Help with Multi-Family Calcs 220.40

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Sparky2791

Sparky2791

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Northeast, PA
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Electrical Design
Its been a long time since I did these and was wondering a few things as I refresh my memory.

When doing the calcs per 220.40(I know the longer harder way to do the calcs)

I know we have to provide 2 1500W small appliance circuit's and a 1500W Laundry circuit along with the 3kva per sq ft for lighting all which can apply to the demand factor.

How about the loads we figure for all the convenience receptacles at .18vA per receptacle in each apartment? Does that need to be included with the 2 small appliance , laundry and lighting load? Or assumed covered as part of the 2 small appliance circuits?

Individual fasted in place appliances (220.53) do Electric Water heaters apply to this?

I find 220.53 interesting

Is a microwave considered fastened in place if located above the range? Mine is fastened in place in my home.


I ask because if I have a dishwasher a microwave and an electric water heater (if this applies- see question above) I need to take the load at 100% of all 3. If I add a garbage disposal to the total I can use the 75% demand factor for all 4. Seems to me it would be to your benefit to add the 4th appliance in your calcs. What if that is an option to the tenant before they move in?

I am actually trying to get one of our Excel savvy engineers in our company to create a spreadsheet for 240.4.

Thanks for your replies
 
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LibertyEngineering said:
Its been a long time since I did these and was wondering a few things as I refresh my memory.

When doing the calcs per 240.4 (I know the longer harder way to do the calcs)

I know we have to provide 2 1500W small appliance circuit's and a 1500W Laundry circuit along with the 3kva per sq ft for lighting all which can apply to the demand factor.

How about the loads we figure for all the convenience receptacles at .18vA per receptacle in each apartment? Does that need to be included with the 2 small appliance , laundry and lighting load? Or assumed covered as part of the 2 small appliance circuits?

Individual fasted in place appliances (220.53) do Electric Water heaters apply to this?

I find 220.53 interesting

Is a microwave considered fastened in place if located above the range? Mine is fastened in place in my home.


I ask because if I have a dishwasher a microwave and an electric water heater (if this applies- see question above) I need to take the load at 100% of all 3. If I add a garbage disposal to the total I can use the 75% demand factor for all 4. Seems to me it would be to your benefit to add the 4th appliance in your calcs. What if that is an option to the tenant before they move in?

I am actually trying to get one of our Excel savvy engineers in our company to create a spreadsheet for 240.4.

Thanks for your replies
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Convenience receptacles are part of the 3va for dwelling units. BTW it is 180va per receptacle. Small appliance branch circuits are a minimum of two and includes all the receptacles they are required to feed.
 
You should definitely follow 220.82. It gives the most reasonable service sizes and it's easy to understand. The only time I even consider using a different method is when there are multiple ranges or dryers in the dwelling unit and that is quite rare.
 
JoeStillman said:
You should definitely follow 220.82. It gives the most reasonable service sizes and it's easy to understand. The only time I even consider using a different method is when there are multiple ranges or dryers in the dwelling unit and that is quite rare.
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Agree! In my case for this project it would also be 220.84
 
JoeStillman said:
You should definitely follow 220.82. It gives the most reasonable service sizes and it's easy to understand. The only time I even consider using a different method is when there are multiple ranges or dryers in the dwelling unit and that is quite rare.
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Thread title says multifamily - so chances are there is multiple of a lot of things when it comes to calculating main service/feeder. Maybe not so much multiples for feeder to individual units though.
 
kwired said:
Thread title says multifamily - so chances are there is multiple of a lot of things when it comes to calculating main service/feeder. Maybe not so much multiples for feeder to individual units though.
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The multi-family method of 220.84 bears little resemblance to the single-family method of 220.82. We do a 220.82 spreadsheet for each unit, then start over with a spreadsheet that does 220.84 for the whole building. It's a rare occasion indeed when a 220 Part III calculation comes up with a smaller service size than 220 Part IV (220.84). Even if there are gas ranges and you use the 8kW "simulated ranges" of 220.84, you'll come out ahead.
 
