Another

[Ohm1]

****This was taken from another site. Also, these questions are to let you see what others may be missing*******


Duplex 120v/240/ 1 Phase service each 1900 sq feet
9Kw range
5a dispo
11a DW
3Kw hot water
20Kw heater
3-21a 240v A/C

Answers=256/282/299/321


Here I messed up on the laundry. It doesn't mention laundry, so I added in the laundry, but not the dryer load! :(

This is what I done:
1900(3)=5700
1500(2)=3000
1500(1)=1500
=10200(2)=20400-3000@100%
=17400@.35=6090+3000=9090

Dispo=600
DW=1320
H20=3000
=4920(2)=9840(.75)=7380

Range=11,000
A/C Omit
Heat=20000(2)=40,000
Total=67470/240=281 (without dryer)

Now this is my question???If I add the dryer, I get=77470/240=322.7. Now I am off by one for the first, and off by one for the second answer???? What would be the correct answer (282/ 321).

[mdshunk]

My feeling is that you must add the 1500va laundry circuit for each unit. You do not arbitraily add a non specified dryer, because the dryer may be gas fired.

However, for real life purposes, I generally calculate in an electric dryer and an electric range, because plans can and do change in later years. Bigger homes I also add in a hot tub to the calculation if it seems like the type of house that might have one later on. If adding this non existant stuff makes the difference between one service size or another (say from 200 to 320), then I present the options to the customer or GC so that they can make an informed choice. Some of my southern sparkie buds have local rules requiring them to add in pool equipment to the calculation even if it doesn't exist.

[paul]

Here is what I got:
general lighting=
1900ft * 2 units * 3VA =..............4920 VA
laun and kit (4500VA * 2 units).....9000 VA
apply table 220.11 .................................................. .......9090 VA
appliances
dishwasher 5A * 120 V * 2 units..........1200 VA
garb dispos 11A * 120 V * 2 units..........2640 VA
water heater 3000VA * 2 units..........6000 VA
apply 220.17 (75% rule for 4 appliances) ...........................7380 VA
cooking eqpt
col C no notes apply use straight from col........................ 11000 VA
heat/cool
bigger is heater (20000 VA * 2 units)...............................40000 VA
Adding all the VA up:
total VA................................................ ......................67470 VA


total Amps (VA/240).............................................. ......281.1 Amps
Which is the same exact answer you got, so there is 2 votes for 282 Amps!

[Ohm1]

Thanks Paul!