Fun practice Service Load Calc.

[Konen]

I love these load calculation, and can't find anywhere online to practice them. So I figured I would post one and see what everyone else gets for their answers.

Multi-Family Standard Calculation

-6 units @750 ft²
Each unit has;
-2 small appliance
-1 laundry
-DW @ 1100va
-Water heater @ 3500va
-Garbage Disposal @ 850va
-Dryer @ 3.5kw
-Range @ 8kw
-Heat @ 3kw 240v
-A/C @ 17a 240v

Service Size?
Minimum THWN Copper Service Entrance?
Minimum THWN Copper Neutral?
120/240v, 3-wire, single-phase

 

[Dennis Alwon]

This sounds like a sneaky way to get us to answer it for you... hahaha. What did you get and we will compare.

 

[Konen]

This sounds like a sneaky way to get us to answer it for you... hahaha. What did you get and we will compare.

Oh not at all I have the book and answer key , it's out of the 2020 master electrician study guide.

 

[Dennis Alwon]

Is this correct

Total Demand 343 amps-- 400 amp service

 

[david luchini]

451A demand load.
500A service size.
2sets of #4/0 THWN Cu

 

[Dennis Alwon]

I was doing a 3 phase calc.... I see the 120/240 at the bottom of the op

 

[Dennis Alwon]

David what Va did you get. I got 123,630 VA

 

[xformer]

306 A - Hots
177 A - Neutral

 

[Konen]

451A demand load.
500A service size.
2sets of #4/0 THWN Cu

Perfect, what did you get on the Neutral?

 

[Konen]

306 A - Hots
177 A - Neutral

Negative, David nailed it though.

 

[Konen]

I was doing a 3 phase calc.... I see the 120/240 at the bottom of the op

I did that the first time too

 

[david luchini]

David what Va did you get. I got 123,630 VA

I got 108,270 VA

16,125VA for light, SA and Laundry
24,525VA for appliances
22,500VA for dryers
20,640VA for ranges
24,480VA for A/C

 

[david luchini]

Perfect, what did you get on the Neutral?

Didn't have time...and am not in front of the Code currently. Will have to take a look when I get a chance.

 

[Dennis Alwon]

I see where I went wrong... I used a calculator but some numbers were incorrect.... I should have check it better. The neutral is 153 amps I think

 

[Konen]

Neutral answer was not in the book, I added that in there so I could try to solve more than what was asked. You may be right but I got 258A for neutral. Wonder what David will get

 

[Dennis Alwon]

I have exactly what David had. Does the book break it down?

 

[Dennis Alwon]

This spreadsheet needs work-- my neutral is now 230 amps

 

[Konen]

I have exactly what David had. Does the book break it down?

He's right

I have exactly what David had. Does the book break it down?

He's right, I shouldn't have gone back and looked at the book I'll post picture of the one we are talking about now.

 

[Konen]

This spreadsheet needs work-- my neutral is now 230 amps

He's right

He's right, I shouldn't have gone back and looked at the book I'll post picture of the one we are talking about now.

I gotta get some sleep, I'll post tomorrow, I'm so tired I've posted the wrong information 3 times now and had to delete to many papers on my desk

 

[NAjxBUEEdA7PoKoX7vD2]

Did not include the neutral calc or the largest motor.

Feeder:
111.8 standard
73.8 optional
29280 VA

Service:
458 standard
322 optional
175680 VA

2 sets of 4 / 0 THWN Cu in separate conduits

For 3 phase:

Feeder:
125.0 standard
85.2 optional
29280 VA

Service:
339 standard
214.7 optional
175680 VA