JoeStillman said:
he multi-family method of 220.84 bears little resemblance to the single-family method of 220.82. We do a 220.82 spreadsheet for each unit, then start over with a spreadsheet that does 220.84 for the whole building. It's a rare occasion indeed when a 220 Part III calculation comes up with a smaller service size than 220 Part IV (220.84). Even if there are gas ranges and you use the 8kW "simulated ranges" of 220.84, you'll come out ahead.
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Thanks JoeStillman - We basically do the same thing, our 220.84 calc is based on the outcome of 220.82 per unit. Commercial electrical design is so much easier, in my book. But the optional calcs make it much easier for resi calcs to be done.
 
You have many sections of the code and they are not correct. The title has 224.40 which doesn't exist, then you have 240.4 which is not about calcs. So we have all code sections that don't make sense. If you can't correct them I am happy to but give the correct sections

Do you want 220.84 in the title?
 
JoeStillman said:
The multi-family method of 220.84 bears little resemblance to the single-family method of 220.82. We do a 220.82 spreadsheet for each unit, then start over with a spreadsheet that does 220.84 for the whole building. It's a rare occasion indeed when a 220 Part III calculation comes up with a smaller service size than 220 Part IV (220.84). Even if there are gas ranges and you use the 8kW "simulated ranges" of 220.84, you'll come out ahead.
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Curious. Have you ever added the electric range into the calculations to allow the use of 220.84 instead of part III? Multi-family housing has exploded here in the Lehigh Valley over the last few years
 
Dennis Alwon said:
You have many sections of the code and they are not correct. The title has 224.40 which doesn't exist, then you have 240.4 which is not about calcs. So we have all code sections that don't make sense. If you can't correct them I am happy to but give the correct sections

Do you want 220.84 in the title?
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Sorry Dennis - Typed that after a 15 hour day of work. Should have been 220.40 in the title. Also 220.40 where I have 220.4 Obviously proof reading not my strongest point after working that long. Ill edit the OP but not sure how to edit the title. if you would please. Thanks and Merry Christmas
 
LibertyEngineering said:
Sorry Dennis - Typed that after a 15 hour day of work. Should have been 220.40 in the title. Also 220.40 where I have 220.4 Obviously proof reading not my strongest point after working that long. Ill edit the OP but not sure how to edit the title. if you would please. Thanks and Merry Christmas
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Having trouble editing the OP. Will not allow me too.
 
roger said:
There is a 10 minute edit window although there are times when the software may allow it. Dennis can fix it for you.
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I'd rather not change the OP at this time, or if one does you about have to change or delete replies or someone reading through the thread for the first time might get lost. Other solution would be to change OP but make notes within it to indicate what was changed so that anyone reading for first time knows what was going on.

I think that is a part of the reason for not allowing editing without moderator intervention after 10 minutes, things can get confusing if you change something after people have made replies to what was originally there.
 
kwired said:
I think that is a part of the reason for not allowing editing without moderator intervention after 10 minutes, things can get confusing if you change something after people have made replies to what was originally there.
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Bingo!
 
LibertyEngineering said:
Curious. Have you ever added the electric range into the calculations to allow the use of 220.84 instead of part III? Multi-family housing has exploded here in the Lehigh Valley over the last few years
Click to expand...
Yes, we use a spreadsheet that compares the two methods. You just have to enter the details of unit size and decisions about D/W, M/W, dryers, water heaters, ranges and HVAC. The spreadsheet tells you the minimum service size for Part II and Part IV methods. Part IV wins for buildings with more than 30 units or so, gas cooking or not.

We always attach the final (usually Part IV) spreadsheet to the drawing with the single line diagram. People were freaking out because the line item for ranges used to say "simulated ranges". "But it's gas cooking!" they'd say. I changed it to "cooking appliance allowance" and now it passes every time.
 
JoeStillman said:
Yes, we use a spreadsheet that compares the two methods. You just have to enter the details of unit size and decisions about D/W, M/W, dryers, water heaters, ranges and HVAC. The spreadsheet tells you the minimum service size for Part II and Part IV methods. Part IV wins for buildings with more than 30 units or so, gas cooking or not.

We always attach the final (usually Part IV) spreadsheet to the drawing with the single line diagram. People were freaking out because the line item for ranges used to say "simulated ranges". "But it's gas cooking!" they'd say. I changed it to "cooking appliance allowance" and now it passes every time.
Click to expand...
Thanks Joe.
 
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