Using the standard method calculate the load in amps on a Duplex,,each unit has;;1900 square feet,,one 7000va range,,,,,one 1200va disposal,,,,one 1320va Dishwasher,,,one 3000va Hwt heater,,,,one 20000va central heat,,, five 21amp//240volt AC units.Can someone please help to figure this question out???
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
two family dwelling load calculation
- Thread starter brookside
- Start date
- Status
- Not open for further replies.
bphgravity
Senior Member
- Location
- Florida
Re: two family dwelling load calculation
1. Take the square footage of the living areas and multiply it by 3 VA.
2. Small Appliance = 4 x 1500 VA, Laundry = 2 x 1500 VA.
3. Apply allowable lighting demand to the above steps.
4. Compare heat to A/C. Omit the smaller.
5. A 75% demand can be provided for 4 or more fixed appliances.
6. Dryers at 5 KW minimum. (neutral at 70%)
7. Demand for cooking equipment per Table 220.19. (neutral at 70%)
8. Largest motor is to be increased by 25%.
9. Size the service by dividing the total VA by the connected voltage and apply Table 310.15(B)(6). Use Table 250.66 to size the GEC.
Go ahead and post the numbers you get and then we can go over where you might be going wrong or with what you are having problems with.
1. Take the square footage of the living areas and multiply it by 3 VA.
2. Small Appliance = 4 x 1500 VA, Laundry = 2 x 1500 VA.
3. Apply allowable lighting demand to the above steps.
4. Compare heat to A/C. Omit the smaller.
5. A 75% demand can be provided for 4 or more fixed appliances.
6. Dryers at 5 KW minimum. (neutral at 70%)
7. Demand for cooking equipment per Table 220.19. (neutral at 70%)
8. Largest motor is to be increased by 25%.
9. Size the service by dividing the total VA by the connected voltage and apply Table 310.15(B)(6). Use Table 250.66 to size the GEC.
Go ahead and post the numbers you get and then we can go over where you might be going wrong or with what you are having problems with.
Re: two family dwelling load calculation
Bryan thank you for responding to that I Actually sat down and reasoned things out in my head and came up with the same formula,, I have another one for you if you get a multiple A/C load,,say five 18 amp/120volt Air Conditioners,and say 20000va Central heat,,would you add all the ACunits together then stand them up to the central heatand omit the smaller ,,or would you just add one of the AC units,,I lean to adding up all of them but I thought I might ask someone
Bryan thank you for responding to that I Actually sat down and reasoned things out in my head and came up with the same formula,, I have another one for you if you get a multiple A/C load,,say five 18 amp/120volt Air Conditioners,and say 20000va Central heat,,would you add all the ACunits together then stand them up to the central heatand omit the smaller ,,or would you just add one of the AC units,,I lean to adding up all of them but I thought I might ask someone
Re: two family dwelling load calculation
Hello brookside, I am getting ready to take the 01 (in WA)test on the 25th of this month.
From your post at http://www.mikeholt.com/codeforum/ultimatebb.php?ubb=get_topic;f=6;t=000209, you stated that they ask the same question but in two different versions, what other types of calc's do they ask.
Any thing that can help me repair would be great from ANY one that has taken the test in WA.
---brookside I also sent ya a private msg---
Hello brookside, I am getting ready to take the 01 (in WA)test on the 25th of this month.
From your post at http://www.mikeholt.com/codeforum/ultimatebb.php?ubb=get_topic;f=6;t=000209, you stated that they ask the same question but in two different versions, what other types of calc's do they ask.
Any thing that can help me repair would be great from ANY one that has taken the test in WA.
---brookside I also sent ya a private msg---
rod
Member
- Location
- North Carolina
Re: two family dwelling load calculation
Brook,
Take a look at the thread of posts titled "need advice for residential load calc" by msext. I think it's one below yours. We worked a lot on this one; although his example is a tad bit different than yours. If you look at the a/c load being 21 amps you know it's probably not cord & plug connected so they must be fastened in place. So you'd be right to add them together and consider them one load and yes you can apply the 70% demand factor. As in Mike's question the author of the question probably was considering those split units as his non-centralized a/c. Also, look closely at article 220.33. Since the demand factor table (220.32) for multi-family dwellings starts at three units, art 220.33 provides for two family units. Check it out! You also mentioned what if you had 5 - 18 amp, 120V a/c units. You know that you don't want to load up branch circuits above 80%. IF you had 20 amp a/c branch circuits, 80% is still just 16 amps so you exceed that limit. Given an 18 amp load you'd probably have to consider that a fastened in place appliance and go at it the same way as the other example; of course that's standard calculation. As you know it will be handled a little differently in the optional calculation. One thing that I'm not too sure about, unless it's a local code thing for you guys out there is why did bphgravity include 4 small appliance circuits and 2 laundry circuits. In all the residential calcs I've ever done it calls for the minimum 2 small appliance circuits and 1 laundry circuit. I'd be interested to learn about this piece. Good luck.
Rod
Brook,
Take a look at the thread of posts titled "need advice for residential load calc" by msext. I think it's one below yours. We worked a lot on this one; although his example is a tad bit different than yours. If you look at the a/c load being 21 amps you know it's probably not cord & plug connected so they must be fastened in place. So you'd be right to add them together and consider them one load and yes you can apply the 70% demand factor. As in Mike's question the author of the question probably was considering those split units as his non-centralized a/c. Also, look closely at article 220.33. Since the demand factor table (220.32) for multi-family dwellings starts at three units, art 220.33 provides for two family units. Check it out! You also mentioned what if you had 5 - 18 amp, 120V a/c units. You know that you don't want to load up branch circuits above 80%. IF you had 20 amp a/c branch circuits, 80% is still just 16 amps so you exceed that limit. Given an 18 amp load you'd probably have to consider that a fastened in place appliance and go at it the same way as the other example; of course that's standard calculation. As you know it will be handled a little differently in the optional calculation. One thing that I'm not too sure about, unless it's a local code thing for you guys out there is why did bphgravity include 4 small appliance circuits and 2 laundry circuits. In all the residential calcs I've ever done it calls for the minimum 2 small appliance circuits and 1 laundry circuit. I'd be interested to learn about this piece. Good luck.
Rod
- Status
- Not open for further replies.