Update, I submitted the load breakdown to the POCO last night, just want to get this submitted and schedule the buildout. If they don't like any of it, they will come back and ask for more information.
I ended up estimating the breakdown to about a full total of 65kW, which is still quite high but I feel could be somewhat realistic if we have parties or visitors and guests and things are full-tilt at the house. Odds of that happening are very low.
All replies are appreciated! Even the snarky ones
See my replies in line, and my note at the bottom for more info...
Just to be clear.....
The factoring kind of goes the other way. Just for argument sake, consider this...
Is you came up with 96kW of load devices in your house presuming they would all be on simultaneously. Then considered the fact that with WON'T be on simultaneously so a 25% rating was appropriate, you would need 24kW of service capacity.
Alternately, turn that math around and assume you have 96kW service and your stuff only runs 25% of the time, you could accommodate 384kW of load devices (running sporadically) in your house/shop. Of course it's a little more complicated than that. And that's why the load calc. sheet has different derating factors for different devices.
Do keep in mind your intended use of your shop. Is it a one man shop? You can't weld, use the plasma cutter, milling machine and air compressor simultaneously. Well, the plasma cutter and compressor do run together.... But this is a key part of the considerations. You have propane for heat today. That lowers electric demand. There is a push toward using heat pumps for everything.
All this begs careful thought to today and future usage. So it's great you are going through the exercise.
Great info, yes it's great exercise and so far I've learned a lot about the design and electrical requirements. I've also had to fill in a lot with unknowns and guestimates, since I have no info on the appliances we are getting installed other than the basics, plus adding in future growth (hot tub, shop, etc.) - it's all one large guestimate.
include "future" EV charging station(s) for load calc as justification for 320a
Good call. I'm not planning on going EV any time soon, but if they end up dominating the market and we buy one or two, then as some point we'll need some charging endpoints. I have 2x 240V in the garage planned for that.
You know why they are doing this right?
I had a similar issue when building my house, I told them what my future plans are and that I wanted an upsized (25kva) transformer so there would be no issue in the future. The complied.
Now as far as the 400amp service, unless you are planning on some insane equipment and operating all that equipment at the same time, 3 phase and such you don't need a 400amp service.
What you really are looking for is breaker space. Just get a 60 space 200amp panel and you will have what you want, if you need more space put a sub panel in. As far as the future detached garage is concerned, put a large 100amp or 200amp sub panel in the garage if you want off the main panel. You can also request a meter that has multiple lugs on it so you can run wire underground from the meter to the new detached garage.
Yes, I know exactly why they are doing this - mainly because it's required by them for any request over 200A...but I've talked with the engineer and am directly involved in the buildout since my builder is not handling it for me. Mainly going this way for a single meter on the house for simplified billing etc. for when we build the shop. And yes, we are planning on an upsized transformer so I'm with you there, as well accommodating for additional sub-panel(s) and breaker space for future growth. They way I see it, it's 200A for the house, 200A for the (future) shop.
What kind of equipment do you have in the shop? I have a 2500sqft house and a 1200sqft shop. I have a 240v compressor & a 240v plug for my welder. Also have a 4-post 120v lift and a Delta table saw. Various other things. All this runs off of one 200a service. Constant load at your house is probably 50a, I think you are over thinking this.
Welder (220V) and a QuickJack (120V), compressor (120V for now) and various points for charging tool batteries. Yes...I am overthinking it, that's one of my superpowers
If I can get ahead of the future growth items now and accommodate it during the new build, I'm hoping to have reduced cost and stress when it comes time to build the shop and add anything else to the 2 acre property.
84KW is an immense amount of power. I think your estimations are very high.
Large Appliances:
Dryer: 5kW (Large dryer, Max heat)
Range: 15kW (Premium dual-oven electric range with literally every burner and both ovens on)
Hot Tub: 6kW (Pump and heaters running at once)
Welder: 7.5kW (Miller Multimatic 220 @ Full Power)
That's 33.5kW, vs your estimated 40.8. And what are the odds you would be having all 4 of those machines going, at full power, simultaneously? It's a scenario that will basically never happen.
Small Appliances:
14.4 kW is a monumental amount of power for "small appliances". That's 8 high-powered hair dryers running at once, or 12 microwaves, or 18 coffee makers, or 40 refrigerators. I honestly don't think it's really possible for a residential home to hit 14.4kW in "small appliance" power consumption unless there were 6 kitchens and 30 people living there.
A more "realistic" "peak" small appliance load would be more like 5kW, IMO. Hair dryer, toaster, microwave, coffee maker, fridge/freezer, blender - somehow running all at once.
"House":
"3000sq/ft house x 4.8W = 14400W", where is this even coming from, and what does that even mean? Is that things like lights and random stuff people might have plugged in? 14.4kW is a ludicrous number for the random widgets and doodads someone might plug in. 14.4 kW is enough power for 72 PlayStation 5s, or about 140 70" televisions or 1,400 "75W Equivalent" LED light bulbs.
In a modern house with LEDs, I think you would be hard-pressed to exceed 500w total lighting load - even with an attached shop. Add a few TVs, computers, game console, maybe someone using a vacuum cleaner - and I think your peak "House" load would really be around 2kW
HVAC:
14400W for HVAC sounds very high since you said you have propane for heat. At most, I would expect a modern 5 ton AC system (typical 3,000 square foot home system) to consume about 5kW.
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So I'm calculating about 45.5kW or about 190A. If you get a gas range/oven, you're down to 127A. Add a gas dryer on top of that and now you're at 106A.
This is great info! Yes my estimations were very high, when I started this I pretty much had no clue but as I researched and read more I learned quickly that was way too high and to dialed it down. Even with what I submitted it's still high from a total consumption level but it's reasonable and it's now in the POCO hands to schedule and build out.
That looks a lot like the size of the breakers for those circuits. Not their factored power consumption.
You would be correct. I then dialed it back based on calculations after researching wattages per device/appliance.
It's all good for now, don't beat on me too bad - a couple of days ago I was lost, that's why I came here asking for some help, and now I have a little more knowledge and understanding than I used to, so thanks all that replied. I didn't expect the forum to be this active, but I'm glad it is!
If anyone wants to follow along with the house/garage build the thread is here:
https://www.garagejournal.com/forum...n-hill-country-700sq-ft.520505/#post-10274494
