not homework but confusing myself

[Adamjamma]

Ok, I have been trying to do an interesting to me calculation of a home with a granny apartment in it. It is based upon four floors including the basement. But, I have been getting myself confused when trying to compare with or without the apartment, so, someone correct me or show me the correct codes at least: Here it is..lol...

Apartment:
19 feet by 50 feet 3va 2850 Va
3 small appliance circuits 4500
stove 8000
no washer
no dryer
no heating or cooling
No other appliances
total usage: 15350
first 8000
15350 – 8000 = 7350 * 0.40 = 2940
/240 45.6 50 amps
no stove__ 7350 amps/240v 30.6 amps






Whole house calc with apartment:
4 floors including basement and apartment
33 by 50 times 4 floors times 3Va = 19800
11 small appliance circuits over three floors 16500
garbage disposal 1176
2 ranges 16000
2 laundry 3000
0 dryers 0
2 dishwashers 2400
3 waterpumps 3528
total usage 62404
first 8000
62404-8000=54404 *0.40 = 21761 =29761
= 124 amps
if take out both stoves: 46404 so 23361 = 97.35 amps.


If I take out the circuits for the apartment… I get


47054 Va = 23621 = 98.42 amps. Or 85 amps without stove...


So somehow I get less amps with apartment than without apartment. What am I doing wrong?


Apartment is one range probably gas but...set for 8000 electric just in case
3 small appliance circuits
no washer or dryer
no extras.


Am I messing up somewhere???

 

[david luchini]

Ok, I have been trying to do an interesting to me calculation of a home with a granny apartment in it. It is based upon four floors including the basement. But, I have been getting myself confused when trying to compare with or without the apartment, so, someone correct me or show me the correct codes at least: Here it is..lol...

I've read it 5 times...you're confusing me too.

I can't figure out what you are trying to do or what Code sections you are applying.

 

[Adamjamma]

Well, the guy who sent it to me is trying to draw up plans on a house for a person that wants a granny apartment in the basement for the caretaker... they want to know if they actually need a separate meter or not... as they usually live out of country and thus are only there a few months every year, so would need to pay utilities anyway on the place... would pay the caretaker part of wages as utilities possibly..lol.

So, i have four floors as designed so far, a few coffee or kitchenette type areas on different floors, including the party deck, and a probable setup of two stoves, one in the apartment and one in the main kitchen, both probably gas...
no AC only ceiling fans which I believe is covered in standard lighting calc of 3Va per sqr foot...

so I calculated the building as four complete floors, combined, with all the various additions of the water pumps, the one garbage disposal, the two dishwashers the person apparently wants, etc... and that is where I started...

The apartment was designed again with the two appliance circuits and the one appliance circuit in the dining room area... but there will be no washer or dryer in the apartment...
Since the country does not use dryers at all, no dryers needed...
but the owner wanted two washer areas.. one in the garage for the caretaker to use and one locked up in main house for owner and his family...

So, I could not think of any other circuits I need to consider, customer did not send any, and my buddy did ot tell me of any others needed... so..think I covered everything... Since it is in the Caribbean there is no heat, and due to location in mountains area no normal need for AC as fans should cover it...
Luckily, it is only a way of practising for me, as the builder has his own electrician that will deal with the actual calcs etc...for the government..lol...

 

[kingpb]

Unless it is required to have utility grade metering for billing, why not just submeter the "caretaker apt" and subtract from total. A lot easier.

 

[Adamjamma]

apparently the customer is looking at the situation and wanted pricing for separate compared to part of the overall home...
if separate, obviously would need own panel and wiring...

Since it is Jamaica, all decisions need done before the foundation gets poured as all conduits, water pipes, drains, etc, must be done as part of pre planning... or they cost six times as much to fix... so I am giving my own take, the contractors electrician his take, and the ultimate decision is the customer... what they want...
But, this is for a freind who is still a young architect... and so far between myself and the customer, has had to make a few changes before his submission to the board for permits...

I just wish he would quit making such pretty drawings without learning the basics of plumbing and such... I keep having to tell him his drains and vents will not work and then he has to redraw and talk with the customer... lol... The trials of trying to help out a guy who thinks his college degree taught him everything he needs to know...

Anyway, since I am stuck trying to figure this out... am just trying to see if I applied everything correctly... before starting to work out the figures for him to give as an idea of costings... It is tough when I am currently in UK, the architect and main builder is in Jamaica, and the customer is in Canada, but her sister lives near me to consult with me... lol.. the sister actually got me involved because she remembered I had worked with the architect a few times before...
So, hopefully, will get a few pounds out of the whole deal..lol... if not, at least it gives me some more stuff to work out math on, trying to get my designing stuff correct for tests...

