, if anything, is that my family's use of electricity is not consistent with the NECs assumptions. Our load factors are much less, There aren't as many of us as the NEC assumes there are per square foot, per clothes dryer etc. Another factor is that all the lighting in the new part is LED and tungsten in the old part has been replaced by LED when ever one burns out so the lighting load that goes into the NEC calculation is too large.
 

ajdelange

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OT question for the code wonks: How do the super efficient LED lamps affect the lighting load assumptions? Or, is the code behind the times? I have swapped out all the incandescent lamps in my house for mostly LED, and maybe a few CF's.
As noted, no provision is made. At first blush it would seem that the code is simply behind the times on this but after a little thought it occurred to me that LEDs and CFs impose an additional 'load' on the utility's equipment and that is a current load at 180, 300,420...Hz. The eddy currents induced by these frequencies result in greater heating of transformers and some other equipment and so gear for a say, a 50 kVa load would need to be sized at greater than 50 kVa if these harmonics are present. THD (the percentage of total current which is harmonic current) at my house in Virginia runs 10 - 20% most of the time but can spike much higher for some loads (I don't know what they are but am guessing its when rooms with large numbers of CF lamps or LED lights are switched on). This is definitely considered in industrial settings (I have had to certify that equipment going into a government facility had to have a harmonic current draw less than some percent) but is not, AFAIK, at issue for residences - yet.
 
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