 

[al hildenbrand]

So somehow I get less amps with apartment than without apartment. What am I doing wrong?

Intuitively, it seems that you are accounting for the NEC specified line items (prior to summing) accurately.

The lump sum that is allowed the 40% reduction is where your final Amperage number "squirm" is coming from.

 

[david luchini]

Am I messing up somewhere???

What Code sections are you trying to use for your load calculations? What you have posted doesn't seem to match any section.

 

[Chamuit]

I get combined - 124A

Separated
- Main 105A
- Servants 48A

 

[Adamjamma]

Intuitively, it seems that you are accounting for the NEC specified line items (prior to summing) accurately.

The lump sum that is allowed the 40% reduction is where your final Amperage number "squirm" is coming from.

ok.. so... the optional says to use 8000 as standard.. then use 40 percent of the rest... if less than 8000 then use at 100 percent...
I dont see ways to use the two stoves as offset because they are in different kitchens so if used, they both should be counted yet, 90 percent of the stoves used there, due to cost of electricity, are gas..lpg... so am trying to use with and without...

I guess my 40 percent is where I am having the problems along the lines... that and the changes from if both apartment and house are single unit, and if they are two services...

I know that the idea of a major home having only 200 watts is sounding kind of low but average temp in the area that the house is going is 78 degrees, year round, which the customer knows, having grown up there, and feels no AC needed... just fans and proper wall design...
Also, with only 18 days of rain on average in his area, there should be no dryer needed for clothes, and he has a covered porch to use if necessary as well... I am jealous because plans have a porch of 30 feet by 12 feet, lol... overlooking a valley...

Even with a stove in the apartment, the load calcs have it at around 70 amps max and when I did a solar estimate using lighting positions as the architect drew them so far, etc, the apartment can be run on an 8000 watt inverter easily... at least that is what the software shows...

yet still I worry about the calculations... but we dont have many of the things in Jamaica that are popular in the USA...

 

[Adamjamma]

I get combined - 124A

Separated
- Main 105A
- Servants 48A

ok, so my calc complete at 124 is ok... my servants at 46 and yours at 48 seems close enough... both hit the fifty mark easy enough...

guess I was just wondering how I got combined of 125 roughly yet when I combine the two I got around 160... that was what was throwing me... but guess I am close on what I am doing with the figures... just need to keep doing these types of calculations until I can do them without feeling something is wrong on them or those tests may kick my butt...
Learned when doing the Book Keeping tests that repetition is what I need to get the figures right...

 

[Adamjamma]

Intuitively, it seems that you are accounting for the NEC specified line items (prior to summing) accurately.

The lump sum that is allowed the 40% reduction is where your final Amperage number "squirm" is coming from.

ok, thanks... think if I had set it up line by line instead of grouping it in my math shorthand it might have been clearer to see where my errors may be..lol...
It would help if I had exact nameplate numbers on the various things but all i have is a wishlist... as home would not be ready for appliances for 18 months under projections... so kind of need to fudge but at least on some things, like the water pumps, I can use the ones I have installed as a basis to start, since this house and my own house are only off in a few areas... so some things like water pumps and tanks should be the same... plus there are only so many water pumps available retail on the island, unlike the USA... I think currently there are three sizes by five companies available..any others need brought in...
same with stoves... about six electric stoves..three brands... available via retail..but over fifty styles of gas stoves...

 

[david luchini]

ok.. so... the optional says to use 8000 as standard.. then use 40 percent of the rest... if less than 8000 then use at 100 percent...
..

The optional method says the 1st 10,000 VA at 100%.

It also says to use the nameplate rating of the range, not the 8kw used in the standard calculation.

It also says it is for a single dwelling unit, so you can't use the optional method for the two units combined.

 

[Adamjamma]

Ok, thanks. So I messed up by using my stuff that for some reason has 8000 as the 100% instead of 10000...
also, cannot use a nameplate when no nameplates will be bought for at least 18 months, and probably will be just a propane stove... but if electric I have three possible... in local stores there so far, sizes to choose from and chose the biggest one...lol...
anyway... gotta change my notes then... wonder where I got 8000?? 2011?

 

[david luchini]

wonder where I got 8000?? 2011?

Its been 10,000 as long as I can remember.